Role of intergrowths in the properties of the naturally layered manganites

The structural and magnetic properties of the two-layered Ruddlesden–Popper phase SrO(La1−xSrxMnO3)2 with x=0.3 and x=0.4 are investigated. These naturally layered manganites exhibit a colossal magnetoresistance, a magnetic anisotropy which is strongly composition-dependent, almost no remanence, and a non-vanishing magnetization in a extended temperature range above the Curie temperature (TC). The magnetization in this temperature range is not intrinsic to the crystal, but is attributed to intergrowths. These two-dimensional (2D) lattice imperfections consist of additional or missing SrO layers and have been observed in transmission electron micrographs. The magnetic properties of the intergrowths differ from the bulk crystal which results in unusual magnetic behavior.