Dresden 2020 – wissenschaftliches Programm
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TT 59.8: Vortrag
Donnerstag, 19. März 2020, 17:00–17:15, HSZ 03
Unusual phase boundary of the magnetic-field-tuned valence transition in CeOs4Sb12 — •Kathrin Götze1, Matthew Pearce1, Paul Goddard1, Marcelo Jaime2, M. Brian Maple3, Kalyan Sasmal3, Tatsuya Yanagisawa4, Alix McCollam5, Thomas Khouri5, Pei-Chun Ho6, and John Singleton2 — 1University of Warwick, Coventry, UK — 2National High Magnetic Field Laboratory, Los Alamos, USA — 3University of California, San Diego, USA — 4Hokkaido University, Sapporo, Japan — 5High Field Magnet Laboratory (EMFL), Nijmegen, NL — 6California State University, Fresno, USA
The H-T phase diagram of the filled skutterudite CeOs4Sb12 was mapped out in magnetic fields up to 60 T by resistivity, magnetostriction, and MHz conductivity. The semimetallic low-H, low-T L phase and the metallic high-H, high-T H phase are separated by a valence transition which – opposing the “elliptical” text-book behaviour for which H2 ∝ T2 – exhibits a boundary with an almost wedge-like shape with a non-monotonic gradient that alternates between positive and negative. We ascribe the unusual behaviour of the phase boundary at low T to the presence of additional energy scales associated with a quantum critical point. Field-dependent, increasing effective masses derived from quantum oscillations close to the intersection of L, H and the ordered spin-density wave phase are interpreted as indicators of this quantum criticality. The high-T, low-H portion of the phase diagram may instead be associated with the proximity of CeOs4Sb12 to a topological semimetal phase induced by uniaxial stress.