Abstract:We have developed a spintronic theory for the magnetic tunnel junction with single-crystal barrier. The theory is founded on optical theory and Patterson function approach. Therefore, the theory can adequately take into account the influences of the periodicity of the barrier and the lattice distortion. According to the theory, we have investigated the temperature characteristics of the tunnel magneto-Seebeck effect in MgO-based magnetic tunnel junctions. In the low temperature approximation, the temperature only has influence on the Seebeck coefficients through Fermi distribution function. However, in the present theory, the temperature can modify the potential parameter of barrier through lattice distortion, and further alters the Seebeck coefficients. Since the tunneling electrons will be scattered by the single-crystal barrier, the corresponding coherence will lead to the oscillation of the Seebeck coefficients. The above results can theoretically interpret the non-monotonic temperature characteristics of the Seebeck coefficient in the parallel configuration and TMS in MgO-based magnetic tunnel junctions. Furthermore, the physical mechanism of the non-monotonic temperature characteristics is clarified. In addition, we have investigated the influences of the parameters of the lattice distortion, e.g. strain, defect concentration and recovery temperature, on the temperature characteristics of the tunnel magneto-Seebeck effect. It is found that, the amplitudes of the non-monotonic variations of the Seebeck coefficient in the parallel configuration can be modulated by the defect concentration and the recovery temperature.
