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

Abstract

Magnetic, transport, and thermal properties of metallic η-carbides Co 6 M 6 C and Ni 6 M 6 C (M = Mo and W) with the cubic Ni 6 Mo 6 C-type structure have been characterized. The Ni-based compounds Ni 6 Mo 6 C and Ni 6 W 6 C are Pauli paramagnets with temperature-independent susceptibilities. Susceptibilities of the Co-based compounds Co 6 Mo 6 C and Co 6 W 6 C are enhanced and temperature-dependent. Co 6 Mo 6 C remains paramagnetic down to the lowest temperature, while Co 6 W 6 C undergoes an antiferromagnetic-type transition at 46 K. A metamagnetic transition was observed for Co 6 W 6 C 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.