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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 (dμ/dT) curves have a kink near Tt at which the antiferromagnetic nature is changed from 2D to 3D; Tt extremely rises with increasing pressure (dTt/dP=13.5 K/kbar), indicating that 3D antiferromagnetic state is more stable under pressure. The Tt in the dμ/dT curves correspond to the bending point of the resistivity, and above Tt 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]

We have studied the magnetic dilution and electronic nature of Zn doping on the Mn site in the colossal magnetoresistant material La0.7Pb0.3MnO3 (x≤0.3). Small non-magnetic Zn2+ doping tends to separate the system into ferromagnetic clusters to weaken the long-range ferromagnetic order and to reduce the Curie temperature. The spin polarizability of the x=0–0.3 samples is estimated to be 0.97–1.00, indicating that the x=0–0.3 samples are the spin polarized materials in which the conductivity is dominated by single-spin charge carriers. Small doping (x≥0.1) induces the metal–insulator transition and destroys the metallic state with long-range ferromagnetic order. [Copyright &y& Elsevier]