Please look below for detailed schedule.
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Abstract Number: ANPA2023-N00057 Presenting Author: Chetan Dhital (Invited) Presenter's Affiliation: Department of Physics, Kennesaw State University Location: Virtual Presentation Show/Hide Abstract The simultaneous breaking of space inversion and the time reversal symmetries in_x000D_
solids lead to several novel electronic and magnetic phases such as magnetic Weyl_x000D_
semimetals, Dirac semimetals, Fermi arcs, and magnetic skyrmions. Furthermore, it_x000D_
leads to the possibility of tuning electronic topological phases with magnetism and_x000D_
vice versa. Materials having heavy rare earth elements are suitable for the study of_x000D_
intertwined electronic band topology and magnetism due to their penchant for longrange magnetic ordering, strong spin-orbit coupling, and low carrier density semimetallic behavior. Recent studies have indicated that RAlGe (R=Rare earth) family_x000D_
of materials have shown promising electronic and magnetic behavior indicating the_x000D_
connection between electronic topology and magnetism. Recently our group has_x000D_
studied the electrical and magnetic behavior of NdAlGe. Our observations indicate_x000D_
that NdAlGe has complex magnetic structure indicated by two magnetic_x000D_
wavevectors, low carrier density semi metallic behavior, and two regions of large_x000D_
anomalous Hall effect. The electronic structure calculation indicates the presence of_x000D_
Weyl nodes near Fermi surface and nested Fermi pockets with nesting vector equal_x000D_
to the magnetic wavevector. The observed anomalous Hall conductivity is close to_x000D_
the calculated intrinsic conductivity from Berry curvature. I will discuss these results_x000D_
in reference to the interplay between electronic topology and magnetism._x000D_
This work is supported by NSF DMR-2213443.
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Abstract Number: ANPA2023-N00063 Presenting Author: Nepal Rama Devi Presenter's Affiliation: Ph.D. scholar Title: Dysprosium doped Y3Ga4AlO12 and Lu3Ga4AlO12 nano-garnets for white light emitting diodes Location: Virtual Presentation Show/Hide Abstract Trivalent dysprosium (Dy3+)-doped Y3Ga4AlO12 (YGAG) and Lu3Ga4AlO12 (LuGAG)
nanocrystalline garnets have been synthesized by Pechini Sol-Gel method. These garnets were characterized by X-ray diffraction (XRD) method, scanning electron microscopy, Fourier
Transform infrared spectroscopy and photoluminescence spectroscopy to determine structure, phase, morphology, vibrational modes and luminescence properties. From XRD results, it is noticed that these garnets are single phase with crystallite sizes of 16 and 19 nm for YGAG and LuGAG, respectively. Morphology results showed that, the particles are nearly spherical and agglomerated with an average grain size of 50-70 nm. From the excitation spectra, it is observed that these phosphors can be effectively excited by near ultraviolet and blue LEDs.
Under the excitation of ultraviolet light at 360 nm, the photoluminescence spectra of both the samples consist of characteristic emission peaks at 489 nm (blue) and 579 nm (yellow)
corresponding to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+, respectively. By
substituting the Y3+ ions with Lu3+ ions, the luminescence intensity of Dy3+-doped LuGAG is slightly enhanced due to crystal-field effect around the Dy3+ ion. The CIE chromaticity co-ordinates of both the phosphors were located in the white light region. The results indicated
that, both the phosphors can be utilized for the white light generation under 360 nm excitation.
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Abstract Number: ANPA2023-N00061 Presenting Author: Suresh Gnawali Presenter's Affiliation: Georgia State University Title: Optical Nonlinearities in Graphene Quantum Dots: High Harmonic Generation Location: Virtual Presentation Show/Hide Abstract Graphene quantum dots (GQDs), the graphene nanoparticles of a few nanometers excited by an ultrafast optical pulse of a few femtoseconds, exhibit several optical nonlinearities, including residual population and high harmonic generation (HHG). By introducing dephasing, we addressed nonlinearity, namely HHG in GQDs placed in a short linearly polarized optical pulse. At short finite dephasing times, the ultrafast electron dynamics show significant irreversibility with a large residual population of the excited quantum dot levels. When dephasing time increases, intensities correspond to a low-frequency boost, while the cutoff energy decreases regarding the high harmonic spectra. The cutoff energy's dependence on the optical pulse's amplitude is also sensitive to the frequency of the pulse. This dependence is almost linear when the optical pulse frequency is much less than the quantum dot band gap. However, when the pulse frequency is comparable to the band gap, the cutoff energy shows saturation behavior at a large field amplitude, >0.4 V/Ã…. In triangular graphene quantum dots with zigzag edges, the intensities of high harmonics show a strong dependence on the initial electron population of the edge states of the quantum dot. If a zigzag triangular quantum dot possesses an even number of edge states, then, even high harmonics are strongly suppressed when half of the edge states of the quantum dots are populated before the pulse. For any other populations of the edge states, the odd and even harmonics are of comparable intensities.
