Pressure effect on magnetic and electronic nature of Sr2Cu2CoO2S2 with strongly correlated CoO2 square-planes

We have studied pressure effects on the magnetic and electronic nature of layered oxysulfide Sr2Cu2CoO2S2 which crystallizes in an unusual intergrowth structure. The derivative permeability (<f>dμ/dT</f>) curves have a kink near <f>Tt</f> at which the antiferromagnetic nature is changed from 2D to 3D; <f>Tt</f> extremely rises with increasing pressure <f>(dTt/dP=13.5 K/kbar),</f> indicating that 3D antiferromagnetic state is more stable under pressure. The <f>Tt</f> in the <f>dμ/dT</f> curves correspond to the bending point of the resistivity, and above <f>Tt</f> the nearest-neighbor hopping conduction occurs. These features would be discussed from the viewpoint of the coupled nature of charge carriers and 2D antiferromagnetic spin ordering. [Copyright &y& Elsevier]