BiSb Spin Torque Oscillator Sensor for Magnetic Field Detection

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Solution Overview

Problem

Conventional spin torque oscillator (STO) devices based on spin-orbit torque (SOT) have limited precession/oscillation and lower signal output due to a low spin Hall angle, which affects their efficiency and reliability in magnetic recording applications.

Innovation Solution

A bismuth antimony (BiSb) based STO sensor is developed, incorporating a BiSb layer with a (012) orientation within a spin-orbit torque device and a magnetic tunnel junction (MTJ) structure, enhancing the spin Hall angle and efficiency by utilizing a larger spin Hall angle and high electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional SOT-based STO devices are used, then device reliability is improved, but signal output and dynamic frequency range are reduced due to low spin Hall angle

Engineering Contradiction:

Improvedevice reliabilityVSAvoidsignal output

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter (spin Hall angle) by replacing conventional SOT layers with topological insulator materials having inherently higher spin Hall angles, thereby improving signal output while maintaining the SOT device configuration and reliability benefits

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures combining topological insulator layers with magnetic tunnel junctions and buffer layers, creating a multi-layer composite that achieves both high spin Hall angle and device reliability

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If higher applied current is used in STT based STO devices, then signal/frequency output is improved, but device reliability deteriorates

Engineering Contradiction:

Improvesignal/frequency outputVSAvoiddevice reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent substitutes the spin-transfer torque mechanism with spin-orbit torque mechanism, replacing the need for high perpendicular current with an in-plane current flow through the SOT layer, thereby achieving signal output without compromising reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameter (current direction and magnitude) by utilizing in-plane current flow in the SOT layer instead of high perpendicular current, achieving the same magnetic layer oscillation with lower and safer current levels

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The BiSb based STO sensor achieves improved signal sensitivity and dynamic frequency range, with a spin Hall angle of 2, resulting in higher performance and reliability compared to conventional STO devices, allowing for better magnetic field detection and data reading.

Implementation Method 1

magnetic layer processing/oscillation is induced by an in-plane current that flows through the SOT layer by the spin Hall effect

Methodology Applied

Scientific EffectSpin Hall Effect: Hall Effect

Data Source

PatentUS20250014595A1Topological Insulator Based Spin Torque Oscillator Reader

Publication Date: 2025.01.09 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

The present disclosure generally relates to a bismuth antimony (BiSb) based STO (spin torque oscillator) sensor. The STO sensor comprises a SOT device and a magnetic tunnel junction (MTJ) structure. By utilizing a BiSb layer within the SOT device, a larger spin Hall angle (SHA) can be achieved, thereby improving the efficiency and reliability of the STO sensor.