Band edge noise spectroscopy of a magnetic tunnel junction

TL;DR

This paper introduces a novel noise spectroscopy method to probe the electronic band edges at buried magnetic tunnel junction interfaces, revealing insights into spin mixing and electronic structure.

Contribution

It presents a new approach using bias-dependent low frequency noise to analyze electron band edges and spin mixing in magnetic tunnel junctions.

Findings

Noise anomalies at specific voltages indicate band edge tunneling.

Magnetic state influences the magnitude of noise anomalies.

Results align qualitatively with numerical models.

Abstract

We propose a conceptually new way to gather information on the electron bands of buried metal(semiconductor)/insulator interfaces. The bias dependence of low frequency noise in Fe$_{1-x}$V$_{x}$/MgO/Fe (0 $<$ x $<$ 0.25) tunnel junctions show clear anomalies at specific applied voltages, reflecting electron tunneling to the band edges of the magnetic electrodes. The change in magnitude of these noise anomalies with the magnetic state allows evaluating the degree of spin mixing between the spin polarized bands at the ferromagnet/insulator interface. Our results are in qualitative agreement with numerical calculations.