Spin Torque Oscillation Element for High-Density Magnetic Recording

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Solution Overview

Problem

The challenge of achieving high recording density in magnetic recording is hindered by thermal fluctuations, which limit the efficiency of high-frequency assisted magnetic recording methods, particularly in efficiently applying high-frequency magnetic fields in high-density recording.

Innovation Solution

A magnetic recording head with a spin torque oscillation element comprising a first and second oscillation layer, a nonmagnetic spin sink layer, and a nonmagnetic intermediate layer, where the spin sink layer absorbs spin torque, allowing for improved torque transfer efficiency and generation of a high-frequency magnetic field, enabling efficient high-frequency assisted magnetic recording.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-frequency assisted magnetic recording method is used to achieve high recording density, then recording density can be increased beyond thermal fluctuation limits, but it becomes difficult to efficiently apply the high-frequency magnetic field in high-density recording

Engineering Contradiction:

Improverecording densityVSAvoidefficiency of applying high-frequency magnetic field

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent replaces the conventional mechanical/coil-based high-frequency magnetic field generation system with a spin torque oscillation element that utilizes spin transfer torque to generate high-frequency magnetic fields. This substitution enables efficient high-frequency field application at the nanoscale required for high-density recording by leveraging quantum mechanical spin effects rather than classical electromagnetic induction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters of the magnetic recording system by introducing spin torque oscillation elements that operate at specific resonant frequencies of the magnetic recording medium. By tuning the oscillation frequency to match the medium's resonant frequency, the system achieves enhanced coercivity reduction and improved recording efficiency at high densities

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If perpendicular magnetic recording is used to increase recording density, then recording density can be increased compared to longitudinal recording, but thermal fluctuation problems reappear at very high densities

Engineering Contradiction:

Improverecording densityVSAvoidthermal fluctuation stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies periodic high-frequency magnetic field oscillation to the magnetic recording medium during the writing process. This periodic action resonates with the magnetic moments in the medium, creating a time-varying assist field that periodically reduces coercivity and enables stable magnetization switching even in high-anisotropy perpendicular recording media, thereby overcoming thermal fluctuation limitations

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent utilizes magnetic resonance vibration by applying high-frequency magnetic fields that match the natural resonant frequency of the magnetic recording medium. This vibrational approach creates dynamic assistance during recording, allowing the system to achieve and maintain high recording densities while preserving signal stability against thermal effects

Inventive Principle:

Principle #18Mechanical vibration

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 enables reliable high-density magnetic recording by reducing the critical current density and maintaining high-frequency magnetic field strength, facilitating recording densities beyond 1 Tbits/inch² while minimizing thermal fluctuation impacts.

Implementation Method 1

a spin torque oscillation element provided between the main magnetic pole and the write-shield

Methodology Applied

Scientific EffectSpin torque oscillation:

Implementation Method 2

The nonmagnetic spin sink layer contains at least one element selected from the group consisting of Ru, Rh, Ta, W, Cr, Ir, Mo, Re, Nb, Pt, and Pd

Methodology Applied

Scientific EffectSpin torque absorption:

Data Source

PatentUS8605391B2Magnetic head and magnetic recording and reproducing device

Publication Date: 2013.12.10 KK TOSHIBA

AI summary

According to one embodiment, a magnetic head has a main magnetic pole, a write-shield constituting the main magnetic pole and a magnetic circuit, and a spin torque oscillation element provided between the main magnetic pole and the write-shield. The spin torque oscillation element is provided with a first oscillation layer, a nonmagnetic spin sink layer, a second oscillation layer, a nonmagnetic intermediate layer, and a spin injection layer provided in sequence from the write-shield side to the main magnetic pole side. The nonmagnetic spin sink layer is formed of at least one element selected from the group consisting of Ru, Rh, Ta, W, Cr, Ir, Mo, Re, Nb, Pt, and Pd.