Oxygen-induced grain boundary effects on magnetotransport properties of Sr2FeMoO6+d

D. NIEBIESKIKWIAT; A. CANEIRO; R. D. SANCHEZ; J. FONTCUBERTA

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

APS

Lugar: NY; Año: 2001 vol. 64 p. 18040601 - 18040604

0163-1829

The magnetic, electric, and structural properties of polycrystalline samples of Sr2FeMoO61 d with controlled oxygen content have been investigated for nominal values d50 and 0.04. We found that the magnetization and lattice parameters are the same in both samples, while the electric properties are drastically affected. This behavior shows that the difference in the oxygen contents is localized in a region near the surface of the grains, thus changing the transport properties of the grain boundaries ~gb?s!. The sample with d50.04 presents a resistivity ( r) that exceeds in more than two orders of magnitude the r for d50. Also the low-field magnetoresistance is enhanced in ´40% for d50.04 and the voltage-current characteristics present appreciable nonlinearities. We discuss these results in terms of a reinforced tunneling barrier due to the formation of an impurity phase at the gb?s.