Large room-temperature magnetoresistance in epitaxial La0.7Ca0.25Sr0.05MnO3 thin films prepared by sol–gel method
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Epitaxial La0.7Ca0.25Sr0.05MnO3 (LCSMO) thin films were successfully prepared on LaAlO3 (LAO) substrates by ordinary aqueous sol–gel method. X-ray diffraction result shows that the films have perfect crystalline orientation. The HRTEM results confirm that the films have epitaxial structure and the interface is very sharp and no misfit dislocations. The selected area electron diffraction patterns and fast Fourier transformation patterns mean that there exist three domains in the thin film. The single-particle spin-flip excitations are dominant for the metallic ferromagnets in low-temperature range. In paramagnetic range, the temperature dependence of resistivity can be well analyzed using a small polaron theory. The magnetoresistance value for the films reaches maximum about 65 % with 7 T magnetic field at 285 K which is promising for highly demanding applications. The conventional sol–gel method produces the lanthanum manganese oxide thin films with excellent epitaxial structure and large magnetoresistance at room temperature which can be used for either fundamental studies or real applications.
KeywordsSol–gel La0.7Ca0.25Sr0.05MnO3 Epitaxial growth Magnetic properties Magnetoresistance
The work was supported by National Natural Science Foundation of China (Grant Nos. 51302084, 11104074, 61574058, 61176011, 61376129, 11374098 and 11304097), Natural Science Foundation of Shanghai (Nos. 13ZR1412200), Key Laboratory of Inorganic function material and device, Chinese Academy of Sciences (KLIFMD-2011-06, KLIFMD-2012-01) and Fundamental Research Funds for the Central Universities (ECNU) and Key Laboratory of Polar Materials and Devices, Ministry of Education.