Antisite defects versus grain boundary competition in the tunneling magnetoresistance of the Sr2FeMoO6 double perovskite

D. NIEBIESKIKWIAT; F. PRADO; A. CANEIRO; R. D. SÁNCHEZ

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2004 vol. 70 p. 324121 - 324124

1098-0121

We present magnetic and transport measurements on the Sr2FeMoO6 double perovskite, and study thetunneling magnetoresistance (TMR) response when the amount of Fe/Mo disorder (antisite defects) and thegrain boundary (GB) properties are changed. We prepared two samples with different amounts of disorder(saturation magnetization MS<3.0 and 1.6mB, respectively) and performed several GB oxidation treatments.While MS remained unchanged, the resistivity srd was increased by more than five orders of magnitude afteroxidation and the TMR showed an appreciable increase, regardless of the amount of Fe/Mo disorder. At lowr values, the more disordered sample sMS<1.6mBd shows a diminished TMR due to a reduced electron spinpolarization. On the contrary, when the GBs dominate in the transport properties the effect of the disorder iswashed away and both samples exhibit the same improved TMR values.