Large room-temperature magnetoresistance in epitaxial La_0.7Ca_0.25Sr_0.05MnO₃ thin films prepared by sol–gel method

Abstract

Epitaxial La_0.7Ca_0.25Sr_0.05MnO₃ (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.

Graphical Abstract

The conventional sol–gel method produces the lanthanum manganese oxide thin films with excellent epitaxial structure and giant magnetoresistance at room temperature which can be used for either fundamental studies or real applications.