Doping effect on transport properties of layered oxysulfide Sr ₂Cu₂CoO₂S₂ with CoO₂ square planes

Layered cobalt oxysulfide Sr₂Cu₂CoO₂S ₂ crystallizes in an unusual intergrowth structure which represents a combination of SrCu₂S₂ and SrCoO₂. Sr ₂Cu₂CoO₂S₂ is a p-type antiferromagnetic semiconductor with T_N(= 200 K). And below T _t(= 125 K), the antiferromagnetic nature is changed from 2D to 3D. We studied Seebeck coefficient of Sr₂Cu₂CoO ₂S₂ and its Cu-doped compounds. Their Seebeck coefficients near T, tend to enhance by the Cu-doping into CoO₂ square planes. The curves of the temperature dependence of Sr₂Cu ₂Cu_xCo_1-xO₂S₂ is changed near T_N, and the change points shift to high temperature by Cu-doping. The behavior resembles in T_N shift of the magnetic property. The transport properties of Cu-doped Sr₂Cu ₂CoO₂S₂ is affected by their magnetism.