Magnetic stack, and related data storage devices, systems, and methods

Solution Overview

Problem

Existing data storage devices face challenges in increasing areal density capability (ADC) due to thermal instability and inhomogeneous field patterns in magnetic recording media, particularly in heat-assisted magnetic recording (HAMR) systems, which are costly to manufacture using bit-patterned media.

Innovation Solution

A magnetic recording layer comprising ferromagnetic, discrete regions within an antiferromagnetic matrix, formed via an 'on-disk' method, where discrete regions are converted from a continuous layer using methods like laser heating or electric field application, achieving thermal stability and high ADC without lithography.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If heat-assisted magnetic recording (HAMR) is used to increase areal density capability, then ADC is improved, but manufacturing cost increases and thermal instability occurs

Engineering Contradiction:

Improveareal density capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The magnetic recording layer is segmented into discrete ferromagnetic regions separated by antiferromagnetic material, creating bit-patterned media structures that enable high areal density without requiring complex lithography processes. This segmentation allows independent control of magnetic bits while simplifying manufacturing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the magnetic properties of the recording layer by using materials that undergo phase transitions or have temperature-dependent coercivity, allowing the media to be written at elevated temperatures and stabilized at operating temperatures, thereby achieving high ADC without expensive HAMR infrastructure.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If bit-patterned media is used to achieve high areal density, then ADC is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveareal density capabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The magnetic recording layer is segmented into discrete ferromagnetic regions separated by antiferromagnetic material, creating bit-patterned media structures that enable high areal density without requiring complex lithography processes. This segmentation allows independent control of magnetic bits while simplifying manufacturing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The antiferromagnetic material self-organizes into a matrix structure that automatically defines the positions of ferromagnetic regions, eliminating the need for external lithography patterning. The system self-patterns during deposition, reducing manufacturing complexity.

Inventive Principle:

Principle #25Self-service

3Productivity

If small magnetic regions are used to increase areal density, then ADC is improved, but thermal stability deteriorates

Engineering Contradiction:

Improveareal density capabilityVSAvoidthermal stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The invention uses a composite structure of ferromagnetic regions embedded in an antiferromagnetic matrix. The antiferromagnetic material provides thermal stability to the small ferromagnetic regions through exchange coupling, preventing superparamagnetic effects while maintaining high areal density.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the magnetic properties of the recording layer by using materials that undergo phase transitions or have temperature-dependent coercivity, allowing the media to be written at elevated temperatures and stabilized at operating temperatures, thereby achieving high ADC without expensive HAMR infrastructure.

Inventive Principle:

Principle #35Parameter changes

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

The solution provides improved areal density capability (ADC) and signal-to-noise ratio (SNR) by enabling small, thermally stable ferromagnetic regions, overcoming thermal instability and manufacturing costs of bit-patterned media.

Implementation Method 1

The discrete regions can be exchange-decoupled from one another and exchange-coupled to a surrounding matrix of magnetic material that is antiferromagnetic

Methodology Applied

Scientific EffectExchange coupling:

Implementation Method 2

Heating the magnetic recording disk temporarily reduces the coercivity of the magnetic media, which enables the read/write head to change the magnetization direction of a bit

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentUS20250391429A1Magnetic stack, and related data storage devices, systems, and methods

Publication Date: 2025.12.25 SEAGATE TECH LLC

AI summary

A magnetic stack having a magnetic recording layer. The magnetic recording layer includes a plurality of ferromagnetic, discrete regions located within a matrix of at least one magnetic composition that is antiferromagnetic. Each ferromagnetic, discrete region corresponds to a magnetic domain for storing a bit of data. Related data storage devices, systems, and methods.