Magnetic Head Pole Laminated Structure for Spin Wave Energy Loss

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Solution Overview

Problem

Magnetic heads for perpendicular magnetic recording face challenges in achieving sufficient recording capability due to energy loss from spin waves in the main and return poles, which suppresses the intensity of the high-frequency magnetic field needed for magnetization reversal, making it difficult to achieve high recording density and capacity.

Innovation Solution

Incorporating a laminated structure portion with magnetic and nonmagnetic layers in at least one of the main or return poles facing the high-frequency oscillator, which reduces energy loss from spin waves and enhances the oscillation amplitude of the spin-torque oscillator, thereby increasing the intensity of the circularly polarized high-frequency magnetic field applied to the recording layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the main and return poles are formed of continuous magnetic film to enable perpendicular magnetic recording, then the recording head can produce the necessary magnetic field, but magnetization fluctuation occurs due to high-frequency magnetic field from spin-torque oscillator, causing spin waves and energy loss

Engineering Contradiction:

Improvemagnetic field production capabilityVSAvoidenergy loss from spin waves

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The continuous magnetic film of the main pole or return pole is divided into multiple magnetic layers separated by nonmagnetic layers, creating a laminated structure. This segmentation prevents the formation of spin waves by disrupting the continuous magnetization, thereby reducing energy loss while maintaining magnetic field production capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pole structure is transformed from a single continuous magnetic material into a composite laminated structure consisting of alternating magnetic layers and nonmagnetic layers. This composite structure combines the magnetic properties needed for field generation with the nonmagnetic properties that suppress spin wave formation and energy loss.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the distance between main and return poles is reduced to enlarge gap magnetic field for higher recording density, then recording density improves, but the poles are located near the spin-torque oscillator causing increased magnetization fluctuation and spin wave energy loss

Engineering Contradiction:

Improverecording densityVSAvoidenergy loss from spin waves

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

By segmenting the pole into laminated magnetic and nonmagnetic layers, the structure can be positioned close to the spin-torque oscillator for high recording density while the nonmagnetic layers prevent spin wave formation and associated energy losses that would otherwise occur at such close proximity.

Inventive Principle:

Principle #1Segmentation

3Reliability

If continuous magnetic film is used in main and return poles, then the magnetic path is closed effectively, but spin waves occur due to high-frequency magnetic field oscillation, suppressing spin-torque oscillator performance

Engineering Contradiction:

Improvemagnetic path closureVSAvoidenergy loss from spin waves

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The pole structure uses composite laminated materials where magnetic layers maintain the magnetic path closure for reliable flux conduction, while interspersed nonmagnetic layers suppress spin wave formation, thereby preserving both magnetic path effectiveness and spin-torque oscillator performance.

Inventive Principle:

Principle #40Composite materials

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 for improved recording capability and stable recording/reproducing properties by reducing energy loss and increasing the intensity of the high-frequency magnetic field, leading to enhanced recording signal quality.

Implementation Method 1

a spin-torque oscillator for use as a high-frequency oscillation element is disposed between main and return poles. A high-frequency magnetic field is applied from the spin-torque oscillator to a magnetic recording layer.

Methodology Applied

Scientific EffectSpin-torque oscillator:

Implementation Method 2

magnetization of the main and return poles fluctuates due to a high-frequency magnetic field produced as the spin-torque oscillator oscillates, whereupon spin waves occur in the main and return poles. An energy loss due to the spin waves increases

Methodology Applied

Scientific EffectSpin waves:

Data Source

PatentUS8755147B2Magnetic head pole including laminated structure having magnetic and nonmagnetic layers

Publication Date: 2014.06.17 KK TOSHIBA

AI summary

According to one embodiment, a magnetic head includes a main pole configured to apply a recording magnetic field to a recording layer of a recording medium, a return pole opposed to the main pole with a write gap therebetween, and a high-frequency oscillator between respective facing surfaces of the main pole and the return pole and configured to produce a high-frequency magnetic field. At least one of the main and return poles faces the high-frequency oscillator and includes a laminated structure portion includes a magnetic layer and a nonmagnetic layer laminated to one another.