Recessed Spin Torque Oscillator for Stable High-Frequency Assist Recording

Solution Overview

Problem

In magnetic heads with a spin torque oscillator for high-frequency assist recording, the non-uniform magnetic field in the write gap leads to unstable magnetization on the air bearing surface, hindering the oscillation of the spin torque oscillator and degrading its oscillation characteristics, especially at shorter write gap lengths.

Innovation Solution

The spin injection layer and oscillation layer of the spin torque oscillator are recessed away from the air bearing surface, creating a recessed interval that maintains uniform magnetization and enhances oscillation, even at shorter write gap lengths, by adjusting the depth of the recess to optimize the gap magnetic field dispersion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the write gap length is reduced to increase recording density, then the gap magnetic field becomes stronger and recording density increases, but the magnetization uniformity in the write gap deteriorates causing unstable oscillation of the spin torque oscillator

Engineering Contradiction:

Improverecording densityVSAvoidmagnetization uniformity

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The spin torque oscillator is positioned at a specific location within the write gap where the magnetic field provides optimal magnetization uniformity. By selecting a particular depth position for the STO, the invention achieves stable oscillation characteristics while maintaining the short write gap structure needed for high recording density.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention addresses the magnetization uniformity issue by transitioning from a two-dimensional planar arrangement to a three-dimensional configuration. The spin torque oscillator is placed at a specific depth position within the write gap, utilizing the vertical dimension to achieve optimal magnetic field conditions for stable oscillation while maintaining short write gap length for high recording density.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the write gap length is reduced to achieve higher recording density, then the gap magnetic field intensity increases, but the oscillation characteristics of the spin torque oscillator degrade due to non-uniform magnetic field

Engineering Contradiction:

Improverecording densityVSAvoidoscillation characteristics

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The spin torque oscillator is positioned at a specific location within the write gap where the magnetic field provides optimal magnetization uniformity. By selecting a particular depth position for the STO, the invention achieves stable oscillation characteristics while maintaining the short write gap structure needed for high recording density.

Inventive Principle:

Principle #3Local quality

3Device complexity

If the spin torque oscillator is placed near the air bearing surface to simplify structure, then the device complexity is reduced, but the magnetization becomes unstable due to stronger gap magnetic field causing poor oscillation performance

Engineering Contradiction:

Improvestructure simplicityVSAvoidmagnetization stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The invention addresses the magnetization uniformity issue by transitioning from a two-dimensional planar arrangement to a three-dimensional configuration. The spin torque oscillator is placed at a specific depth position within the write gap, utilizing the vertical dimension to achieve optimal magnetic field conditions for stable oscillation while maintaining short write gap length for high recording density.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 configuration allows the spin torque oscillator to maintain excellent oscillation characteristics and apply a strong high-frequency magnetic field, enabling stable high-frequency assist recording and higher recording density, even with write gaps as short as 30 nm or less.

Implementation Method 1

a high-frequency assist element, for example, a spin torque oscillator, is provided in the write gap between the write shield magnetic pole and the main pole, and a high-frequency magnetic field is applied to the magnetic recording layer of a magnetic disk by the spin torque oscillator

Methodology Applied

Scientific EffectSpin torque oscillator:

Implementation Method 2

the recording head comprises a main pole configured to produce a perpendicular magnetic field

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentUS9792933B2Magnetic head, disk drive with the same and method of manufacturing magnetic head

Publication Date: 2017.10.17 KK TOSHIBA

AI summary

According to one embodiment, a magnetic head includes an air bearing surface, a first surface on which contact pads connected to elements are provided, a pair of second surfaces provided respectively with a connection terminal connected to the contact pad, a main pole with a distal end portion extending to the air bearing surface, a write shield opposing the distal end portion of the main pole with a write gap therebetween, and a high-frequency oscillator provided between the main pole and the write shield within the write gap and electrically connected to the main pole and the write shield. The high-frequency oscillator includes a spin injection layer and an oscillation layer, and at least the oscillation layer is recessed in a direction away from the air bearing surface.