Magnetic properties of layered oxysulfide Sr[sub 2]Cu[sub 2](Co,Cu)O[sub 2]S[sub 2] with Cu-doped CoO[sub 2] square planes.

We have studied the magnetic properties of layered oxysulfide Sr[sub 2]Cu[sub 2](Co,Cu)O[sub 2]S[sub 2] with the (Co,Cu)O[sub 2] planes. Magnetic susceptibility shows a broad maximum indicative of two-dimensional antiferromagnetic nature above 140 K. Below 80 K, the divergence between zero-field cooled and field cooled magnetizations is seen; long time decay is observed at 10 and 75 K, while it is not observed at 45 K. These feature is discussed from the viewpoint of the strongly and frustrated spin system which is different from the traditional spin glass. [ABSTRACT FROM AUTHOR]