Binary Anisotropy Media Phase Transition for HAMR
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Solution Overview
Problem
Conventional hard disk drives face limitations in area density due to constraints on magnetic grain size and thermal stability, and current heat-assisted magnetic recording (HAMR) technologies require high temperatures that can cause medium structural variations and slow magnetization re-occurrence.
Innovation Solution
A magnetic microstructure known as binary anisotropy media, comprising a magnetic storage layer, a magnetic assist layer, and a phase transition interlayer made of materials like FeRh, which switches from antiferromagnetic to ferromagnetic at a temperature below the Curie temperature, allowing for robust data recording with reduced heating energy and write fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If heat-assisted magnetic recording is used to reduce write field requirements, then magnetic recording becomes feasible at elevated temperatures, but the medium requires heating to relatively high temperatures that cause structural variations and slow magnetization re-occurrence
Solution Approach 1:
The invention changes the magnetic anisotropy parameter by using a phase transition material that switches from antiferromagnetic to ferromagnetic state. This phase transition occurs at a lower temperature than the Curie temperature, enabling write field reduction without requiring high temperature heating that causes structural variations
Solution Approach 2:
The invention utilizes the phase transition of a material (such as FeRh) that transitions from antiferromagnetic to ferromagnetic state at a specific transition temperature. This phase transition enables the magnetic assist layer to couple with the storage layer, reducing the effective anisotropy field and allowing recording at lower temperatures than conventional HAMR
2Reliability
If the medium is heated to Curie temperature for magnetization re-occurrence, then data recording can be accomplished, but the heating energy required is high and rapid heat dissipation is needed to prevent lateral thermal expansion
Solution Approach 1:
The invention changes the operational temperature parameter from Curie temperature to a lower phase transition temperature. The phase transition material switches magnetic states at this lower temperature, achieving the same magnetization control function with significantly reduced heating energy requirements
Solution Approach 2:
The phase transition material acts as an intermediary between the write head and the storage layer. It mediates the magnetic coupling by transitioning from antiferromagnetic to ferromagnetic state, enabling efficient magnetic field transfer without requiring direct high-temperature heating of the storage layer
3Reliability
If conventional magnetic recording is used, then thermal stability is maintained, but area density is limited by the inability to generate sufficient magnetic field to overcome anisotropy constraints
Solution Approach 1:
The invention applies local quality by creating a magnetic assist layer with specific phase transition properties that is locally coupled to the storage layer. This localized phase transition and magnetic coupling enables reduced write field requirements specifically at the recording location, allowing smaller magnetic grains and higher area density while maintaining thermal stability
Solution Approach 2:
The invention uses composite material structure consisting of a storage layer and a phase transition assist layer. This composite structure combines the thermal stability of the storage layer with the field-reduction capability of the phase transition material, enabling both high area density and maintained thermal stability
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
Enables recording at temperatures below the Curie temperature with significantly reduced heating energy and write fields, achieving high area density and thermal stability while avoiding structural variations, and allows for rapid magnetization switching within the deep sub-nanosecond regime.
Implementation Method 1
The phase transition layer comprises a material, such as FeRh, that switches from antiferromagnetic at ambient to ferromagnetic at a transition temperature
Implementation Method 2
When the interlayer changes to the ferromagnetic phase (i.e., when it is heated to or above the transition temperature), the interlayer couples the magnetic moments of the storage and assist layers ferromagnetically
Implementation Method 3
recording to occur in the deep sub-nanosecond regime and with much less heating energy than that used in Curie temperature writing
Data Source
AI summary
A method of writing binary data comprising (i) heating a magnetic microstructure from an initial temperature to an above-ambient temperature that is not less than a transition temperature for the magnetic microstructure, which causes a phase transition interlayer of the magnetic microstructure to transition from an antiferromagnetic phase to a ferromagnetic phase; and (ii) reversing an orientation of magnetization of a magnetic storage layer of the magnetic microstructure with a magnetic field while the phase transition interlayer is in the ferromagnetic phase.