Extrinsic inhomogeneity effects in magnetic, transport and magnetoresistive properties of La1-xCaxMnO3 (x≈0.33) crystal prepared by the floating-zone method

The magnetic, transport and magnetoresistive properties of La1-xCaxMnO3 (x≈0.33) crystals prepared by the floating-zone method are studied. In general, these properties testify to rather good crystal perfection of the sample studied. In particular, a huge magnetoresistance ([R(0)-R(H)]/R(H) in the field H=5T is about ≈2680%) is found near the Curie temperature (216 K). At the same time, some distinct features of measured properties indicate the influence of extrinsic inhomogeneities arising due to technological factors in the sample preparation. Analysis of the data obtained shows that these are rare grain boundaries and twins.