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Abstract Number: ANPA2023-N00074 Presenting Author: Sunny Choudhary Presenter's Affiliation: University of Puerto Rico, San Juan, PR, USA, 00936 Title: The Doping Effect of Aluminium on Nickel Site in Nano Structured Nickel Ferrite Location: Virtual Presentation Show/Hide Abstract Nanocrystalline aluminium doped nickel ferrite [Ni1-xAlxFe2O4 (x= 0, 1/2)] powders have been synthesized by using sol-gel method and the effect of aluminium content on the structural and dielectric properties has been studied. The X-ray diffraction (XRD) revealed that the powders obtained single phase with spinel structure. The lattice constant, interplanar distance and crystallite size decrease with increasing the doping of Al content. In the Raman analysis, there are five active bands present in the pure and aluminium doped nickel ferrite. Raman peaks over the region of 620-720 cm-1 represent the modes of tetrahedral group (T-site) and 450-620 cm-1 region corresponds to the modes of octahedral group (O-site) of ferrites. Dielectric behaviour of sample showed that the value of dielectric constant (ε′) and dielectric loss decreases with frequency and confirmed the general behavior of ferrites. The AC Conductivity (σac) decreased as the Al content increased in the samples. The phenomena explained on the basis that Al ions occupy the tetrahedral sites in the Ni ferrite, depleting the Ni3+ ion number present at the tetrahedral site.
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Abstract Number: ANPA2023-N00064 Presenting Author: Prakash Khatri Presenter's Affiliation: PhD Scholar, Tribuvan University Location: Virtual Presentation Show/Hide Abstract Half-Heusler compounds show promise as high-temperature thermoelectric materials, offering a potential solution to the energy crisis. This study extensively examines the structural, electronic, lattice dynamics, mechanical, and thermoelectric properties of 18 valence electron TiXPb (X=Ni, Pd, Pt) compounds by using density functional theory (DFT), semi-classical Boltzmann transport theory (BTE), and deformation potential theory (DPT). The compounds are thermodynamically and mechanically stable, exhibiting ductility. TiNiPb, TiPdPb, and TiPtPb are identified as semiconductors with indirect band gaps of 0.33 eV, 0.35 eV, and 0.72 eV, respectively. By utilizing the semi-classical BTE, we assess the various transport parameters with respect to the chemical potential. P-type doping of these materials leads to a high power factor comparable to certain other half-Heusler materials. At room temperature, TiNiPb, TiPdPb, and TiPtPb have lattice thermal conductivities of 41.03 Wm-1K-1, 15.56 Wm-1K-1, and 23.17 Wm-1K-1, respectively, while demonstrating maximum ZT values of 0.09, 0.27, and 0.54 for p-type elements. In conclusion, our investigation highlights TiPtPb as a promising candidate for high-temperature power generation among the compounds studied.
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Abstract Number: ANPA2023-N00054 Presenting Author: Da'Shawn M. Morris Presenter's Affiliation: Department of Chemistry, Physics and Materials Science, Fayetteville State University, Fayetteville, North Carolina 28301, United States Title: Energy dispersion of self-assembled single walled carbon nanotube arrays Location: Virtual Presentation Show/Hide Abstract Carbon nanotubes (CNTs) are cylindrical carbon structures with diameters of as low as a few nanometers. A CNT can be perceived as a rolled-up graphene sheet of one-atom-thick layer of carbon atoms arranged in a hexagonal lattice. CNTs are known for their exceptional mechanical, optical, and electrical properties, which make them ideal for a wide range of opto-electronic applications. We theoretically investigate the dynamical conductivity and dielectric responses of single-walled CNTs (SWCNTs) of different chirality using the k.p method of the band structure theory in addition to the low-energy plasmonic response calculation technique and the many-particle Greens function formalism. We model a thin film of SWCNTs as periodically aligned cylinders of the same length, radius and chirality immersed in a dielectric medium of constant permittivity. We find that the conductivities and the dielectric responses of a SWCNT are chirality dependent. We also investigate the energy dispersion of SWCNT films and estimate their excitonic energy gaps. For a film of homogeneous periodically aligned (11,0) SWCNT, the excitonic energy gap is about 2.32 eV.
This work is supported by the National Science Foundation RIA 1900998.
References:
1. C. M. Adhikari, I. V. Bondarev, J. Appl. Phys. 129, 015301 (2021).
2. I. V. Bondarev, C. M. Adhikari Phys. Rev. Applied 15, 034001 (2021).
3. G. D. Mahan, Many particle physics (Kluwer Academic, New York, 2000), 3rd ed.
Correspondence: cadhikari@uncfsu.edu
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Abstract Number: ANPA2023-N00058 Presenting Author: Parashu Kharel Presenter's Affiliation: Department of Physics, South Dakota State University Location: Virtual Presentation Show/Hide Abstract Magnetic materials exhibiting high spin polarization at the Fermi level have applications in spin-transport-based devices. Heusler alloys showing this behavior have attracted much attention because of their tunable magnetic and electronic properties, and high Curie temperature much above room temperature. We have carried out combined experimental and theoretical investigations of two such materials CoFeVAl and CoFeV0.5Mn0.5Al. The first-principle calculations indicates that both CoFeVAl and CoFeV0.5Mn0.5Al are ferromagnetic with high spin polarization of 87% and 96%, respectively. We have synthesized bulk ingots of both samples in cubic crystal structure with some structural disorder. The magnetic properties of CoFeV0.5Mn0.5Al are consistent with the theoretical prediction but that of the parent compound are slightly different. These results indicate that CoFeV0.5Mn0.5Al with nearly half-metallic band structure and high Curie temperature above room temperature has potential for spintronic applications.
This research is supported by the National Science Foundation (NSF) under Grant Numbers 2003828 and 2003856 via DMR and EPSCoR.
