Itinerant electron magnetism of η-carbides Co6M6C and Ni6M6C (M=Mo and W)

Abstract

Magnetic, transport, and thermal properties of metallic η-carbides Co6M6C and Ni6M6C (M = Mo and W) with the cubic Ni6Mo6C-type structure have been characterized. The Ni-based compounds Ni6Mo6C and Ni6W6C are Pauli paramagnets with temperature-independent susceptibilities. Susceptibilities of the Co-based compounds Co6Mo6C and Co6W6C are enhanced and temperature-dependent. Co6Mo6C remains paramagnetic down to the lowest temperature, while Co6W6C undergoes an antiferromagnetic-type transition at 46 K. A metamagnetic transition was observed for Co6W6C at 20–30 T at the lowest temperatures. The correlation among the enhancements in the susceptibility, the resistivity, and the electronic specific heat suggests the presence of moderate electron correlation in these compounds.