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Title: Wiedemann-Franz law and nonvanishing temperature scale across the field-tuned quantum critical point of YbRh2Si2

The in-plane thermal conductivity kappa and electrical resistivity rho of the heavy-fermion metal YbRh2Si2 were measured down to 50 mK for magnetic fields H parallel and perpendicular to the tetragonal c axis, through the field-tuned quantum critical point H-c, at which antiferromagnetic order ends. The thermal and electrical resistivities, w L0T/kappa and rho, show a linear temperature dependence below 1 K, typical of the non-Fermi-liquid behavior found near antiferromagnetic quantum critical points, but this dependence does not persist down to T = 0. Below a characteristic temperature T-star similar or equal to 0.35 K, which depends weakly on H, w(T) and rho(T) both deviate downward and converge as T -> 0. We propose that T-star marks the onset of short-range magnetic correlations, persisting beyond H-c. By comparing samples of different purity, we conclude that the Wiedemann-Franz law holds in YbRh2Si2, even at H-c, implying that no fundamental breakdown of quasiparticle behavior occurs in this material. The overall phenomenology of heat and charge transport in YbRh2Si2 is similar to that observed in the heavy-fermion metal CeCoIn5, near its own field-tuned quantum critical point.
 [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [3]
  1. Universite de Sherbrooke
  2. Ames Laboratory
  3. Brookhaven National Laboratory
Publication Date:
OSTI Identifier:
Report Number(s):
IS-J 8270
Journal ID: ISSN 1098-0121
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 89
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE metals, phase-transition, superconductivity