Ultra-sensitive nanoscale magnetic field sensors based on resonant spin filtering

TL;DR

This paper introduces nanoscale magnetic sensors based on resonant spin filtering, achieving ultra-high sensitivity and tunability through innovative multilayer magnetic tunnel junction designs.

Contribution

It presents a new design of magnetic tunnel junctions utilizing resonant spin filtering, significantly enhancing sensitivity and flexibility over traditional trilayer sensors.

Findings

Peak tunnel magneto resistance of approximately 2500% achieved.

Current sensitivity increased by over 300% compared to typical sensors.

Sensitivity can be further increased by 700% through angle-dependent spin filtering.

Abstract

Solid state magnetic field sensors based on magneto-resistance modulation find direct applications in communication devices, specifically in proximity detection, rotational reference detection and current sensing. In this work, we propose sensor structures based on the magneto-resistance physics of resonant spin-filtering and present device designs catered toward exceptional magnetic field sensing capabilities. Using the non-equilibrium Green's function spin transport formalism self consistently coupled to the Poisson's equation, we present highly-tunable pentalayer magnetic tunnel junction structures that are capable of exhibiting an ultra-high peak tunnel magneto resistance $(\approx 2500 \%$). We show how this translates to device designs featuring an ultra-high current sensitivity enhancement of over 300\% in comparison with typical trilayer MTJ sensors, and a wider tunable range of field sensitivity. We also demonstrate that a dynamic variation in sensor functionalities with the structural landscape enables a superior design flexibility over typical trilayer sensors. An optimal design exhibiting close to a 700\% sensitivity increase as a result of angle dependent spin filtering is then presented.This work sets a stage to engineer spintronic building blocks via the design of functional structures tailored to exhibit ultra-sensitive spin filtering.