Temperature dependence of resistance in epitaxial Fe/MgO/Fe magnetic tunnel junctions

摘要

The temperature dependence of resistance in parallel (P) and antiparallel (AP) configurations (R_(P,AP)) has been investigated in epitaxial Fe/MgO/Fe junctions with varying MgO barrier thicknesses t_(MgO). R_(AP) exhibits a substantial decrease with increasing temperature for samples with t_(MgO) ranging from 3.0 to 1.5 nm. In contrast, R_P is approximately temperature independent when t_(MgO) = 3.0 nm and increases with temperature when t_(MgO)=2.1 and 1.5 nm. Possible origins of this temperature dependence of resistance, which include taking into account a spin independent term and consideration of spin-flip scattering, are discussed. We attribute the temperature dependence of R_(P,AP) to the misalignment of magnetic moments in the electrodes due to thermal excitations and its effect on the spin dependent tunneling.