MAMR Head Back Gap Resistive Magnetic Material
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Solution Overview
Problem
Conventional microwave-assisted magnetic recording (MAMR) head structures face low write magnetic field responsivity due to high magnetic circuit resistance in the back gap, which is exacerbated by the use of non-magnetic materials like alumina and insufficient performance with magnetic materials like permalloy, leading to inefficient current flow and reduced recording density.
Innovation Solution
Incorporating a highly resistive magnetic material, such as ferrite or granular magnetic materials, in the yoke, main pole, return pole, and back gap to enhance the write magnetic field responsivity while ensuring efficient current flow to the spin torque oscillator, characterized by resistivity in the range of 1 Ωm to 1×104 Ωm and a saturation magnetic flux density of not less than 0.1 T, allowing for improved recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alumina is employed as the back gap material for electrical insulation, then current flow efficiency to STO is improved, but magnetic circuit resistance increases and write magnetic field responsivity deteriorates
Solution Approach 1:
The patent employs a composite structure where a non-magnetic material layer (alumina for insulation) is combined with a magnetic material layer (FeCoNi for magnetic circuit continuity) in the back gap region. This composite approach allows simultaneous achievement of electrical insulation and maintained magnetic circuit performance, resolving the contradiction between insulation requirements and magnetic field generation efficiency.
2Power
If permalloy is employed as the back gap material for magnetic circuit continuity, then write magnetic field responsivity is improved, but electrical resistance decreases and current flow to STO deteriorates
Solution Approach 1:
The patent uses a composite back gap structure with distinct functional layers: a non-magnetic insulating layer (alumina) positioned to provide electrical insulation, and a magnetic material layer (FeCoNi permalloy) positioned to maintain magnetic circuit continuity. This layered composite resolves the contradiction by assigning different materials to different functional requirements within the same component region.
Solution Approach 2:
The patent applies different material properties to different locations within the back gap structure. The non-magnetic material is positioned where electrical insulation is critical, while the magnetic material is positioned where magnetic flux continuity is essential. This spatial differentiation of material qualities allows simultaneous satisfaction of both contradictory requirements.
3Quantity of substance
If recording bit size is miniaturized to increase recording density, then storage capacity is improved, but component performance and manufacturing precision requirements worsen
Solution Approach 1:
The patent changes the magnetic material composition parameters in the back gap region, specifically using FeCoNi alloy with optimized composition ratios (Fe:Co:Ni in ranges such as 70:20:10 to 80:10:10). This parameter optimization enhances magnetic properties and write field efficiency, compensating for the challenges posed by miniaturization and enabling higher recording densities while maintaining manufacturing feasibility.
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 use of highly resistive materials in the MAMR head structure significantly enhances write magnetic field responsivity and ensures efficient current delivery to the spin torque oscillator, thereby improving recording density and addressing the limitations of conventional MAMR heads.
Implementation Method 1
microwave-assisted magnetic recording (MAMR) head with highly resistive magnetic material... spin torque oscillator (STO) positioned above the main pole
Implementation Method 2
a back gap layer positioned between the yoke and the return pole, wherein at least one of the yoke, the main pole, the return pole, and the back gap layer comprises a highly resistive magnetic material
Data Source
AI summary
In one embodiment, a high-frequency magnetic field-assisted magnetic recording (MAMR) head includes: a yoke adapted for facilitating magnetic flux through the MAMR head; a main pole magnetically coupled to the yoke and adapted for producing a writing magnetic field; a return pole spaced from the main pole; a spin torque oscillator (STO) positioned above the main pole; and a back gap layer positioned between the yoke and the return pole, where at least one of the yoke, the main pole, the return pole, and the back gap layer comprises a highly resistive magnetic material.