Magnetic Write Head Ampere Field Alignment for Cross-Track Interference
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Solution Overview
Problem
Magnetic recording write heads experience cross-track interference (XTI) due to stray magnetic fields affecting adjacent and distant tracks, leading to data overwriting, which is exacerbated by the inherent magnetization of side shields during manufacturing.
Innovation Solution
Incorporating an electrically-conductive structure in the write gap between the write pole and the trailing shield, with electrical current directed through it to generate a circular Ampere field that aligns with the magnetization direction of the write head side shields, minimizing XTI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrical current is directed through the write gap to generate Ampere field for assisting magnetization reversal, then write speed is improved, but cross-track interference increases due to misalignment with side shield magnetization
Solution Approach 1:
The invention changes the direction parameter of electrical current flow through the write gap to align the generated Ampere field with the magnetization direction of the side shields. This parameter adjustment ensures that the current direction is optimized to minimize cross-track interference while maintaining the beneficial magnetization switching assistance, thereby resolving the contradiction between write speed improvement and harmful interference reduction.
2Quantity of substance
If recording density is increased by reducing magnetic grain size, then areal density is improved, but thermal stability deteriorates due to increased magnetocrystalline anisotropy requirements
Solution Approach 1:
The invention introduces an intermediary mechanism (current-assisted writing with properly oriented Ampere field) that enables writing to higher coercivity media with smaller magnetic grains. The Ampere field generated by current through the write gap acts as a mediator that provides the additional field needed to overcome the increased magnetocrystalline anisotropy of smaller grains, thereby enabling high areal density while maintaining thermal stability through appropriate grain size selection.
3Speed
If main pole magnetization switching time is reduced for high data rates, then write speed is improved, but available magnetic flux decreases due to low-frequency flux dominance
Solution Approach 1:
The invention merges two magnetic field sources: the conventional time-varying field from the main pole and the auxiliary Ampere field generated by current through the write gap. This combination allows the main pole to switch magnetization faster (improving write speed) while the Ampere field compensates for the reduced low-frequency flux, maintaining sufficient total magnetic flux for effective writing at high data rates.
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 effectively reduces cross-track interference by ensuring the Ampere field direction matches the magnetization direction of the side shields, thereby minimizing signal loss and maintaining data integrity across tracks.
Implementation Method 1
electrical current is directed through it to generate a circular Ampere field that aligns with the magnetization direction of the write head side shields
Data Source
AI summary
A magnetic recording write head has an electrically-conductive structure in the write gap between the write pole and the trailing shield and electrical circuitry for directing current through the write gap. The current through the electrically-conductive structure generates a circular Ampere field which, at the disk-facing end of the write pole, is substantially parallel to the disk-facing end of the write pole. The electrically-conductive structure in the write gap may be a STO or an electrically-conductive layer that is not part of a STO. The current direction through the electrically-conductive structure in the write gap is selected so that the generated Ampere field at the write pole end is in substantially the same direction as the magnetization direction of the write head side shields, which has been discovered to result in minimization of cross-track interference.