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 M24: Emergent Phenomena in Strongly Correlated Quantum MaterialsInvited
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Sponsoring Units: DCMP Chair: Abdelouahad El Fatimy, Mohammed VI Polytechnic University Room: Room 237 |
Wednesday, March 8, 2023 8:00AM - 8:36AM |
M24.00001: Quantum Oscillations in Topological Materials Invited Speaker: Kuan-Wen Chen Magnetic quantum oscillations play a key role in resolving the Fermi surfaces and electronic structures and confirming the prediction of topological materials. In type II Dirac semimetal XAl3(X=V, Nb, Ta) [1], we measured the quantum oscillations in magnetization and determined the angular dependence of their Fermi surface cross-sectional areas, and reveals an excellent agreement with our first-principles calculations. As a result, the quantum oscillations support the existence of tilted Dirac cones with Dirac type-II nodes located at 100, 230, and 250 meV above the Fermi level for VAl3, NbAl3, and TaAl3, respectively. We will further discuss the determination of Berry’s phase via quantum oscillations. |
Wednesday, March 8, 2023 8:36AM - 9:12AM |
M24.00002: From exact solution of Mixed-Valence Impurity to Mixed-Valence Insulators Invited Speaker: Chandra M Varma Several years ago, it was discovered through Wilson renormalization group cal culations [1] and bosonization methods [2] that isolated mixed valence impu rities, unlike Kondo impurities, have a singularity in the limit of zero energy. The excitations in that case can be expressed as a localized Majorana and a propagating Majorana. While a metallic mixed valence lattice does not have the symmetries to allow such excitations, the insulating lattice state may have protection so that such excitations may exist and give rise at low temperatures to specific heat singularity and magneto-oscillations with a large Fermi-surface. The theory for the lattice [3] is approximate and motivated by recent exper iments together with some predictions for future experiments which may add confidence to the ideas or rule them out. |
Wednesday, March 8, 2023 9:12AM - 9:48AM |
M24.00003: Weyl-Kondo semimetals: Phenomena and stabilization mechanisms Invited Speaker: Silke Buehler-Paschen Gapless electronic topology driven by strong correlations is an emerging field of great interest, with heavy fermion compounds at its forefront. I will report on the giant signatures of topology observed in Ce3Bi4Pd3, the material on which experiments [1,2], along with theoretical work on nonsymmorphic lattice models [3], have coined the notion of a Weyl-Kondo semimetal, and on the genuine topology control that can be achieved by magnetic field tuning, leading to the annihilation of the material’s Weyl nodes at moderate magnetic fields [4,5]. I will also discuss design strategies for further correlation-driven topological metals, and point to new candidate materials [6,7]. |
Wednesday, March 8, 2023 9:48AM - 10:24AM |
M24.00004: Magnetotransport of pyrochlore iridate Sm2Ir2O7 across a pressure-induced quantum-critical phase boundary Invited Speaker: Paul A Goddard Rare-earth pyrochlore iridates host two interlocking magnetic sublattices of corner-sharing tetrahedra and can harbour a unique combination of frustrated moments, exotic excitations and highly correlated electrons. We have measured the transport and magnetotransport properties of single-crystal Sm2Ir2O7 up to and beyond the pressure-induced quantum critical point (QCP) for all-in-all-out (AIAO) Ir order at pc = 63 kbar previously identified by resonant X-ray scattering. Contrary to prior predictions, we do not find a crossover from insulating to metallic behavior at low temperatures above pc. Instead, the metal-insulator transition temperature, which tracks the decrease in the AIAO ordering temperature for pressures up to 30 kbar, begins to increase under further application of pressure, pointing to the presence of an as-yet unidentified localization mechanism. The magnetotransport does track the suppression of Ir magnetism, however, with a strong hysteresis observed only within the AIAO phase boundary, similar to that found for Ho2Ir2O7 and attributed to plastic deformation of Ir domains. Around pc we find the emergence of a new type of electronic behavior, characterized by a negative magnetoresistance with small hysteresis at the lowest temperatures, and hysteresis-free positive magnetoresistance above 5 K. A Weyl semimetal phase is predicted to occur in the vicinity of the QCP. The temperature dependence of our low-temperature transport data, however, are found to be best described by a model consistent with a Weyl semimetal across the entire pressure range. |
Wednesday, March 8, 2023 10:24AM - 11:00AM |
M24.00005: Searching for exotic superconductivity on the border of itinerant magnetism Invited Speaker: James Analytis In this talk, I discuss novel correlated magnetism found in layered compounds - specifically intercalated transition metal dichalcogenides. Density functional calculations show a highly unusual Fermi surface structure, and suggest an interplay of local and itinerant magnetism. The proximity of the materials to superconductivity is discussed. Furthermore, we demonstrate the possible control of the magnetic state via electrical stimuli, which could potentially allow access to metastable states. |
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