Voltage dependence of giant tunnel magnetoresistance in triple barrier magnetic systems

A quantum theory of the dependence on bias voltage of the tunnel magnetores istance in a triple barrier system of the form MOMOMOM is presented. The Ms represent magnetic metallic layers and the Os are thin tunnel barriers. Th e two inner layers form spin-dependent quantum wells. The relative orientat ion of the magnetization in the successive magnetic layers can be changed f rom parallel to antiparallel. For a particular thickness of the inner metal lic layers, a very large change of resistance occurs between the parallel a nd antiparallel magnetic configurations due to the spin dependence of the r esonant tunnelling in these layers. It is shown that oscillations in the vo ltage dependence of the magnetoresistance amplitude take place associated w ith oscillations between resonant and antiresonant tunnelling as a function of the electrons' energy.