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 magneto resistive properties of La1-xCaxMnO3 (x approximate to 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(O) - R(H)] /R(H) in the field H = 5 T is about approximate to 2680%) is found near the Curie temperature (216K). 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. (C) 2004 Elsevier B.V. All rights reserved.