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Abstract Number: ANPA2023-N00068 Presenting Author: Anup Pradhan Sakhya Presenter's Affiliation: University of Central Florida Title: OBSERVATION OF FLAT BANDS AND DIRAC CONES IN A WEAKLY CORRELATED SEMIMETAL YRu2Si2 Location: Virtual Presentation Show/Hide Abstract Topologically non-trivial materials, especially topological semimetals and metals have emerged as new frontiers in the study of quantum materials, propelled by the discovery of topological insulators. Herein, a high-quality YRu2Si2 single crystal was studied by employing angle-resolved photoemission spectroscopy supported by first-principles calculations along various high-symmetry directions. We present the experimental observation of flat bands along the X-N-X and N-G-N high-symmetry directions within the binding energy range of 200 meV which is very near to the Fermi level. These flat bands originate from Ru d orbitals and were found to be sensitive to the polarization of light. In addition, ARPES data revealed Dirac cones at the G and the X points. The observed ARPES data is in excellent agreement with the density functional theory results. The presence of both flat bands and Dirac fermions in YRu2Si2 suggests a unique synergy of correlation and topology in this material belonging to the centrosymmetric tetragonal ThCr2Si2-type structure thus establishing for the first time a new platform to investigate the flat band physics in combination with non-trivial topological states in a weakly correlated system.
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Abstract Number: ANPA2023-N00060 Presenting Author: Resham Babu Regmi Presenter's Affiliation: George Mason University Title: Magnetotransport and electronic properties of altermagnetic MnTe Location: Virtual Presentation Show/Hide Abstract In addition to the well-known ferrro(ferri)magnets (FM) and Neel antiferromagnets (AF), a new class of magnetic materials has been recently realized. They are dubbed "altermagnets" (AM), since they are (a) principally different from the two "canonical" classes, and (b) as opposed to AF, they include alternating (staggered) magnetization density not only in the real space but also in the reciprocal space. MnTe is one of the handful of materials predicted to be altermagnetic. MnTe crystalizes in NiAs- type structure in space group P6/mmm. It orders into an antiferromagnetic state at a relatively high temperature of around 310 K. the magnetic structure consists of ferromagnetic Mn planes coupled antiferromagnetically along the c-axis such that two antiferromagnetic Mn sublattices are related not by a regular 6-fold rotation, but by a 6-fold screw axis thus providing the necessary crystal symmetry that couples with the spin structure to give rise to altermagnetism. Here we will present the magneto transport and electronic properties measured on the bulk single crystal of MnTe.
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Abstract Number: ANPA2023-N00059 Presenting Author: Hari Bhandari Presenter's Affiliation: George Mason University Title: Interplay between magnetism and electronic structure in the twisted-Kagome magnet HoAgGe Location: Virtual Presentation Show/Hide Abstract Kagome lattice magnets are an interesting class of materials that inherently allow a unique platform for the interplay between magnetism and electronic topology as they are one of the highly frustrated magnetic systems and also allow the simultaneous existence of topological flat bands and Dirac points. A kagome lattice consists of corner sharing equilateral triangles arranged forming a hexagonal pattern. In the RAgGe (R = rare earth element) compounds crystallizing in the ZrNiAl-type structure, the R atoms form the equilateral triangles similar to that in the kagome lattice, but these triangles are slightly rotated not making the prefect hexagonal ordering. Such a quasi-kagome lattice of the 4f electrons provides a platform for interesting physics, which was recently demonstrated by the discovery of the elusive spin-ice in HoAgGe. The spin-ice rules in this compound (one-in-two-out or two-in-one-out) are obeyed with increasing applied field along the b-axis, which leads to metamagnetic transitions in Ms/3 increments ( where Ms is the saturated magnetization). Here, we present the magnetotransport properties in the different magnetic states stabilized the magnetic field in this material. We have found a significant effect of the magnetic structure on the Hall conductivity. We will discuss the Hall conductivity as a function of magnetic field and temperature providing the evidence of the interplay between the intriguing magnetism and the electronic structure in this compound.
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Abstract Number: ANPA2023-N00067 Presenting Author: Alexis Jadiel Agosto Presenter's Affiliation: University of Central Florida Title: Observation of flat bands in niobium halide semiconductor Location: Virtual Presentation Show/Hide Abstract Observation of flat bands in niobium halide semiconductor
Alexis J. Agosto-Cuevas ,1 Sabin Regmi,1 Tharindu Fernando,2 Yuzhou Zhao,2 Anup Pradhan Sakhya,1 Gyanendra Dhakal,1
Iftakhar Bin Elius,1 Hector Vazquez,1 Jonathan D Denlinger,3
Jihui Yang,4 Jiun-Haw Chu,2 Xiaodong Xu,2 Ting Cao,4 and Madhab Neupane 1 ∗
1Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
2Department of Physics, University of Washington, Seattle, Washington 98195, USA
3Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
4Department of Materials Science and Engineering,
University of Washington, Seattle, WA 98195, USA
Alexis.Agosto@ucf.edu
Kagome materials are potential systems for Dirac fermions and flat bands, which make them suitable grounds for the study of topology and electronic correlations in geometrically frustrated quantum materials. This study investigates the electronic structure of one such material, Nb3I8, with a breathing kagome lattice of niobium atoms. We reveal the presence of multiple flat and weak dispersing bands, that are well captured in theoretical band calculations as well. Being a layered van der Waals material with a magnetic monolayer, this system will open up avenues toward the study of electronic correlations, magnetic order, and their interplay in two dimensions as well as toward its potential applications.
