Stitched Pole Tip Magnetic Writer Design
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Solution Overview
Problem
High-density magnetic recording technologies face challenges in increasing data rate without increasing bit error rate (BER) due to low damping constants in current magnetic materials and accidental data erasure from remnant magnetization, requiring materials with high saturation magnetization and low anisotropy fields.
Innovation Solution
The use of high moment Co, Fe, Ni alloys doped with small percentages of rare earth and/or 3d-5d transition metals to increase the damping constant, combined with a stitched pole tip design optimizing both high damping and saturation magnetization, allowing for a device capable of high data rate recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If magnetic materials with high saturation magnetization are used to provide high intensity writing field, then the writing capability is improved, but the damping constant remains small causing slow response time
Solution Approach 1:
The patent changes the material parameter (damping constant) by doping high saturation magnetization materials with rare earth elements or transition metals. This modifies the magnetic material's intrinsic properties to achieve both high writing field intensity and fast response time simultaneously.
Solution Approach 2:
The patent creates composite magnetic materials by combining high saturation magnetization materials (Fe, Co, Ni alloys) with doping elements (rare earth or transition metals). This composite structure provides both the high writing field intensity from the base material and the enhanced damping constant from the dopants.
2Object-generated harmful factors
If magnetic materials with low anisotropy field are used to eliminate remnant magnetization, then data erasure is minimized, but the saturation magnetization may be insufficient for high intensity writing field
Solution Approach 1:
The patent applies different material compositions to different parts of the writer structure. The pole tip uses material optimized for low anisotropy field to minimize remnant magnetization, while the yoke uses material optimized for high saturation magnetization to provide strong writing field intensity.
Solution Approach 2:
The patent uses composite magnetic materials with controlled anisotropy and saturation magnetization properties. By carefully selecting base materials and dopants, the composite provides both low remnant magnetization and sufficient writing field intensity.
3Reliability
If the writer structure is divided into multiple sub-structures with different material compositions, then both high damping constant and high saturation magnetization are achieved, but the device complexity increases
Solution Approach 1:
The patent divides the writer into functionally distinct segments: pole tip made of high damping constant material and yoke made of high saturation magnetization material. This segmentation allows each part to be optimized for its specific function while maintaining overall system performance.
Solution Approach 2:
The patent implements local quality optimization by assigning different material compositions to different spatial locations within the writer structure. The pole tip region uses high damping material while the yoke region uses high saturation magnetization material, matching material properties to functional requirements.
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 enables a magnetic writer to achieve high data rates with reduced bit error rates and minimized data erasure, by enhancing the damping constant while maintaining high saturation magnetization, thus supporting efficient high-density magnetic recording.
Implementation Method 1
The damping constants of the high saturation magnetization (Ms) materials used in present day writers (Fe, Co, Ni alloys) is small, being in the range of from 0.002 to 0.02. These materials are high moment Co, Fe, Ni alloys doped with a small percentage of rare earth and/or 3d-5d transition metals that will increase the damping constant significantly.
Implementation Method 2
During the writing process, magnetization will follow the Landau-Lifshitz-Gilbert equation: where M is the magnetization, γ is the gyromagnetic coefficient, Heff is the field, including the applied field, the demagnetization field, and the anisotropic field.
Implementation Method 3
The value of α determines how fast M aligns with Heff, as illustrated schematically by the two examples shown in FIGS. 1a and 1b. In FIG. 1a α is relatively small while in FIG. 1b α is relatively large.
Data Source
AI summary
A high speed magnetic data writer containing a stitched pole tip that works in conjunction with the main pole is disclosed, together with a process for their manufacture. The material composition of each of these two sub-structures is slightly different; one sub-structure is optimized for high magnetic damping while the other sub-structure is optimized for high saturation magnetization.