The Hall effect in quantum critical CeAuSb2

Abstract

CeAuSb2 forms in a two-dimensional structure type with plates of CeSb2 separated by layers of Au and Sb atoms respectively. Kondo effect and moderate heavy fermion characteristics are evident. Antiferromagnetic order occurs at low temperature with magnetic moments along the interplanar [001] direction. We have established TN = 5.6 K from B = 0.01 T, B || c Squid magnetometric measurements. The same field orientation presents furthermore metamagnetic behaviour at Bmeta1 = 2.6 T and at Bmeta2 ≊ B = 5.4 T, as was also previously reported in the literature. It is known that continuous suppression of the magnetic order at TN by applied field leads to a quantum critical point at a critical field Bc = 5.4 T. Here we present and discuss results of Hall effect measurements up to applied fields of 14 T on single-crystal CeAuSb2, a property that offers the possibility to distinguish between types of quantum criticality. Analysis of the field-dependent Hall effect show a jump in the Hall resistivity close to Bc, the temperature dependence of which suggests that for CeAuSb2 the jump evolves into a discontinuity at T = 0 K, B = Bc . Our results are interpreted in terms of local-moment quantum criticality in CeAuSb2.