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SUMMARY:The unusual phase boundary of the magnetic-field-tuned valence tra
 nsition in CeOs4Sb12 - Dr Kathrin Götze\, Department of Physics\, Univers
 ity of Warwick
DTSTART:20191127T111500Z
DTEND:20191127T121500Z
UID:TALK134989@talks.cam.ac.uk
CONTACT:Ellen Smith
DESCRIPTION: CeOs4Sb12\, a member of the filled skutterudite family and cl
 ose relative of the unconventional superconductor PrOs4Sb12\, has a very u
 nusual H-T phase diagram in which the boundary of the valence transition b
 etween the semimetallic low-H\, low-T L phase and the metallic high-H\, hi
 gh-T H phase exhibits an uncommon\, wedge-like shape. Contrary to the “e
 lliptical” text-book behaviour for which H2 is proportional to T2\, the 
 boundary between H and L phase is strongly altered with a non-monotonic gr
 adient that alternates between positive and negative. The phase diagram wa
 s mapped out by resistivity\, magnetostriction\, and MHz conductivity in m
 agnetic fields up to 60 T. We ascribe the unusual behaviour of the phase b
 oundary at low T to the presence of additional energy scales associated wi
 th 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 i
 nstead be associated with the proximity of CeOs4Sb12 to a topological semi
 metal phase induced by uniaxial stress. \n\nIn this talk I will present th
 e experimental results that indicate the boundaries in the phase diagram a
 nd discuss the valence transition in CeOs4Sb12 in context with other Ce an
 d Yb based systems.\n
LOCATION:Mott Seminar Room (531)\, Cavendish Laboratory\, Department of Ph
 ysics
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