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 Y44: Dirac and Weyl Semimetal: TheoryFocus
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Sponsoring Units: DMP Chair: Thais Trevisan, Ames Laboratory Room: Room 316 |
Friday, March 10, 2023 8:00AM - 8:36AM |
Y44.00001: Resistivity anomaly and negative longitudinal magnetoresistance in ZrTe5 Invited Speaker: Bo Fu Demonstrated by the first principles calculation and the angle-resolved photoemission spectroscopy (ARPES) measurement, the transition-metal pentatelluride ZrTe5 is the prototype of massive Dirac material close to the topological critical point. Many exotic and anomalous behaviors of electric and thermoelectric transport were revealed recently in this system. Resistivity in ZrTe5 exhibits a sharp peak at a finite temperature Tp. The peak occurs approximately at a large range of temperatures from 50 to 200K, but the exact value varies from sample to sample. This resistivity anomaly is always accompanied by the sign change of the Hall and Seebeck coefficients around the transition temperature. We propose a theory of quasiparticles to address a series of anomalous behaviors measured in ZrTe5. The negative longitudinal magnetoresistance in this system was observed in a series of experiments by different groups, and was shown the quadratic behavior of the magnetic field. Under pressure, ZrTe5 undergoes a topological phase transition accompanied by the closing and reopening of the band gap. The quadratic coefficient of the magnetoconductivity also varies with the external strain. We propose a quantum magneto-transport theory based on Landau level representation different from the chiral anomaly mechanism to account for the quadratic behavior and the strain dependence of the magnetoconductivity in ZrTe5. |
Friday, March 10, 2023 8:36AM - 8:48AM |
Y44.00002: First principle study of WTe2 from monolayer to bilayer and bulk ke liu We use density functional theory (DFT) to calculate the total energy of a series of monolayer transition metal dichalcogenides, for three phases 1H (hexagonal), 1T (orthorhomibic) and 1T' (orthorhomibic). We find the ground state of MoTe2, CrTe2 and WTe2 is 1T', the energy of which is very close to 1T; for ScTe2, VTe2, ReTe2 the ground state is 1T; for TiTe2 and HfTe2 the ground state is 1H. We verify for WTe2, 1T and 1T' is connected by the band inversion. We calculate the dielectric function of monolayer, bilayer and the bulk Td phase of WTe2, and find the average dielectirc constant (zero frequency limit) increses from 8.08 to 21.82 (bilayer) and 48.6 (bulk), although they have strong anisotropy along a, b and c axis. The software we use is DS-PAW (Device studio-projector augmented wave) developed by Hongzhiwei Technology (Shanghai) Co. Ltd. The Perdew-Burke-Ernzerhof (PBE) exchange-correlation energy functional within the generalized gradient approx imation (GGA) were employed. |
Friday, March 10, 2023 8:48AM - 9:00AM |
Y44.00003: Minimal Model of Two-Band Quadratic Band Crossing Capturing Wave Function Geometry Junseo Jung, Hyeongmuk Lim, Bohm-Jung Yang Quantum metric, along with the geometry of the wave functions has received attention in condensed matter physics. In this work, we propose a simple model which captures full geometrical aspect of the general two-band quadratic band crossing points (QBCPs) with minimal parameters. We divide the parameters of the QBCPs into two categories: the parameters that define the energy dispersion or the geometry of the system. We show that the physical quantities of this two-band system, such as the Berry phase, can be expressed using geometric parameters. Furthermore, we design a lattice model that captures various geometry of the wave functions on the Bloch sphere and demonstrates how the geometry change under the additional symmetries. |
Friday, March 10, 2023 9:00AM - 9:12AM |
