Bi-polar Complementary Servo Patterns for Signal Amplitude

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Solution Overview

Problem

Current methods for producing bi-polar servo structures in patterned media face challenges in achieving regular bi-polar magnetization direction and doubling servo signal amplitude while avoiding costly baseline compensation and random magnetization issues.

Innovation Solution

The method involves creating bi-polar complementary structure patterns using direct-write e-beam recording with magnetically isolated and connected features, including finger structures with intentional weak nucleation points, which allow for bulk DC initialization and thermally stable servo-fields, interlacing to generate regular bi-polar servo signals without explicit writing during in-drive initialization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional methods are used to produce servo structures, then manufacturing process is simpler, but regular bi-polar magnetization direction cannot be achieved and baseline compensation is required

Engineering Contradiction:
Improvemagnetization direction regularityVSAvoidstructure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The servo structure is divided into two complementary components: magnetically isolated features and magnetically connected features. Each component creates a specific magnetic polarity pattern, and when combined, they generate the desired bi-polar magnetization direction without requiring baseline compensation. This segmentation allows independent optimization of each component's magnetic properties.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the servo structure are assigned different magnetic properties. The magnetically isolated features have one set of magnetic characteristics while the magnetically connected features have complementary characteristics. This local differentiation enables precise control over the magnetization direction in different areas, achieving regular bi-polar patterns.

Inventive Principle:
Principle #3Local quality

2Power

If single polarity servo structures are used, then structure is simpler, but servo signal amplitude is limited and baseline compensation is needed

Engineering Contradiction:
Improveservo signal amplitudeVSAvoidstructure complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

Two servo structure components with opposite magnetic polarities are merged into a single complementary pattern. The magnetically isolated features and magnetically connected features work together to generate both positive and negative servo signals, effectively doubling the total servo signal amplitude while eliminating the need for baseline compensation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The servo structure uses a composite approach combining two different magnetic feature types with complementary properties. This composite structure enables generation of bi-polar signals with enhanced amplitude, as each component contributes one polarity while the other component provides the opposite polarity, creating a balanced high-amplitude signal.

Inventive Principle:
Principle #40Composite materials

3Reliability

If strong nucleation points are used in all structures, then magnetization initialization is more reliable, but random magnetization directions occur and bi-polar pattern is lost

Engineering Contradiction:
Improvemagnetization initialization reliabilityVSAvoidmagnetization direction control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

Weak nucleation points are strategically placed only in specific structures where they are needed to initiate reversal, while other structures maintain strong nucleation points to preserve their magnetization state. This localized approach ensures that reversal occurs only in the intended locations, maintaining the bi-polar pattern while achieving reliable initialization.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The structure is designed with intentional weak nucleation points that preemptively prepare specific regions for reversal when the DC-field is removed. By pre-positioning these weak points in the correct locations, the system ensures that when initialization occurs, the magnetization reverses in the intended pattern rather than randomly, thereby preventing the loss of bi-polar structure.

Inventive Principle:
Principle #9Preliminary anti-action

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 ensures a regular bi-polar magnetization direction, doubles the servo signal amplitude, and avoids baseline compensation, resulting in thermally stable and robust servo-fields with reduced overhead and potential for enhanced data storage performance.

Implementation Method 1

direct-write e-beam recording

Methodology Applied
Scientific EffectElectron Beam: Electron Beam

Implementation Method 2

bulk DC initialization

Methodology Applied
Scientific EffectMagnetic Field: Magnetic Field

Implementation Method 3

magnetically connected features

Methodology Applied
Scientific EffectMagnetism: Magnetism

Implementation Method 4

dipolar interaction with its surroundings

Methodology Applied
Scientific EffectDipolar interaction:

Implementation Method 5

intentional weak nucleation points

Methodology Applied
Scientific EffectNucleation: Nucleation

Implementation Method 6

unobstructed domain-wall motion

Methodology Applied
Scientific EffectDomain-wall motion:

Data Source

PatentUS9230589B2Method for producing bi-polar complementary structure patterns
Publication Date: 2016.01.05 SEAGATE TECH LLC

AI summary

The embodiments disclose a method including creating at least one first structure including magnetically isolated features in servo fields, and creating at least one second structure including finger-structure patterns including intentional weak nucleation points in servo fields to create a regular bi-polar magnetization direction after bulk DC initialization, and wherein the first and second structures form bi-polar complementary structure patterns.