Magnetic Head Spin Torque Control Element Oxidation Detection

Solution Overview

Problem

The challenge in magnetic recording/reproducing devices is accurately detecting oxidation degradation of spin torque control elements due to variations in resistance values caused by disorderly residual magnetization, which complicates the detection of oxidation degradation under high-temperature conditions.

Innovation Solution

The magnetic head design incorporates a spin torque control element with a magnetization control layer and nonmagnetic conducting layers, where the material and thickness of these layers are optimized to minimize the absolute value of resistance differences and magnetoresistance effects, ensuring accurate detection of oxidation degradation by suppressing resistance variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the spin torque control element is used for write operations, then magnetic recording performance is improved, but resistance value varies due to magnetoresistance effect making oxidation degradation detection difficult

Engineering Contradiction:

Improveoxidation degradation detection accuracyVSAvoidresistance value stability

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by performing a magnetization reversal operation before measuring the resistance value. This preliminary step ensures that the magnetization of the spin torque control element is in a known state (aligned with the auxiliary magnetic pole), thereby eliminating the magnetoresistance effect that would otherwise cause measurement errors. This allows accurate detection of oxidation degradation by ensuring that resistance variations are due to oxidation rather than magnetization state.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the spin torque control element undergoes long-time dive under high temperature, then oxidation degradation occurs, but resistance variation due to residual magnetization masks the degradation signal

Engineering Contradiction:

Improveelement durability monitoringVSAvoidoxidation degradation detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies preliminary action by performing a magnetization reversal operation before measuring the resistance value. This preliminary step ensures that the magnetization of the spin torque control element is in a known state (aligned with the auxiliary magnetic pole), thereby eliminating the magnetoresistance effect that would otherwise cause measurement errors. This allows accurate detection of oxidation degradation by ensuring that resistance variations are due to oxidation rather than magnetization state.

Inventive Principle:

Principle #10Preliminary action

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

This design allows for precise detection of oxidation degradation with high accuracy by maintaining the absolute value of resistance differences and magnetoresistance effects within specific limits, enhancing the reliability of the magnetic head under high-temperature conditions.

Implementation Method 1

the resistance value varies due to the magnetoresistance effect

Methodology Applied

Scientific EffectMagnetoresistance effect: Magnetoresistance

Implementation Method 2

a spin torque control element which is a current-perpendicular-to-plane type giant magneto-resistance element or a current-perpendicular-to-plane type tunnel magneto-resistance element

Methodology Applied

Scientific EffectSpin torque:

Data Source

PatentUS11817135B2Magnetic head and magnetic recording/reproducing device

Publication Date: 2023.11.14 KK TOSHIBA

AI summary

According to one embodiment, a magnetic head includes a main pole, an auxiliary magnetic pole provided with a write gap in the main pole, a spin torque control element provided in the write gap, a bias current control portion which supplies a bias current to the spin torque control element, and a resistance measuring portion which measures a resistance value of the spin torque control element. The absolute value of a difference between a first resistance value when a bias current is applied with a polarity that magnetization of the spin torque control element is reversed and a second resistance value when the bias current is applied to a reversed polarity of the polarity is less than or equal to 4%.