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Abstract Number: ANPA2023-N00065 Presenting Author: Dipendra Kumar Sah Presenter's Affiliation: Tribhuvan University Location: Virtual Presentation Show/Hide Abstract
Abstract
Thermodynamic properties, including the integral excess Gibbs free energy of mixing and the activity of components of Ni-Cr-Al-Ti quaternary liquid alloy at a composition and a temperature, were estimated by the General Solution Model (GSM) using thermodynamic databases of constituent binary subsystems. The linear temperature-dependent interaction energy parameters were used in the Redlich-Kister polynomial in order to compute the thermodynamic properties of binary subsystems. The surface concentration of components and surface tension of the quaternary liquid alloy were estimated using the Butler equation at different compositions and temperatures from Ni, Cr, Al and Ti corners. The integral excess Gibbs free energy of mixing of the quaternary alloy at all compositions was found to be negative and the negative value of the integral excess Gibbs free energy of mixing was found to decrease with the increase in temperature. The activity of the components Ni, Al and Ti was found to increase while that of Cr decreased with the increase in temperature of the alloys. The surface concentration of Al was higher and that of Ni, Cr and Ti was lower than their respective bulk concentrations in the alloys. The surface tension of the alloys decreased linearly with the increase in temperature at all compositions.
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Abstract Number: ANPA2023-N00072 Presenting Author: Sabin Regmi Presenter's Affiliation: University of Central Florida; Current Affiliation: Idaho National Laboratory Location: Virtual Presentation Show/Hide Abstract Niobium halides Nb3X8 (X = Cl, Br, I), predicted two-dimensional magnets, are recently being studied for the electronic properties coming from the structural breathing kagome geometry. In this work, we have studied niobium bromide by utilizing angle-resolved photoemission spectroscopy, supporting first-principles calculations, and Raman spectroscopy measurements. Experimental results reveal that multiple flat and weakly dispersing bands are present in its electronic structure. The theoretical calculations well reproduce the experimental results and show that these bands have niobium d character, indicative of their origination from niobium breathing kagome plane. Time-dependent Raman measurements show that this material is stable down to ultrathin limit, establishing its promise in heterostructure fabrication and applications. Our results also bring out Nb3Br8 as a platform for the study of interplay among structural geometry, magnetism, electronic correlations in three- as well as two-dimensions.
**This work is supported by the National Science Foundation (NSF) Career Grant DMR-1847962, the NSF Partnerships for Research and Education in Materials (PREM) grant DMR-2121953, and the Air Force Office of Scientific Research MURI Grant FA9550-20-1-0322.
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Abstract Number: ANPA2023-N00071 Presenting Author: Nathan Valadez Presenter's Affiliation: University of Central Florida Title: Gapless nodal lines in a rare-earth-based semimetal Location: Virtual Presentation Show/Hide Abstract Rare-earth-based semimetals in the ZrSiS family bring into play the potential correlation effects and magnetic ordering from the rare-earth 4f electrons in addition to the topological fermions that this family can support. Here, we investigate the electronic structure of a rare-earth-based ZrSiS-type system using the angle-resolved photoemission spectroscopy technique corroborated by density-functional theory calculations. The experimental results show the presence of multiple gapless Dirac nodes associated with multiple Dirac nodal lines in this system and these observations are well supported by calculated band structures. This work presents an insight into the topology in a rare-earth-based semimetal, which could be important to investigate its interplay with magnetic ordering, correlation effects, and spin-orbit coupling within such ZrSiS-type systems.
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Abstract Number: ANPA2023-N00066 Presenting Author: Shambhu Bhandari Sharma Presenter's Affiliation: University College London Title: Upgraded stability and machinability in penta-BCN by Fluorination Location: Virtual Presentation Show/Hide Abstract The first ternary pentagonal monolayer, penta-BCN, is theoretically predicted to be demonstrating extraordinary applicabilities in mechanical, optoelectronic, and energy storage devices. Nevertheless, there is still an open question of whether or not it remains stable in the pristine state.
Using the state-of-the-art first principle density functional theory calculation we demonstrate that the fluorination in penta-BCN not only makes it chemically stable but also fixes the dynamical instability by reducing the mechanical hardness. We trust, these enhancements are critcally important for the experimental synthesis and deployment of penta-BCN.
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Abstract Number: ANPA2023-N00070 Presenting Author: Milo Sprague Presenter's Affiliation: University of Central Florida Title: Observation of Spin-Degeneracy Lifting in Paramagnetic EuZn2Sb2 Location: Virtual Presentation Show/Hide Abstract The simultaneous presence of time-reversal symmetry and spatial inversion symmetry imposes a two-fold degeneracy of the bands structure of a solid. Typically, the lifting of this degeneracy in centrosymmetric materials is indicative of long-range magnetization. However, correlated alignment of spins, even in a paramagnetic sample, is also capable of lifting the spin-degeneracy of the electronic states. We report the observation of parallel dispersing split bands in Eu-ternary pnictide EuZn2Sb2 through the use of high-resolution ARPES. Our DFT calculations account for the observed splitting by including the effects of long-range ferromagnetic correlation of the spins. These results indicate the possibility of observing further time-reversal violating physics in non-magnetic materials.
