Spin-torque Dynamics for Noise Reduction in Vortex-based Sensors

TL;DR

This paper investigates how spin-transfer dynamics in vortex-based TMR sensors can reduce 1/f low-frequency noise, improving sensor performance by leveraging vortex core motion to minimize defect pinning effects.

Contribution

It demonstrates that activating vortex core dynamics significantly decreases 1/f noise, offering a novel method to enhance vortex-based magnetic sensor performance.

Findings

Vortex state exhibits higher noise than uniform states.

Spin-transfer induced vortex dynamics reduce 1/f noise.

Non-resonant RF or current further decreases noise.

Abstract

Performance of magnetoresistive sensors is today mainly limited by their 1/f low-frequency noise. Here, we study this noise component in vortex-based TMR sensors. We compare the noise level in different magnetization configurations of the device, i.e vortex state or uniform parallel or antiparallel states. We find that the vortex state is at least an order of magnitude noisier than the uniform states. Nevertheless, by activating the spin-transfer induced dynamics of the vortex configuration, we observe a reduction of the 1/f noise, close to the values measured in the AP state, as the vortex core has a lower probability of pinning into defect sites. Additionally, by driving the dynamics of the vortex core by a non-resonant rf field or current we demonstrate that the 1/f noise can be further decreased. The ability to reduce the 1/f low-frequency noise in vortex-based devices by leveraging their spin-transfer dynamics thus enhances their applicability in the magnetic sensors' landscape.