Coherent transport in high performance double-spacer magnetic junctions

Abstract Spin-resonant tunneling mediated by quantized interlayer states has been studied using the tight-binding model for a composite magnetic junction with a thin non-magnetic metallic spacer, coherently inserted between the tunnel barrier and one of the ferromagnetic electrodes (F/I/N/F). An explicit analytical formula for the quantum transmission coefficient is derived and used for calculation of tunnel magnetoresistance (TMR) ratio in the Landauer formalism. The existence of strong magnetoresistance peaks is shown either at varying the on-site atomic energy and the width (number of atomic planes) of the N-spacer. The strongest TMR enhancement in the shallow band regime suggests a search for new spacer materials to optimize the device performance.