Anomalous low-temperature state of a possible Kondo semimetal Ce Os4 Sb12: Magnetic field and la impurity study

Abstract

Specific heat in magnetic fields to 14 T, magnetic susceptibility and electrical resistivity for single crystalline samples of Ce1-x Lax Os4 Sb12 (x=0,0.02,0.1) are reported. The results of the magnetic susceptibility and electrical resistivity are consistent with a formation of the hybridization gap below 100 K in all investigated alloys. We argue for the intrinsic origin of a large electronic specific heat coefficient and 1.1 K anomaly. The low temperature state is very sensitive to the La alloying. On the other hand, the Kondo temperature and energy gap, extracted from susceptibility and resistance measurements, are unaffected by the alloying. The magnetic phase diagram of the pure compound is presented. © 2006 The American Physical Society.