Effects of temperature on the magnetic tunnel junctions with periodic grating barrier

Abstract

We have developed a tunneling theory to describe the temperature dependence of tunneling magnetoresistance (TMR) of the magnetic tunnel junctions (MTJs) with periodic grating barrier. Through the Patterson function approach, the theory can handle easily the influence of the lattice distortion of the barrier on the tunneling process of the electrons. The lattice distortion of the barrier is sensible to the temperature and can be quite easily weakened by the thermal relaxation of the strain, and thus the tunneling process of the electrons will be significantly altered with the variation of the temperature of the system. That is just the physical mechanism for the temperature dependence of the TMR. From it, we find two main results: 1. The decrease of TMR with rising temperature is mostly carried by a change in the antiparallel resistance (RAP), and the parallel resistance (RP) changes so little that it seems roughly constant, if compared to the RAP. 2. For the annealed MTJ, the RAP is significantly more sensitive to the strain than the RP, and for non-annealed MTJ, both the RP and RAP are not sensitive to the strain. They are both in agreement with the experiments of the MgO-based MTJs. Other relevant properties are also discussed.