Intrinsic and extrinsic magnetic properties of the naturally layered manganites

Structural and magnetic properties of the two-layered Ruddlesden-Popper pha se SrO(La1-xSrxMnO3)(2) with x=0.3-0.5 are highlighted. Intrinsic propertie s of these naturally layered manganites include a "colossal" magnetoresista nce, a composition-dependent magnetic anisotropy, and almost no remanence. Above the Curie temperature there is a nonvanishing extrinsic magnetization attributed to intergrowths (stacking faults in the layered structure). The se lattice imperfections consist of additional or missing manganite lagers, as observed in transmission electron microscopy. Their role in influencing the properties of the host material is highlighted. (C) 2000 American Vacu um Society, [S0734-2101(00)01404-4].