層状Mn酸化硫化物Sr_2CuMnO_3S及びSr_4Cu_2Mn_3O_<7.5>S_2における不純物置換効果

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We report the carrier-doping effects in layered manganese oxysulfides Sr_2CuMnO_3S and Sr_4Cu_2Mn_3O_<7.5>S_2 with a two-dimensional SrMnO_x perovskite-like layer. According to the Cu 2p core-level x-ray photoemission spectroscopy (XPS), Cu ions of Sr_2CuMn_<1-x>ZnO_3S and Sr_<4-x>La_xCu_2Mn_3O_<7.5>S_2 are Cu^<1+> and Cu^<1+>/Cu^<2+>, respectively. On the other hand, the Mn 2p XPS spectra indicate that the Mn ions are Mn^<3+> in mother compounds (Sr_4Cu_2Mn_30_<7.5>S_2 and Sr_2CuMnO_3S), and that they are Mn^<3+>/Mn^<4+> in Sr_2CuMn_<1-x>Zn_xO_3S. Sr_2CuMnO_3S exhibits low-dimensional antiferromagnetic ordering at 120K, while an increase tendency of magnetic susceptibility in cooling is observed below 50 K. The antiferromagnetic order of Sr_2CuMn_<1-x>Zn_xO_3S (x ≤ 0.2) is destroyed by an increase in non-magnetic Zn^<2+> ions, and the steepness of the increase tendency of magnetic susceptibility in cooling is also enhanced by increasing Zn^<2+> ions. It is supposed that ferromagnetic and antiferromagnetic magnetic order co-exist in Sr_2CuMn_<1-x>Zn_xO_3S. The La-doped samples Sr_<4-x>La_xCu_2Mn_3O_<7.5>S_2 (x≤0.2) show spin-glass-like behavior below 200 K. It is ascribed to the competition between the weak ferromagnetic double exchange interaction and the antiferromagnetic super-exchange interaction.
社団法人日本磁気学会の論文
2003-05-01