The tunneling time in FM/I/SF/NM spin filter tunnel junctions

Abstract

Based on the free electronic model and the Winful’s tunneling time theory, the spin dependent dwell time and the phase time in ferromagnetic metal/nonferromagnetic metal/spin filter layer/normal metal single spin filter tunneling junctions (FM/I/SF/NM) are investigated. The results show that, different from the traditional FM/I/FM structures, the transmission coefficients for up and down spin electrons are not equal due to the effects of the SF layer when the molecular fields in FM and SF layers are at antiparallel arrangement. With the higher incident electronic energies (the incident energies are higher than the barrier height), as the decreasing influences of the self-interference delay, the phase times and the dwell times tend to same for different spin orientations electrons. But with the lower incident electronic energies (the incident energies are smaller than the barrier height), as the increasing influences of the self-interference delay, the differences between the phase times and the dwell times appear for different spin orientations electrons. And, the barrier heights of the I and SF layers, and the widths and the molecular fields of spin filter barrier can induce large differences between the phase times and the dwell times for spin-up electrons. But for the spin-down electrons, the differences between the phase times and the dwell times are induced mainly by the changes of parameters of the SF layer and tinily by the varies of barrier heights of the I layer.