Ca doping effect on the magnetic and electronic transport properties in double perovskite PrBaCo₂O_5+δ films

Ca doped double perovskite PrBa_1-xCa_xCo₂O_5+δ (x = 0, 0.3, and 0.5) thin films were epitaxially grown on the (001) SrTiO₃ substrates to systematically investigate the A′ site doping effect on the magnetic and electronic transport properties. With the increase in the Ca content, the magnetization measurements on the films show that the magnetic moments are significantly increased and the largest magnetic moment of 88 emu/cm³ can be achieved in the film with x = 0.5 or about 90 times larger than that from the undoped PrBaCo₂O_5+δ film. The electronic transport property measurements on the films indicate that the electrical conductivity can be altered by various Ca doping contents. It is interesting to note that both undoped PrBaCo₂O_5+δ and PrBa_0.5Ca_0.5Co₂O_5+δ films exhibit simple activation behavior, but the PrBa_0.7Ca_0.3Co₂O_5+δ film exhibits the 3D variable-range hopping mode conduction.