title: Intergranular magnetoresistance in Sr2FeMoO6 from a magnetic tunnel barrier mechanism across grain boundaries.
abstract: We present magnetization (M) and magnetoresistance (MR) data for a series of Sr2FeMoO6 samples with independent control on antisite defect and grain-boundary densities, which reveal several unexpected features, including a novel switching-like behavior of MR with M. These, in conjunction with model calculations, establish that the MR in Sr2FeMoO6 is dominantly controlled by a new mechanism, derived from the magnetic polarization of grain-boundary regions acting like spin valves, leading to behavior qualitatively different from that usually encountered in tunneling MR. We show that a simple and useful experimental signature for the presence of this spin-valve-type MR (SVMR) is a wider hysteresis in MR compared to that in M.
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: D D
authors.initials: DD
authors.lastname: Sarma
authors.forename: Sugata
authors.initials: S
authors.lastname: Ray
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: A
authors.initials: A
authors.lastname: Fujimori
authors.forename: P
authors.initials: P
authors.lastname: Sanyal
authors.forename: H R
authors.initials: HR
authors.lastname: Krishnamurthy
authors.forename: C
authors.initials: C
authors.lastname: Dasgupta