Large magnetoresistance values are obtained ontunnel junctions epitaxially deposited by pulsed4aser depositionand consisting of ferromagnetic manganiteLa_(0.67)Sr_(0.33)MnO_3 electrodes separated by varioustunnel barriers: SrTiO_3, PrBaCu_(2.8) Ga_(0.2)O_7 andCeO_2. The magnetoresistance can be decomposed into a low-field and a high-field contribution. The latter is attributed to thepresence of canted interfacial manganite phases, as confirmedby the temperature behaviour of the resistance. A low-fieldmagnetoresistance ratio of 450 percent below 100 Oe isobtained on a sample wit a SrTiO_3 barrier, indicating a spinpolarization value in excess of 0.83 for the manganite.
展开▼
