Dual Write Head Design for Magnetic Recording Density

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Solution Overview

Problem

Conventional magnetic recording heads face challenges in achieving optimal areal density capacity due to the trade-off between bits per inch (BPI) and tracks per inch (TPI) capabilities, with side shields causing magnetic shunting and adjacent track erasure.

Innovation Solution

A dual write head design is introduced, featuring a first write head with a wider write and a second write head with a narrower write, both equipped with energy-assisted magnetic recording (EAMR) structures and non-magnetic conductive structures, where the second write head includes a side shield comprising a heavy metal and magnetic layer to enhance current efficiency and uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If side shields are added to reduce adjacent track erasure, then TPI capability is improved, but magnetic shunting occurs in side gaps reducing BPI capability

Engineering Contradiction:

Improvetrack writing precisionVSAvoidbits per inch capability

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent divides the write head into two separate write heads: a first write head without side shields optimized for BPI capability, and a second write head with side shields optimized for TPI capability. This segmentation allows each head to specialize in one function, resolving the contradiction between adjacent track erasure protection and magnetic shunting.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the system (first write head and second write head) are given different properties: the first write head has no side shields for maximum write field strength, while the second write head has side shields for precise track definition. This local quality differentiation allows simultaneous optimization of both BPI and TPI capabilities.

Inventive Principle:

Principle #3Local quality

2Productivity

If a single write head is used to increase BPI capability with strong write field, then bits per inch is improved, but adjacent track erasure occurs

Engineering Contradiction:

Improvebits per inch capabilityVSAvoidtrack writing precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The write function is segmented into two specialized heads: the first write head provides strong write field for BPI optimization without side shields, while the second write head provides precise track definition with side shields. This eliminates the need for a single head to compromise between these conflicting requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second write head with side shields acts as an intermediary that refines and defines the tracks written by the first write head. It corrects adjacent track erasure issues without significantly reducing the BPI capability established by the first head.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If side shields are used to improve TPI capability, then tracks per inch is improved, but current efficiency and uniformity are reduced

Engineering Contradiction:

Improvetracks per inch capabilityVSAvoidcurrent efficiency

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the write head system so that the second write head with side shields is dedicated to TPI optimization, while the first write head handles BPI optimization. This allows the side shields to be present only where needed for TPI, minimizing their negative impact on current efficiency while maintaining TPI capability.

Inventive Principle:

Principle #1Segmentation

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 design improves areal density capacity by optimizing BPI and TPI capabilities without causing adjacent track erasure or magnetic shunting, enabling efficient and precise data writing and reading.

Implementation Method 1

The second write head comprises an energy-assisted magnetic recording element or stack

Methodology Applied

Scientific EffectSpin transfer torque (STT):

Implementation Method 2

The side shield comprises a first layer comprising a heavy metal material or a topological insulator material and a second layer comprising a magnetic material

Methodology Applied

Scientific EffectSpin orbital torque (SOT):

Implementation Method 3

The second write head comprises an energy-assisted magnetic recording element or stack

Methodology Applied

Scientific EffectEnergy-assisted magnetic recording (EAMR):

Data Source

PatentUS10839831B1Dual writer designs with SOT and STT assisted recording

Publication Date: 2020.11.17 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

The present disclosure generally relates to a magnetic media drive employing a magnetic recording head. The magnetic recording head comprises a first write head and a second write head. The first write head comprises a first main pole, a first yoke having a first length, and a first coil wrapped around the first yoke. The second write head comprises a second main pole, a second yoke having a second length, a second coil wrapped around the second yoke, and a side shield surrounding two or more surfaces of the second main pole. The side shield comprises a heavy metal layer and a magnetic layer. The second write head comprises an energy-assisted magnetic recording element or stack. The second write head comprises a non-magnetic conductive structure to enable maximum current efficiency and uniformity. A write of the first write head is wider than that of the second write head.