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Abstract Number: ANPA2023-N00052 Presenting Author: Iftakhar Presenter's Affiliation: Bin Elius Title: Observation of charge density wave induced gap openings in EuTe4 Location: Virtual Presentation Show/Hide Abstract Charge density wave (CDW) state in materials captivates tremendous research interests due to its interference and coexistence with superconductivity. RTen ( R= rare-earth) family is well known for hosting CDW, but unlike n= 2 or 3, EuTe4 has both Te bi- and monolayer nets, making this material an ideal platform to study the interplay between the band features of these two coexisting layers. Here, we present the electronic band structures of EuTe4 using angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations. We have observed not only a CDW gap opening that spans all over the Fermi level, other modulation induced gap opening was observed at lower binding energies as well. Our detailed ARPES based studies discern the directional dependence of the anisotropic CDW gap all over the momentum space and the physics of band interactions at lower energies. Results in this paper provide a fundamental understanding of the band structure of RTe4 sub-family, which paves the way for further exploration of this system.
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Abstract Number: ANPA2023-N00045 Presenting Author: Sitaram Byahut (Invited) Presenter's Affiliation: Central Department of Physics, Nepal Title: Physics in the 21st Century – A personal Perspective Location: Central Department of Physics, T.U., Nepal Show/Hide Abstract In this presentation I will present major achievements up till now and my personal view on major problems and possible future directions in physics. In my personal opinion I will describe king of physics – Astrophysics and Cosmology, the queen – high energy particle physics, and the subjects – all other parts of physics.
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Abstract Number: ANPA2023-N00044 Presenting Author: Hari Prasad Lamichhane (Invited) Presenter's Affiliation: Central Department of Physics, Nepal Title: Developing Curiosity of Performing Experiments Location: Central Department of Physics, T.U., Nepal Show/Hide Abstract Science has tremendous role in the development of the modern age. There are at least two pillars of the science namely: theory and experiment. Both help each other to test their validity and for the creation of another new one. In addition, high speed capacity computers have emerged computational field of research that many people are involved in present days.
No matter how many models and theories are developed, they will be incomplete unless they are tested experimentally. It means that a theory merely predicts the nature with some limited frameworks. That is, there are many phenomena going on in the nature which can be explored by performing appropriate experiments. Though much tedious and expensive job is the experimental research in comparison to the theoretical and computational research, it is essential to develop efficient devices or material products. Therefore, attracting young scientists towards experimental research is one of the major problems which can be solved through motivating them by highlighting the beauty of experiments towards learning the nature.
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Abstract Number: ANPA2023-N00046 Presenting Author: Chhabi Lal Gnawali Presenter's Affiliation: Department of Applied Sciences and Chemical Engineering, Pulchowk Campus, Institute_x000D_ of Engineering (IOE), Tribhuvan University, Lalitpur, Nepal Location: Central Department of Physics, T.U., Nepal Show/Hide Abstract High surface area nanoporous activated carbon materials synthesized from natural carbon sources such as biowaste with large porosity and well-defined pore structures are preferred as electrode materials for high-performance supercapacitors. Here we report the fabrication of novel nanoporous activated carbon material from Phyllanthus emblica (Amala) seed stones by the chemical activation using potassium hydroxide (KOH) as an activator at different carbonization temperatures (700-1000 °C) under the nitrogen gas atmosphere. The precursor and the prepared carbon materials were characterized by the thermogravimetric analysis (TGA), Fourier transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Nitrogen adsorption-desorption isotherms estimated the specific surface area, pore size distribution, and average pore size. The total specific surface area ranges from 1360 to 1946 m2 g-1, and the total pore volume ranges from 0.664 to 1.328 cm3 g-1. The electrochemical energy storage performance was studied by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) in an aqueous 1 M sulfuric acid (H2SO4) solution in a three-electrode cell set up. The specific capacitance of the sample with best surface area was found to be 272 F g-1 at a current density of 1 A g-1 followed by 60% capacitance retention at a high current density of 50 A g-1. Additionally, the electrode showed outstanding cycle performance of 98 % after 10,000 charging/discharging cycles. These results indicate that the prepared nanoporous activated carbon material from Phyllanthus emblica seed stones led to the excellent supercapacitor electrode material for high-energy-storage supercapacitor applications.
Keywords: Phyllanthus emblica seed, KOH activation, nanoporous activated carbon, electrochemical measurement, supercapacitor
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Abstract Number: ANPA2023-N00049 Presenting Author: Abin shakya Presenter's Affiliation: School of Electrical Engineering and Computer Science, Louisiana State University, Baton Rouge, LA 70803, USA Location: Florida International University, FL, USA Show/Hide Abstract To gain insights into the chemical evolution of Earth during its accretion phase, we use first-principles molecular dynamics to simulate a mixed metallic liquid-silicate magma ocean system. Our simulation considers a composition resembling that of the bulk Earth, comprising of four major elements: Fe, Mg, Si, and O in the amounts of 35.7, 19.0, 15.2, and 30.2 wt.%, respectively. We simulate the supercell containing Fe85Mg104Si72O251 under high pressure-temperature conditions (30-40 GPa and 3000-4000 K). By performing coordination/bonding and space-decomposition analyses along with interactive visualization of the atomic position-time series, we predict a chemical phase separation within the simulated melt system. This separation leads to the formation of an iron-rich region, corresponding to the metallic core, and an iron-poor region, corresponding to the silicate mantle. The estimated composition of the iron-rich phase consists of 89.0, 1.1, 4.8, and 5.1 wt.% of Fe, Mg, Si, and O, respectively. Conversely, the corresponding elemental proportions in the magma ocean phase are approximately 8.7, 29.2, 19.8, and 42.3 wt.%, resembling a pyrolytic mantle. Furthermore, we conduct simulations and analyses to examine the incorporation of two important volatile elements, H and N, within the metal-magma ocean system. Our preliminary analysis suggests that both elements exhibit a preference for partitioning into the liquid metal compared to the silicate magma ocean.
