Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session UU09: V: Optical and Electronic Materials Physics |
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Sponsoring Units: FIAP Chair: Michael Leuenberger, University of Central Florida Room: Virtual Room 9 |
Wednesday, March 22, 2023 5:00AM - 5:12AM |
UU09.00001: Temperature-dependent and symmetry-enforced dynamical matrices of silicon by non-perturbative MD simulations David E Crawford Within the framework of the phonon Boltzmann transport equation (phonon BTE), the accuracy of the predicted phonon-mediated lattice thermal conductivity (κLatt) relies on the fidelity of phonon spectra and phonon-phonon scattering matrices. In practice, the temperature independent, or bare, harmonic force constant matrices are often adopted. To quantitatively study phonon frequency renormalization up to the melting temperature, we have implemented a robust numerical algorithm to compute temperature-dependent and symmetry-enforced phonon dynamical matrices for all the q-points in the first Brillouin zone of reciprocal space. This method includes contributions of all orders of lattice anharmonicity without any perturbation approximations. Here, we will report our recent results of phonon dynamical matrices of silicon crystals from 300K to 1500K utilizing a machine learning interatomic potential of silicon. We will present a systematic comparison between the phonon BTE predicted temperature dependence in κLatt using either the original bare-phonon dynamical matrices or the current renormalized phonon dynamical matrices. |
Wednesday, March 22, 2023 5:12AM - 5:24AM |
UU09.00002: Multiple lattice collapses in the family of SrNi2P2 Adrian Valadkhani, Shuyang Xiao, Seok-Woo Lee, Paul C Canfield, Roser Valenti Recently, it was discovered that SrNi2P2 has a high recoverable strain rate of ~14%, which is very stable against repetition[1]. Common values for such strain rates are less than one percent and limited by plastic deformation or fracture. For SrNi2P2, a double lattice collapse was proposed as the underlying mechanism. We perform ab initio density functional theory calculations for AT2X2 (A = (earth) alkaline, T = transition metal, X = atom of the C or N group) under various strain conditions and find that the strain-free ground state exists in an orthorhombic unit cell in which both collapsed and uncollapsed P-bonds are present. Upon strain, a structural transition to a tetragonal unit cell of the ThCr2Si2 family occurs. This transition occurs not only by compressive but also by tensile strain, where a change in the hybridization of the P atoms forms either collapsed or uncollapsed bonds respectively. We will discuss comparisons with experimental observations. [1] S. Xiao et al. Nano Lett. 2021, 21, 19, 7913–7920
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Wednesday, March 22, 2023 5:24AM - 5:36AM |
UU09.00003: Electrochemical Li intercalation and high-pressure response in b-AsyP1-y alloys: In-situ Raman spectroscopy study Dinushika Vithanage, Manthila Rajapakse, Usman Abu, Jacek Jasinski, Gamini Sumanasekera Structural evolution of black Arsenic-Phosphorous (b-AsyP1-y) alloys with varying Arsenic concentrations were studied under Li intercalation and high-pressure via in-situ Raman spectroscopy. When subjected to electrochemical Li intercalation, a monotonic red shift was observed in all Raman peaks during the initial stage of intercalation due to donor-type charge transfer from Li to b-AsyP1-y. Above an intercalation threshold, emergence of a new peak, identified as the Eg mode of gray-As with a rhombohedral crystal structure (in contrast to orthorhombic structure of b-AsyP1-y) was observed undergoing a blue shift, implying hardening of phonon modes due to transformation to a new phase. Further lithiation exhibited a red shift in all Raman modes due to donor type charge transfer to the new structure. Next, b-AsyP1-y alloys were subjected to high pressure using a Diamond Anvil Cell (DAC). A pressure induced monotonic blue shift was observed in all the Raman modes in these alloys indicating phonon hardening. A partial phase restructuring was observed ∼9 GPa in b-As0.6P0.4 with the emergence of the Eg mode of Gray-As and undergoing a blue shift up to ∼9 GPa. b-As0.8P0.2 is believed to undergo a complete phase transition around 9 GPa showing a significant change in its Raman spectrum with a dominant Eg mode of Gray-As and diminished P-P peaks. |
