Single-crystal experiments on EuMo₆S₈ and EuMo ₅WS₈

Resistivity measurements have been made on EuMo6S8 and EuMo5WS8 single crystals in the temperature range 1.5-300 K under pressures between ambient and 20 kbar. In contrast to the recently reported results on sintered or melted material, the resistivity has a metallic behavior. No semiconductor behavior is observed in either type single crystal. The strong scattering effects lead to an electronic mean free path equal to the interatomic Mo-Mo distance. The possibility of spin fluctuations associated with the molybdenum atoms is discussed. The superconductivity appears in either type crystal at about the same pressure (10 kbar).