Charge pumping in magnetic tunnel junctions: Scattering theory

TL;DR

This paper presents a theoretical study of charge pumping in magnetic tunnel junctions, predicting measurable voltages under resonance conditions and quantum size effects based on magnetization dynamics and barrier parameters.

Contribution

It introduces a scattering theory approach to analyze charge pumping in FIF and FNIF magnetic tunnel junctions, highlighting new effects related to magnetization orientation and quantum size.

Findings

Measurable DC pumping voltage predicted at ferromagnetic resonance.

Large AC voltage expected at right-angle magnetizations.

Quantum size effects observed as a function of normal layer thickness.

Abstract

We study theoretically the charge transport pumped by magnetization dynamics through epitaxial FIF and FNIF magnetic tunnel junctions (F: Ferromagnet, I: Insulator, N: Normal metal). We predict a small but measurable DC pumping voltage under ferromagnetic resonance conditions for collinear magnetization configurations, which may change sign as function of barrier parameters. A much larger AC pumping voltage is expected when the magnetizations are at right angles. Quantum size effects are predicted for an FNIF structure as a function of the normal layer thickness.