Wednesday, March 22, 2023 5:36AM - 5:48AM |
UU09.00004: Resolving Conflicts in Rhenium Dichalcogenides (ReS2 and ReSe2) MD NUR HASAN, Felix Sorgenfrei, Nivedita Pan, Samir Kumar Pal, Anna Delin, Patrik Thunstrom, D. D. Sarma, Olle Eriksson, Debjani Karmakar The absence of consensus regarding the correct structure of two-dimensional rhenium dichalcogenides (ReS2 and ReSe2) with distorted 1T′ structures is the source of numerous conflicts between their theoretical and experimental results. Maximal prior studies have dealt with the structures predicted by Murray et al. and Wildervanck et al. for ReS2 and ReSe2 respectively and have overlooked the structural rectification suggested by Lamfers et al. With the help of first principles calculations, we have extensively investigated the comparative energetics and electronic properties of all available structures to conclude about the correct structures, capable of resolving all conflicts about their layer-dependent anisotropic optical properties. The non-iso-structural and non-iso-electronic nature of these two compounds indicate that they differ in structural parameters, polyhedral coordination and across-plane electronic hybridization. The pressure-induced metallic transitions are analyzed from detailed electronic band structures and orbital projection analysis implying a 3D and 2D-like behavior for ReS2 and ReSe2 respectively. Next, with the help of a combined full-potential density functional theory and multiplet ligand field theory (DFT+MLFT), the X-ray spectral properties of these new structures are analyzed under both ambient and high-pressure conditions in the light of their intricate differences of non-relaxed versus relaxed optimized structures. |
Wednesday, March 22, 2023 5:48AM - 6:00AM Author not Attending |
UU09.00005: Positronium Lyman-α blueshift in ellipsoidal quantum dots Karen Dvoyan The confined states of a positronium (Ps) in an ellipsoidal quantum dot (QD) are theoretically investigated within the framework of the perturbation theory in two quantum confinement regimes: strong and weak. The expressions for the wave functions and energies of the Ps and independently quantized electron-positron pair are obtained in the weak and strong quantum confinement regimes, correspondingly. It is proved that in the first order of the perturbation theory the energy correction is non-zero and its dependence on ellipticity parameter β is linear. The Ps formation and binding energy dependences on the QD geometric parameters are discussed. Ps Lyman-α blueshift is revealed as a result of the ellipsoidal shape of the QD. |
Wednesday, March 22, 2023 6:00AM - 6:12AM |
UU09.00006: An investigation on the plasmonic behavior of Coulomb coupled heterostructure of silicene and graphene. Dipendra Dahal Extensive research on the study of plasmonic behavior of a combination of graphene and silicene layers is done. The analytical formulation for the surface response function is first carried out for a general structure which then is numerically evaluated for several combinations of two-dimensional layers and substrates. This laid the foundation for the calculation of the plasmonic mode of the given heterostructure. The obtained expression is used for numerical computation of plasmonic nature for various combinations. The results are presented numerically and interpreted physically. In addition, the rate of decay of the plasmon for different structures is calculated and interpreted physically. Overall the effect of adding the substrate and the role of a variety of 2D layers heterostructure are analyzed. |
Wednesday, March 22, 2023 6:12AM - 6:24AM |
UU09.00007: Probing quantum geometry of semiconductors by optical absorption Antonio Lívio De Sousa Cruz, Matheus S Martins de Sousa, Wei Chen The quantum geometry in the momentum space of semiconductors and insulators, described by the quantum metric of the valence band Bloch state, has been an intriguing issue owing to its connection to various material properties. We show that because the Brillouin zone is a torus for materials in any dimension, the integration of quantum metric over momentum space represents an average distance between neighboring Bloch states, which can further be expressed in real space as a local quantity that we call fidelity marker. A linear response theory is introduced to generalize the fidelity marker to finite temperature, and moreover demonstrates that it can be measured as the local optical absorption rate of linearly polarized light, whose frequency dependence is described by a spectral function. A nonlocal fidelity marker that quantities the overlap between Wannier states is suggested to be a universal indicator of quantum phase transitions at which the quantum metric diverges. The ubiquity of these markers is demonstrated for a variety of topological insulators and topological phase transitions in different dimensions. |
