Sub-Poissonian shot noise in CoFeB/MgO/CoFeB-based magnetic tunneling junctions

TL;DR

This study investigates shot noise in magnetic tunneling junctions, revealing sub-Poissonian electron tunneling behavior in the parallel magnetic configuration due to spin-dependent coherent transport.

Contribution

It provides the first measurement of sub-Poissonian shot noise in CoFeB/MgO/CoFeB junctions, highlighting the role of spin-dependent coherence.

Findings

Fano factor close to 1 in anti-parallel configuration

Fano factor approximately 0.91 in parallel configuration

Evidence of sub-Poissonian tunneling due to spin coherence

Abstract

We measured the shot noise in the CoFeB/MgO/CoFeB-based magnetic tunneling junctions with a high tunneling magnetoresistance ratio (over 200% at 3 K). Although the Fano factor in the anti-parallel configuration is close to unity, it is observed to be typically 0.91\pm0.01 in the parallel configuration. It indicates the sub-Poissonian process of the electron tunneling in the parallel configuration due to the relevance of the spin-dependent coherent transport in the low bias regime.