Microwave-Assisted Magnetic Recording Head with Adjacent Track Interference Suppression
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Solution Overview
Problem
At high data densities, it is challenging to write stable magnetic bits while avoiding adjacent track interference, as increased magnetic coercivity requires stronger write fields, which are difficult to generate with shrinking write pole sizes, and local heating methods inadvertently affect adjacent tracks.
Innovation Solution
A magnetic write head with a centrally disposed magnetic assist element generating an oscillating magnetic field to aid writing, accompanied by non-assist elements on either side that counteract the assist field to suppress adjacent track interference, effectively narrowing the track width and increasing data density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the magnetic coercivity of the media is increased to maintain stable magnetic bits at very small bit sizes, then the stability of recorded bits is improved, but the field strength required to record to the medium must be increased, which becomes difficult to generate with shrinking write pole sizes
Solution Approach 1:
The patent changes the physical state of the magnetic medium by locally heating it to the Curie temperature, which temporarily alters the magnetic coercivity parameter. This allows the medium to be more easily written to during the heated state, and then returns to its high-coercivity stable state after cooling, resolving the contradiction between bit stability and writeability
Solution Approach 2:
The patent employs periodic microwave pulses to cyclically heat and cool the magnetic medium at the write location. This periodic thermal action creates windows of opportunity for writing bits when the medium is in its low-coercivity heated state, while maintaining overall bit stability when the medium returns to its normal high-coercivity state
2Ease of manufacture
If local heating methods are used to lower the coercivity of the media for recording, then the writeability is improved, but adjacent tracks are inadvertently heated as well, which can lead to erasure of or interference with adjacent data tracks
Solution Approach 1:
The patent applies local quality by using a focused write pole that concentrates microwave energy and heating only at the specific track location where writing is needed. This localized heating approach ensures that adjacent tracks remain at their normal temperature and are not affected, resolving the contradiction between writeability and adjacent track protection
Solution Approach 2:
The patent segments the heating function by separating the microwave generation from the write pole structure, allowing independent control of the heated region. The write pole acts as a spatial filter that confines the thermal effect to only the intended track, preventing harmful thermal diffusion to adjacent tracks
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 approach enhances writing in the desired narrow region while preventing interference with adjacent tracks, thereby improving writeability and data density without erasing adjacent data.
Implementation Method 1
An electrically conductive write coil induces a magnetic flux through the write coil. This results in a magnetic write field being emitted toward the adjacent magnetic medium
Implementation Method 2
The magnetic write field locally magnetizes the medium and then travels through the medium and returns to the write head
Implementation Method 3
A magnetoresistive sensor such as a GMR or TMR sensor can be employed for sensing magnetic fields from the rotating magnetic disk
Implementation Method 4
A magnetoresistive sensor such as a GMR or TMR sensor can be employed for sensing magnetic fields from the rotating magnetic disk
Implementation Method 5
When the magnetizations of the pinned and free layers are parallel with respect to one another, scattering is minimal and when the magnetizations of the pinned and free layer are antiparallel, scattering is maximized. Changes in scattering alter the resistance of the spin valve sensor in proportion to cos θ
Data Source
AI summary
A magnetic write head for magnetic data recording that incorporates a novel magnetic oscillation generator stricture that sets up a magnetic oscillation in the magnetic media for improving writing and that also narrows the write width and reduces adjacent track interference by suppressing writing in regions outside of the desired data track. The magnetic oscillation generating structure includes a centrally disposed magnetic assist element that generates an oscillating magnetic field that oscillates in a direction that will assist the write pole in writing to the magnetic medium. The magnetic oscillation generating structure also includes first and second magnetic non-assist elements at either side of the assist element. The non-assist elements generate a magnetic field that oscillates in a second direction that is opposite to the first direction, which counteracts the magnetic write assist from the centrally disposed magnetic assist element and acts to suppress writing in these side regions.