Quantum oscillation of magnetoresistance in tunneling junctions with a nonmagnetic spacer

TL;DR

This paper presents a theoretical analysis of quantum oscillations in tunneling magnetoresistance caused by spacer layer thickness, emphasizing the roles of momentum selection, quantum well states, and disorder in explaining experimental observations.

Contribution

It introduces a theoretical model that explains the quantum oscillations in TMR with a nonmagnetic spacer, highlighting the importance of barrier-induced momentum selection and quantum well states.

Findings

Quantum oscillations depend on spacer thickness.

Disorder-induced diffusive scattering influences oscillation behavior.

The model explains the observed oscillation period and asymptotic TMR value.

Abstract

We make a theoretical study of the quantum oscillations of the tunneling magnetoresistance (TMR) as a function of the spacer layer thickness. Such oscillations were recently observed in tunneling junctions with a nonmagnetic metallic spacer at the barrier-electrode interface. It is shown that momentum selection due to the insulating barrier and conduction via quantum well states in the spacer, mediated by diffusive scattering caused by disorder, are essential features required to explain the observed period of oscillation in the TMR ratio and its asymptotic value for thick nonmagnetic spacer.