Y44.00004: Band Energy Dependence of Defect Formation in the Topological Semimetal Cd3As2 Chase Brooks, Mark van Schilfgaarde, Dimitar Pashov, Jocienne N Nelson, Dan S Dessau, Kirstin M Alberi, Stephan Lany Cadmium Arsenide (Cd3As2) is a prototypical Dirac semimetal that manifests topological properties in a 3D bulk material. In defect-free Cd3As2, the Fermi level EF lies at a minimum in the density of states at the Dirac point, but experimentally it forms with excess electron carriers and an elevated EF, thereby masking the topological features. To computationally study the self-doping of Cd3As2, we combine density functional theory (DFT) calculations for defect formation energies with quasi-particle self-consistent GW (QSGW) electronic structure calculations. We demonstrate an innate dependence of the point defect formation energies on carrier concentrations and use the QSGW calculated density of states to extrapolate formation energies to arbitrary electron concentrations. This approach allows the quantitative modeling of thermodynamic defect equilibria in topological semimetals and is used to predict how Cd3As2 growth conditions affect the position of EF relative to the Dirac point. |
Friday, March 10, 2023 9:12AM - 9:24AM |
Y44.00005: Valley axion field and surface phonon modes in 3D time reversal invariant Dirac materials Abhinava Chatterjee, Chaoxing Liu Axion electrodynamics can emerge in 3D topological materials and plays an essential role in a variety of physical phenomena, including surface half quantum Hall effect, topological magneto-optical response, chiral/helical fermions along dislocations, magnon-polariton, etc. In this work, we consider a thin film of a 3D time reversal invariant Dirac semi metal <!--[if gte msEquation 12]>N style='font-family:"Cambria Math",serif;mso-ascii-font-family:"Cambria Math"; |
Friday, March 10, 2023 9:24AM - 9:36AM |
Y44.00006: Black hole mirages: electron lensing and Berry curvature effects in inhomogeneously tilted Weyl semimetals Andreas Haller, Suraj Hedge, Chen Xu, Thomas L Schmidt, Tobias Meng, Christophe De Beule In this talk, I present our recent study about electronic transport in Weyl semimetals with spatially varying nodal tilt profiles. We discuss two complementary approaches that characterise the electron flow: solutions of the semi-classical equations of motion, in analogy to those encountered in black hole spacetimes, and large-scale microscopic simulations of a scattering region surrounded by semi-infinite leads. We show that the two approaches lead to equivalent results when the wave packet is sufficiently far from the center of the tilt. The two methods are arguably a powerful toolset in the pursuit of tilt-tronic devices such as e.g. electronic lenses. |
Friday, March 10, 2023 9:36AM - 9:48AM |
Y44.00007: Nonlinear Quantum Electrodynamics in Dirac Materials Aydin C Keser, Yuli B Lyanda-Geller, Oleg P Sushkov Classical electromagnetism is linear. However, fields can polarize the vacuum Dirac sea, causing quantum nonlinear electromagnetic phenomena, e.g., scattering and splitting of photons, that occur only in very strong fields found in neutron stars or heavy ion colliders. We show that strong nonlinearity arises in Dirac materials at much lower fields ∼1 T, allowing us to explore the nonperturbative, extremely high field limit of quantum electrodynamics in solids. We explain recent experiments in a unified framework and predict a new class of nonlinear magnetoelectric effects, including a magnetic enhancement of dielectric constant of insulators and a strong electric modulation of magnetization. We propose experiments and discuss the applications in novel materials. |
Friday, March 10, 2023 9:48AM - 10:00AM |
Y44.00008: Revisiting the fate of interacting 3D semimetals in the ultra-quantum limit Nandagopal Manoj, Jason F Alicea Low-carrier-density bulk materials such as Weyl semimetals can enter the ultra-quantum limit—wherein a single Landau level band is populated—at experimentally accessible magnetic fields. In this regime, the interplay between Landau level degeneracy, residual kinetic energy along the field direction, and repulsive interactions has been shown to generate a "self-layering" charge-density wave instability realizing a three-dimensional integer quantum hall state. We revisit the fate of semimetals in the ultra-quantum limit using functional renormalization group techniques, allowing for general symmetry-allowed bare interactions. In addition to the familiar charge density waves, our treatment captures Wigner-crystal-like instabilities in which electrons organize into arrays of "tubes" oriented along the field. We also investigate the stability of the marginal Fermi liquid state previously found to emerge from attractive interactions. |