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Abstract Number: ANPA2023-N00050 Presenting Author: Amar B Karki Presenter's Affiliation: Scientific Instruments Inc. Title: SI Temperature Probes for Cryogenic field Location: Florida International University, FL, USA Show/Hide Abstract SI Temperature Probes for Cryogenic field
Amar B Karki
Scientific Instruments Inc
Email: akarki@scientificinstruments.com
Abstract
Measurement of Physical properties such as temperature, pressure, density is key to the Industries, Medical facilities, Space Shuttles and Research Institutions. Since 1967, Scientific Instruments (SI) has been a leader in the production of instruments such as Temperature probes and Density meters. SI is committed to our goals and vision to be the worldwide leader in cryogenic measurement technology through continued innovation and advancements in technology.
In this presentation, I will discuss on the SI products and selection of a suitable sensor based on application, temperature range, sensitivity, response time, stability, and packaging. Ruthenium Oxide Temperature Sensors are thick film resistors which adhere to are available with calibration down to 20mK or grouped/interchangeable. The ruthenium oxide temperature sensor offers excellent performance characteristics in magnetic field environments. The SI Silicon Diode Temperature Sensors operate over a wide temperature range (1.5K to 500K) and are miniature in size. They are linear over a wide temperature range interval, have high sensitivity in their lower range, and are interchangeable to a standard V/T curve.
We recently introduced Zirnox sensor which is made of a thin film of zirconium oxynitride. This is a resistive temperature sensor that can operate over a wide temperature range (20 mK to 420K), exhibits negligible calibration shifts when exposed to magnetic field and ionizing radiation environments. SI offers a variety of temperature probes that allow mounting in hazardous environments. These units are constructed of stainless steel, hermetically sealed, and the sensing element is mounted in a thermal epoxy at the tip. The probes are designed for direct immersion or thermowell applications.
The SI-7000 LTD is the most dependable solution for level, temperature, and density profiling in LNG & LPG Storage Tanks.
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Abstract Number: ANPA2023-N00048 Presenting Author: Bashu Dev Khanal Presenter's Affiliation: Old Dominion University Location: Florida International University, FL, USA Show/Hide Abstract A significant source of residual losses in superconducting radiofrequency cavities is the magnetic field trapped during the cooldown due to the incomplete Meissner effect. In this contribution, we present the results of combined magnetic and temperature mapping measurements at 2 K on a single cell niobium cavity resonating at 3.0 GHz. A local magnetic field was produced at different locations near the cavity surface during cooldown, resulting in hot-spots and allowing estimating the contribution to radiofrequency losses due to trapped vortices.
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Abstract Number: ANPA2023-N00047 Presenting Author: Nishchal Thapa Magar Presenter's Affiliation: George Mason University Title: Atomistic simulation of dislocation nucleation in defect-free copper nanoparticles Location: Florida International University, FL, USA Show/Hide Abstract It is well-known that materials become increasingly stronger as their dimensions are reduced to the sub-micrometer scale and even stronger on the nanometer scale. While the “smaller is stronger†paradigm is widely accepted, the exact mechanisms behind the high strength of nanometer-scale objects remain elusive and call for further investigations. In particular, defect-free metallic nanoparticles often demonstrate compressive strength approaching the theoretical strength of the material. The underlying plasticity mechanism in such particles is believed to be related to the nucleation of lattice dislocations on the particle surface. In this work, we applied large-scale molecular dynamics simulations to better understand the onset of plastic deformation in Cu nanoparticles. Single-crystalline nanoparticles with diameters ranging from 17 to 90 nm had smoothed Wulff shapes and were deformed by simulated compression normal to the (111) facets. The particle strength increased with decreasing diameter, reaching about 26 GPa for the smallest size tested. The plastic deformation was initiated by the nucleation of a single dislocation or a group of dislocations on either the top or bottom facet of the particle, usually near a facet corner. Two nucleation mechanisms were identified. In the first mechanism, a Shockley partial half-loop nucleated at the surface after multiple nucleation attempts. After the nucleation of a trailing partial, the full dislocation rapidly traversed the nanoparticle resulting in the nucleation of multiple additional dislocations and a stress drop. In the second mechanism, a partial dislocation loop nucleated under the surface homogeneously and grew on a (111) plane near parallel to a top or bottom facet. The loop eventually reached the particle surface and caused an avalanche of new dislocations and a stress drop. This work has clarified the atomic-scale mechanisms of dislocation-controlled plasticity in nanoscale materials.
