Phys. Rev. B 68, 165408 (2003)

R. Ocaña, P. Esquinazi, H. Kempa, J. H. S. Torres and Y. Kopelevich 

Abstract

We report on the magnetic field (0T<~B<~9T) dependence of the longitudinal thermal conductivity κ(T,B) of highly oriented pyrolytic graphite in the temperature range 5K<~T<~20K for fields parallel to the c axis. We show that κ(T,B) shows large oscillations in the high-field region (B>2T) where clear signs of the quantum-hall effect are observed in the Hall resistance. With the measured longitudinal electrical resistivity we show that the Wiedemann-Franz law is violated in the high-field regime.