Magnetic Recording Medium With 30 GHz Resonance

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Solution Overview

Problem

The challenge in magnetic recording media is to increase recording density while maintaining thermal stability and easy writing properties, known as the trilemma, which is difficult to achieve due to the degradation of thermal stability with miniaturized ferromagnetic powder and the requirement for high coercive force.

Innovation Solution

A coating-type magnetic recording medium with a magnetic layer containing ferromagnetic powder and a binder on a non-magnetic support, exhibiting an intrinsic ferromagnetic resonance frequency of 30.0 GHz or more, enabling microwave assisted recording and improved thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If ferromagnetic powder particles are miniaturized to increase recording density, then recording density increases, but thermal stability of magnetization degrades

Engineering Contradiction:

Improverecording densityVSAvoidthermal stability of magnetization

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies parameter changes by adjusting the intrinsic ferromagnetic resonance frequency to 30.0 GHz or more through material composition optimization and particle size control. This parameter adjustment allows miniaturized particles to maintain sufficient thermal stability (KuV/kT ratio) while enabling increased recording density, thus resolving the contradiction between particle miniaturization and thermal stability maintenance.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If ferromagnetic powder with high anisotropic constant Ku is used to increase magnetic energy, then thermal stability improves, but coercive force increases and easy writing property degrades

Engineering Contradiction:

Improvethermal stability of magnetizationVSAvoideasy writing property

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent utilizes parameter changes by optimizing the intrinsic ferromagnetic resonance frequency to 30.0 GHz or more, which corresponds to specific ranges of anisotropic constant Ku and particle volume V. This optimized parameter set achieves a balance where thermal stability is improved through sufficient magnetic energy while coercive force remains at manageable levels, preserving easy writing properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies dynamics by introducing microwave magnetic fields during the recording process. The microwave fields dynamically assist magnetization inversion in particles with high Ku values, enabling writing operations without requiring excessively high coercive forces. This dynamic assistance resolves the contradiction between high thermal stability and easy writing.

Inventive Principle:

Principle #15Dynamics

3Reliability

If ferromagnetic powder with high coercive force is used to improve thermal stability, then record-holding property improves, but strong external magnetic field is required and easy writing degrades

Engineering Contradiction:

Improverecord-holding propertyVSAvoidexternal magnetic field strength

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent applies dynamics by using time-varying microwave magnetic fields during recording. These dynamic microwave fields provide assistance during magnetization inversion, enabling particles with high coercive force to be written without requiring proportionally high external magnetic fields. This resolves the contradiction between record-holding property and required external field strength.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent utilizes periodic action through microwave oscillations at frequencies of 30.0 GHz or more. The periodic microwave magnetic fields resonate with the ferromagnetic particles, providing cumulative assistance during magnetization switching. This periodic assistance enables high record-holding properties while reducing the peak external magnetic field requirements.

Inventive Principle:

Principle #19Periodic 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 solution allows for high-capacity data storage with increased recording density and thermal stability, enabling effective microwave assisted recording by utilizing ferromagnetic powder with high coercive force and appropriate particle sizes, and allows for multiplex recording on a single layer.

Implementation Method 1

the magnetic layer exhibits an intrinsic ferromagnetic resonance frequency of 30.0 GHz or more

Methodology Applied

Scientific EffectFerromagnetic resonance: Resonance

Implementation Method 2

enabling microwave assisted recording by utilizing ferromagnetic powder with high coercive force

Methodology Applied

Scientific EffectMicrowave assisted recording: Electromagnetic Induction

Data Source

PatentUS10115425B2Magnetic recording medium for microwave assisted recording and magnetic recording device

Publication Date: 2018.10.30 FUJIFILM CORP

AI summary

Provided is a coating-type magnetic recording medium for microwave assisted recording. A magnetic recording medium for microwave assisted recording having a magnetic layer including ferromagnetic powder and a binder on a non-magnetic support, in which the magnetic layer exhibits an intrinsic ferromagnetic resonance frequency of 30.0 GHz or more. A magnetic recording device including the magnetic recording medium and a magnetic head for microwave assisted recording.