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Abstract Number: ANPA2023-N00051 Presenting Author: Puskar Chapagain Presenter's Affiliation: Southern Arkansas University Title: Unlocking the Potential: Harnessing Metallic Particle Doping to Fine-Tune the Bandgap of TiO2 Location: Florida International University, FL, USA Show/Hide Abstract Titanium dioxide (TiO2) holds immense potential as a semiconductor material for a variety of applications such as solar cells, photocatalysis, sensors, and electronics. The increasing interest in TiO2 lies in its optoelectronic properties, which could be heavily influenced by its bandgap. As such, the ability to fine-tune the bandgap of TiO2 is of utmost importance to enhance its properties for specific uses. One of the most widely employed methods involves doping TiO2 with metal particles, resulting in a modification of its inherent bandgap. Consequently, leads to improved performance and expands the range of potential applications. Within this project, we intend to investigate the manipulation of TiO2's bandgap, utilizing UV-Vis spectroscopy, and explore the intricate relationship between different doped elements and the resulting band structure.
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Abstract Number: ANPA2023-N00056 Presenting Author: Tom N. Oder (Invited) Presenter's Affiliation: Department of Physics and Astronomy, Youngstown State University, One University Plaza, Youngstown, OH Title: WaitingSemiconductor Materials for Photonic and Electronic Applications Location: Virtual Presentation Show/Hide Abstract Semiconductor materials have played a huge role in advancing today’s technology through the electronic and photonic devices ushered in over the years. Since about 1990s, wide bandgap compound semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) were the focus of research and development to complement and sometimes replace devices based on silicon (Si), germanium (Ge) and gallium arsenide (GaAs) materials. This rapid development was driven in part by society’s growing needs for devices to handle higher power, higher temperature and higher frequency. Current research efforts are expanding to ultra-wide bandgap semiconductors such as AlGaN, diamond, BN, Ga2O3 and oxide-based materials. In this talk, I will highlight our past work on the III-nitride materials for photonic applications including improvement of light extraction using photonic crystals. I will then present results of our recent work on SiC Schottky barrier diodes for high temperature and high-power electronic applications. The Schottky diodes were fabricated using a variety of rectifying contacts including refractory metal diborides, Ni, Ti and Mo. I will also present results from our efforts on oxide semiconductor materials including ZnO and Ga2O3, where we are investigating the microstructure and optical properties of the thin films deposited and processed under various conditions. The overall goal of our work is to realize the unique advantages expected from the theoretically predicted properties of these (ultra) wide bandgap semiconductor materials.
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Abstract Number: ANPA2023-N00093 Presenting Author: Mim Lal Nakarmi (Invited) Presenter's Affiliation: Brooklyn College, Brooklyn, NY 11210 Title: Exploring Wide Bandgap Semiconductors in My Academic Journey from Banepa to Brooklyn Location: Virtual Presentation Show/Hide Abstract Wide bandgap materials with bandgap wider than 3 eV are technologically important materials for high temperature/power/frequency electronic devices, and for efficient light emitters. In this talk, I will discuss the progress and my contribution in the development of wideband gap materials, especially in III-nitrides for optical applications in the deep UV region during my Academic Journey from Banepa to Brooklyn._x000D_
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Bandgap of AlGaN alloy can be increased systematically from ~ 3.4 to 6.1 eV by increasing aluminum content. AlGaN alloys of Al content > 60% is required for deep UV applications. A binary point in the nitride system, aluminum nitride (AlN), was chosen as the reference for the growth of Al-rich AlGaN alloys. Three-step growth technique was developed using the metal organic chemical vapor deposition to grow high quality AlN thin films on sapphire substrate. Growth of Al-rich AlGaN alloys has become a routine practice after the demonstration of reduced dislocation density of the materials when grown on AlN template. Achieving both n- and p-type conductivity is essential for optical devices such as light emitting diodes (LEDs). Increasing activation energy of the dopants with Al content and compensating point defects are challenges for enhancing conductivity in Al-rich AlGaN alloys. Heavy doping technique was used to achieve highly conductive n-type AlGaN by Si-doping. Recently, p-type AlGaN was also demonstrated in thin films grown on AlN bulk substrate by Mg-heavy doping._x000D_
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In last decade, other materials such as zinc oxide, boron nitrides were also explored as alternative to the nitride. However, doping on these materials is still a challenge for reliable conductivity of both types. Thus, AlGaN alloy has become a unique material for deep UV applications. Recently, wide bandgap materials are also emerged as potential materials as host of single photon emitters. Current work on the h-BN materials and its atomic-like emissions will also be discussed.
