SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 59: Poster Session: Topology

TT 59.14: Poster

Donnerstag, 30. März 2023, 15:00–18:00, P2/OG4

Pressure-dependent structural instabilities and transport phenomena in candidate topological semimetal LaSb₂ — •Theodore Weinberger, Christian de Podesta, Jiasheng Chen, Stephen Hodgson, and Malte Grosche — Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom

At low temperatures, and in the presence of large magnetic fields, LaSb₂ exhibits large, linear, non-saturating magnetoresistance, defying Fermi liquid behaviour. This phenomenon is thought to be caused by the onset of charge density wave order (CDW) below a sharp, hysteretic anomaly seen in resistivity data at ∼ 355 K. This anomaly is rapidly pushed to lower temperatures under applied hydrostatic pressure, where above 6 kbar, it is fully suppressed. Surprisingly, the anomalous magnetoresistance persists to pressures beyond 20 kbar even after the suppression of the resistive anomaly. Hence, we suggest that the magnetoresistance is not driven by the onset of CDW order. Instead, we propose that the high temperature anomaly corresponds to a structural transition, similar to that seen in CeSb₂, which is supported by ab initio density functional theory calculations. Further, these calculations indicate that the Fermi surface of LaSb2 contains small pockets in both its high and low pressure structures. Small Fermi surface pockets suggest that LaSb₂’s band structure might feature topological, Dirac-like, cones which may explain the observed large, linear magnetoresistance.