Magnetic and electronic nature of layered manganese oxysulfide Sr ₂CuMnO ₃S

We have synthesized and investigated the magnetic and electronic nature of layered manganese oxysulfide Sr ₂CuMnO ₃S which crystallizes in an unusual intergrowth structure with Cu ₂S ₂ and pyramidal MnO ₅ layers separated by Sr ions. A Cu 2p x-ray photoemission spectroscopy (XPS) spectrum of Sr ₂CuMnO ₃S indicates that the Cu ion is in the monovalent state, or Cu ⁺. This feature of the Mn 2p XPS spectrum of Sr ₂CuMnO ₃S is similar to that of the parent compound La ³⁺Mn ³⁺O ₃ of colossal magnetoresistance materials. The MnO ₅ cluster model analysis suggests that the electronic nature of the pyramidal MnO ₅ layers belongs to a strongly correlated electron system, and the system is the so-called Mott insulator resulting from the strongly correlated electron nature. Magnetic susceptibility (χ) exhibits low-dimensional antiferromagnetic ordering of Mn ³⁺ in pyramidal MnO ₅ layers. Fitting the χ data to Curie-Weiss law provides evidence of strong second neighbor Mn-Mn interaction.