Magnetoresistance of ferromagnetic tunnel junctions in the double-exchange model
We conduct a theoretical study of the temperature dependence of the spin polarization ( P) and the magnetoresistance (MR) ratio using the double exchange (DE) model for ferromagnetic tunnel junctions with half-metallic systems. It is shown that the strong exchange coupling in the DE model plays an important role in the temperature dependence of both P and the MR ratio; their values can be less than the maximum values expected for half-metallic systems at low temperatures, and the MR ratio decreases more rapidly than P with increasing temperature. The calculated results, however, indicate that the MR ratio may still be large at high temperatures near the Curie temperature.
Itoh
H
Department of Quantum Engineering, Nagoya University, Nagoya 464-8603, Japan.
Ohsawa
T
Inoue
J