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Abstract Number: ANPA2023-N00053 Presenting Author: Peshal Pokharel Presenter's Affiliation: Central Department of Physics, Tribhuvan University, Nepal Title: First-principles study of Structural, Electronic and Elastic Properties of ZrSiO3 Slab Model Location: Virtual Presentation Show/Hide Abstract Abstract
In the present work, the structural, elastic, and electrical properties of ZrSiO3 perovskite were investigated using density functional theory. The full-potential linearized augmented plane wave with the generalized gradient approximation (GGA) for the exchange-correlation potential was applied in quantum espresso codes in order to calculate the above-mentioned properties. The stress-strain method was used to determine elastic parameters such as elastic constants, bulk modulus, shear modulus, and Young’s modulus. The mechanical stability of the compound was confirmed, exhibiting ductile behavior with an anisotropy factor greater than 1. The elastic modulus of the SiO2-terminated slab model is similar to that of natural bone. To assess the thermal behavior, the Debye temperature was calculated using average sound velocity analysis. This analysis provided insights into how the material responds to changes in temperature. Furthermore, the electronic properties of the ZrSiO3 slab model were investigated through band structure analysis and total projected density of states calculations. For bulk, ZrO, and SiO2 terminations, the calculated indirect band gap values were found to be 2.661 eV, 2.585 eV, and 1.639 eV, respectively. The specific surface termination influenced the energy levels of the material, potentially affecting its electronic and optical properties. The study also employed electron density maps to examine the bonding characteristics of the material. Si-O bonds exhibited a partial covalent character, while Zr-O bonds displayed low covalentity. Overall, this study provides valuable insights into the structural, electronic, and elastic characteristics of ZrSiO3. The SiO2-terminated slab model demonstrated promise as a potential scaffold material for bone tissue engineering due to its low band gap and pore size of 105.39 micrometers, which is comparable to natural bone. However, a comprehensive evaluation of all relevant properties is necessary to determine its overall suitability for this specific application.
Keywords: perovskite materials, slab model, band structure, 2D layered perovskite.
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Abstract Number: ANPA2023-N00062 Presenting Author: Dinesh Thapa Presenter's Affiliation: North Dakota State University Title: Optical Trion Trapping in sp3 Defect Single Walled Carbon Nanotube (SWCNT) Location: Virtual Presentation Show/Hide Abstract We present the photoluminescent properties of trions trapped within the quantum well originated by the formation of sp3 defect via organic molecule functionalization in semiconducting single walled carbon nanotube (SWCNT). Trion is the three-body charged exciton, bound state which offers unique properties by manipulating charge, spin, and excitation in one dimensional SWCNT. We employed a model of periodic nanotube covalently functionalized with aryl molecule incorporating sp3 defect using the PBE and B3LYP exchange functionals within the plane wave basis sets. We predicted the trions in excited states are optically active than the excitons with more red-shifted lowest lying transition emitting single photon within the wavelength of optical communication band (1500-2000 nm). Our findings open possibilities for exploiting trions of SWCNT in optoelectronics, ranging from photovoltaics, bio-imaging, telecommunication, and quantum technology.
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Abstract Number: ANPA2023-N00069 Presenting Author: Mazharul Islam Mondal Presenter's Affiliation: University of Central Florida Title: Observation of 3D Dirac state in antiferromagnetic topological material EuMg2Bi2 Location: Virtual Presentation Show/Hide Abstract Topological Dirac semimetals, systems containing low energy relativistic Dirac quasiparticle excitations, have received ample attention in condensed matter physics. Early work on Dirac semimetals focused on nonmagnetic systems with the presence of time reversal symmetry. Recent interest has turned toward the study of magnetic Dirac materials. Here, we have performed electrical resistivity, magnetization, and specific heat capacity measurements of an Eu-ternary pnictide EuMg2Bi2 and confirm the existence of antiferromagnetic ordering below the temperature of 6.7 K. Furthermore, we have studied the electronic structure of EuMg2Bi2 by utilizing high-resolution angle-resolved photoemission spectroscopy (ARPES) which is supplemented by first-principles calculations. Our ARPES measurement reveals the electronic structure of this system is dominated by linearly dispersive hole-like bands near the Fermi level. Our first principles calculations show excellent agreement with these observations. Our results also suggest the presence of a single Dirac cone above the experimental Fermi level. These findings open a platform to study the interplay between topology and magnetism.
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Abstract Number: ANPA2023-N00055 Presenting Author: Mackenzie Songsart-Power Presenter's Affiliation: Department of Physical and Applied Sciences, University of Houston-Clear Lake Location: Virtual Presentation Show/Hide Abstract We report surface-enhanced Raman scattering (SERS) activities of 2D Niobium Carbide (Nb2CTX) MXene measured with a laser excitation of 532 nm, using methylene blue (MB) and crystal violet (CV) as probe molecules. The results showed that the Raman enhancement of the dye molecules on Nb2CTX-based SERS platform was heavily dependent on the laser-molecule combination, giving a higher Raman enhancement for CV than for MB at 10-4 M concentration. A significant difference in the Raman enhancement for two dyes indicates a possibility of selective SERS sensing on 2D Nb2CTX. The results clearly infer that the charge transfer interaction plays a major role in the SERS mechanism. Our findings provide an insight into the development of inexpensive, and selective SERS platforms based on 2D MXenes for molecular detection
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Abstract Number: ANPA2023-N00073 Presenting Author: Tej Bahadur Limbu Presenter's Affiliation: University of Houston-Clear Lake Location: Virtual Presentation Show/Hide Abstract Two-dimensional (2D) molybdenum ditelluride (MoTe2) is a promising platform for surface-enhanced Raman scattering (SERS) applications, due to its excellent electronic properties. Herein, we demonstrate a highly sensitive SERS-based molecular sensing on chemical vapor deposition (CVD)-synthesized 2H- and 1T’-MoTe2 films, using methylene blue (MB) as a probe molecule. Our results show that Raman enhancement on 1T’-MoTe2 is three times higher than that on 2H-MoTe2, and the 1T’-MoTe2 film is an efficient Raman-enhancing substrate that can be used to detect MB at nanomolar concentrations. Our study imparts knowledge on the significance of a suitable combination of laser excitation energy and molecule-material platform for achieving ultrasensitive SERS-based chemical sensing.
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