Asymmetric interfacial scattering effect on tunneling conductance of ferromagnet/superconductor/ferromagnet junctions

Abstract

The tunneling conductance spectra of a magnetic tunnel junction between ferromagnet/superconductor/ferromagnet material interfaces were theoretically studied using the scattering approach in a two dimensional system. As the main area of interest, the interfacial scattering at the two interfaces was modeled by Dirac delta potentials and set to be unequal in their values to verify which potential was more sensitive to the conductance spectra of the junctions. It was found that the conductance spectra in the region where the energy was less than the energy gap of the superconductor were sensitive to the potential strength at the first interface that is the incident side of an electron. When the electron was injected from different sides of the junctions, the conductance spectra of these two incident processes were different in magnitude in the case of asymmetric scattering potential. Particularly, the greater the different values of the two potential strengths, the larger the difference in the conductance spectra. This result can be used to identify the quality of a magnetic tunnel junction that is composed of a superconductor material. Moreover, the effect of the exchange energy and the superconducting thickness on the transport properties was analyzed.