Role of A-site deficiency in the magneto-transport properties of Pr0.7Sr0.3MnO3 relaxed films

The magneto-transport properties of thick relaxed A-site deficient films having the composition Pr-0.6 square 0.1Sr0.3MnO3(P square SMO with the square symbol for the Pr vacancy) and Pr0.7Sr0.2 square 0.1MnO3(PS square MO) are studied. A direct comparison with a Pr0.7Sr0.3MnO3(PSMO) completely relaxed film, deposited under the same growth conditions, shows a reduction of the in-plane parameter a(100) associated to an enhancement of the out-plane parameter. The strains ( bulk strain epsilon(B) and biaxial Jahn- Teller strain epsilon(J-T)) do vary with the nature of the cationic vacancy. For example, an enhancement of epsilon(B) of 9% in the PS square MO film (Sr deficient) produces a decrease of T-C of 30 K, whereas the Pr deficient P square SMO film exhibits a large reduction of both epsilon(B)(- 16%) and epsilon(J-T) ( divided by a factor of 5), which enhances T-C of 12 K, similarly to previous observations on bulk ceramics. With a reduced resistivity (rho < 0.02 Omega cm), the obtained Pr-deficient film, P square SMO, exhibits the best magneto-transport properties with a decreasing magnetoresistance sensitivity at low field.