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

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.

► Metallic magnetism of η-carbide-type compounds (Co6Mo6C, Co6W6C, Ni6Mo6C and Ni6W6C) was studied.
► Ni-based compounds show Pauli paramagnetic behavior.
► Co6Mo6C shows Curie–Weiss-type susceptibility.
► Co6W6W is an itinerant antiferromagnet with TN=46K.