Magnetic and Magnetotransport Properties of La0.7Sr0.2Ca0.1MnO3 Prepared From Nanoparticles.

We have studied magnetic and magnetotransport properties of a polycrystalline ceramics of La0.7Sr0.2Ca0.1MnO3 (LSCM) prepared from nanoparticles. The Curie temperature (TC) of the sample is about 340 K. Basing on the magnetic-field dependences of magnetization measured around TC, maximum magnetic-entropy changes under the applied fields of 10, 20 and 30 kOe are about 1.73, 2.74, 3.52 J/kg.K, respectively, which are higher than those reported on a parent compound of La0.7Sr0.3MnO3. To understand magnetic-interaction mechanisms taking place in the system, the critical behavior has been taken into account. By using the modified Arrott plot method, \beta and \gamma values associated with the spontaneous magnetization (Ms) and inverse initial susceptibility (\chi0^{-1}) have been obtained to be 0.472 \pm 0.016 and 1.061 \pm 0.024, respectively. These critical parameters are close to those expected for the mean-field theory (with \beta=0.5, and \gamma=1.0). A small deviation in value between our results and those expected for the mean-field theory could be due to an inhomogeneity in magnetism and/or interaction competitions between antiferromagnetic pairs (Mn^3+-Mn^3+ and Mn^4+-Mn^4+) and a ferromagnetic pair of Mn^3+-Mn^4+ in LSCM. Interestingly, in the temperature range of 180–300 K, magnetoresistance values keep quite stable at about 16 and 27% for the magnetic fields of 1 and 7 kOe, respectively. This makes LSCM more suitable to applications of magnetic sensitive sensors and reading heads working in a large temperature range. [ABSTRACT FROM PUBLISHER]