Voltage and temperature dependence of the grain boundary tunneling magnetoresistance in manganites
II. Physikalisches Institut, Universität zu Köln
Zülpicher Str. 77, D-50937 Köln, Germany
Corresponding author: email@example.com
Accepted: 21 March 2000
We have performed a systematic analysis of the voltage and temperature dependence of the tunneling magnetoresistance (TMR) of grain boundaries (GB) in the manganites. We find a strong decrease of the TMR with increasing voltage and temperature. The decrease of the TMR with increasing voltage scales with an increase of the inelastic tunneling current due to multi-step inelastic tunneling via localized defect states in the tunneling barrier. This behavior can be described within a three-current model for magnetic tunnel junctions that extends the two-current Jullière model by adding an inelastic, spin-independent tunneling contribution. Our analysis gives strong evidence that the observed drastic decrease of the GB-TMR in manganites is caused by an imperfect tunneling barrier.
PACS: 75.70.Cn – Interfacial magnetic properties (multilayers, magnetic quantum wells, super lattices, magnetic heterostructures) / 75.70.Ak – Magnetic properties of monolayers and thin films / 73.40.-c – Electronic transport in interface structures
© EDP Sciences, 2000