Voltage dependence of giant tunnel magnetoresistance in triple barrier magnetic systems

Abstract

A quantum theory of the dependence on bias voltage of the tunnel magnetoresistance in a triple barrier system of the form MOMOMOM is presented. The Ms represent magnetic metallic layers and the Os are thin tunnel barriers. The two inner layers form spin-dependent quantum wells. The relative orientation of the magnetization in the successive magnetic layers can be changed from parallel to antiparallel. For a particular thickness of the inner metallic layers, a very large change of resistance occurs between the parallel and antiparallel magnetic configurations due to the spin dependence of the resonant tunnelling in these layers. It is shown that oscillations in the voltage dependence of the magnetoresistance amplitude take place associated with oscillations between resonant and antiresonant tunnelling as a function of the electrons' energy.