Friday, March 10, 2023 10:00AM - 10:12AM |
Y44.00009: Computing Symmetry-Protected Band Crossings and Boundary Nodes from Random Matrix Models Hung-Hwa Lin, Daniel P Arovas, Yi-Zhuang You Topological materials protected by symmetry, such as nodal line materials, exhibit distinct characteristics from their non-symmetric counterpart. |
Friday, March 10, 2023 10:12AM - 10:24AM |
Y44.00010: Electronic transport in Weyl semimetals with a uniform concentration of torsional dislocations Enrique Munoz, Daniel Bonilla In this article, we consider a theoretical model for a type I Weyl semimetal, under the presence of a diluted uniform concentration of torsional dislocations. By means of a mathematical analysis for partial wave scattering (phase-shift) for the T-matrix, we obtain the corresponding retarded and advanced Green's functions that include the effects of multiple scattering events with the ensemble of randomly distributed dislocations. Combining this analysis with the Kubo formalism, and including vertex corrections, we calculate the electronic conductivity as a function of temperature and concentration of dislocations. We further evaluate our analytical formulas to predict the electrical conductivity of several transition metal monopnictides, i.e. TaAs, TaP, NbAs and NbP. |
Friday, March 10, 2023 10:24AM - 10:36AM |
Y44.00011: Anomalous electron-phonon coupling in the Kagome ferromagnetic Weyl semimetal Co3Sn2S2 Malhar Kute, Ge He, Leander Peis, Daniel Jost, Emily M Been, Brian Moritz, Ramona Stumberger, Changjiang Yi, Youguo Shi, Andreas Baum, Rudi Hackl, Thomas Devereaux We present a theoretical analysis based on first principles of the Raman response from the magnetic Kagome Weyl semimetal Co3Sn2S2. Two Raman active phonon modes have been identified in A1g and Eg symmetry, with strong electron-phonon coupling (EPC) to the A1g phonon above the ferromagnetic phase transition temperature TC. Density functional theory (DFT) calculations accurately predict the experimentally observed A1g and Eg phonon energies, and the phonon eigenvectors provide insight into the source of the electron-phonon coupling. A phenomenological approach allows us to quantify the observed EPC in the Raman spectrum, while first principles methods allow us to characterize the nature of the EPC for both modes. The strong electron-phonon coupling in A1g can be explained by the asymmetric crystal field felt by the Co atoms: out-of-plane motion of the S atoms results in both intraband and interband EPC, the latter resulting in significant asymmetry in the Raman peak. These results give us a comprehensive understanding of the bulk band structure evolution as a function of temperature in Co3Sn2S2, which paves the way for further study of the driving force of the long-range magnetic order and more emergent effects in this and similar compounds. |
Friday, March 10, 2023 10:36AM - 10:48AM |
Y44.00012: Dominant two-dimensional electron-phonon interactions in the Dirac semimetal Na3Bi Dhruv C Desai, Jinsoo Park, Jin-Jian Zhou, Marco Bernardi Topological Dirac semimetals such as Na3Bi exhibit unconventional transport properties due to their Dirac-like gapless excitations near the Fermi level. A microscopic understanding of charge carrier scattering and transport in these materials remains an outstanding challenge. In this talk, we will present first-principles calculations of electron-phonon (e-ph) interactions and phonon-limited transport in the Dirac semimetal Na3Bi. Our findings reveal that e-ph interactions in Na3Bi are dominated by two-dimensional (2D) shear phonons with momentum in the x-y plane. We explain the origin of these 2D e-ph interactions and analyze their key role in charge transport via mobility and resistivity calculations in the framework of the ab initio Boltzmann transport equation (BTE). To conclude, we will discuss an extension of the ab initio BTE to study (magneto)transport in both Weyl and Dirac semimetals, by including the Berry curvature computed from first principles. |
Friday, March 10, 2023 10:48AM - 11:00AM |
Y44.00013: Topological Features in the Optical Response of Nodal Ring Semimetals Maria Sebastian, Ashutosh K Singh, Po-Yao Chang, Alexey Belyanin
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