Magnetic and transport properties of layered oxysulfides (La1-xCaxO)Cu1-yNiyS (y=O and y=x)

Compounds in the (La1-xCaxO)CuS system show a semiconductive temperature dependence of the electrical conductivity in the solubility range of Ca (0 less than or equal to x less than or equal to 0.15) though its magnitude increases with x. In (La1-xCuxO)Cu1-xNixS, a semiconductor to metal transition is observed at x similar to 0.02, which indicates the introduction of mobile holes into the valence band by the direct substitution of Ni for Cu. A very weak ferromagnetism(similar to 0.06 mu(B)/Ni atom) is observed for x greater than or equal to 0.01, which is not attributed to the Ni metal impurity.