Wednesday, March 22, 2023 6:24AM - 6:36AM |
UU09.00008: Polarization tuneable optical properties in hybrid improper 3d-5d double perovskites from first principles calculations BUVANESWARAN Sathiyamoorthy, Monirul Shaikh, Trilochan Sahoo, Saurabh Ghosh Multiferroic materials with perovskite structure are also promising for photovoltaic devices. In particular, hybrid improper ferroelectric double perovskites, where A-site cation ordering induces microscopic polarization and also can tune the electronic structure for the composition of BB’, are promising because it opens the possibility of tuning the optical properties with electric field. By using Density functional theory calculations and WEIN2K simulations, we have studied the electronic and optical properties of RbA’MnWO6 (A’= La, Y).Here the primary order parameters are rotation (QR+) and tilt (QT) distortions along a0a0c+ and a-a-c0, respectively. By using mBJ potential, the analysis of electronic properties shows the indirect semiconducting band gaps of 2.1eV and 2.4eV for RbY and RbLa which are suitable (Eg< 3.0 eV) for absorption of visible light. Further we discussed the band structure and optical transitions to analyze the optical absorption spectrum.And finally, we have performed molecular dynamics simulations at various finite temperatures to study the temperature dependent electronic and optical properties. In case of RbLaMnWO6 at 600K, (50 picoseconds), we found the dielectric switching will enhance the optical properties in these materials. |
Wednesday, March 22, 2023 6:36AM - 6:48AM |
UU09.00009: Proximity-induced spin-polarized magnetocaloric effect in transition metal dichalcogenides Natalia Cortes, Francisco J Peña, Oscar Negrete, Patricio Vargas We explore proximity-induced magnetocaloric effect (MCE) on transition metal dichalcogenides, focusing on a two-dimensional (2D) MoTe2 monolayer deposited on a ferromagnetic semiconductor EuO substrate connected to a heat source. We model this heterostructure using a tight-binding model, incorporating exchange and Rashba fields induced by proximity to EuO, and including temperature through Fermi statistics and mean-field calculations. The MCE is induced on the 2D MoTe2 layer due to the EuO substrate, revealing large spin-polarized entropy changes for energies out of the band gap of the MoTe2-EuO system. By gating the chemical potential, the MCE can be tuned to produce heating for spin up and cooling for spin down across the K and K' valley splitting in the valence band, whereas heats for both spins in the conduction band up to the EuO Curie temperature. The Rashba field enhances the MCE in the valence zone while decreasing it in the conduction bands. The exchange field-induced MCE could be useful to produce tunable spin-polarized thermal responses in magnetic proximitized 2D materials. |
Wednesday, March 22, 2023 6:48AM - 7:00AM |
UU09.00010: First-principles study of the electronic and optical properties of HoW impurities in single-layer tungsten disulfide Michael N Leuenberger The electronic and optical properties of single-layer (SL) tungsten disulfide (WS2) in the presence of substitutional Holmium impurities (HoW) are studied. Although Ho is much larger thanW, density functional theory (DFT) including spin-orbit coupling is used to show that Ho:SL WS2 is stable. The magnetic moment of the Ho impurity is found to be 4.75μB using spin-dependent DFT. The optical selection rules identified in the optical spectrum match exactly the optical selection rules derived by means of group theory. The presence of neutral HoW impurities gives rise to localized impurity states (LIS) with f-orbital character in the band structure. Using the Kubo-Greenwood formula and Kohn-Sham orbitals we obtain atom-like sharp transitions in the in-plane and out-of-plane components of the susceptibility tensor, Imχ? and Imχ⊥. The optical resonances are in good agreement with experimental data. |
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