Strain relaxation and transport properties of epitaxial Pr_(0.5)Ba_(0.5)MnO_(3-δ) thin films

摘要

Highly epitaxial Pr0.5Ba0.5MnO3-δ(PBMO) thin films were fabricated on (001) LaAlO3substrates with various growth temperatures by using pulsed laser deposition system. Confirmed by x-ray diffraction and transmission electron microscopy, all the films arec-axis orientation and the strain induced by the lattice misfit is fully relaxed by the form of dislocations. By increasing the growth temperature, the film qualities and oxygen vacancies increase. The transport properties of the films follow variable range hopping and only depend on the film quality. However, the magnetic properties are related to the competition between the film quality and the oxygen content in it. The film quality dominated the magnetic properties of the film grown at 560 °C, since the largest tilt of the crystalline plane leads to the antiferromagnetic takes charge of the magnetic properties. The quality of the film grown at 720 °C is the best, but the relatively small oxygen content in it make its magnetic moment lower than that grown at 640 °C. The film grown at 640 °C with the optimal crystal quality and oxygen content exhibits the maximum magnetic moment. These phenomena indicate that the physical properties of PBMO thin film are highly dependent on its microstructure, and a desired property can be achieved by tuning its growth temperature.