Thermally Assisted Magnetic Head Plasmon Unit Recess Design
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Solution Overview
Problem
In thermally assisted magnetic recording heads, the near-field light generating end of the plasmon generator and magnetic layer protrude over the air bearing surface during writing operations, potentially crashing the magnetic recording medium due to high temperature generation.
Innovation Solution
A write element design featuring a plasmon unit with a near-field light generating surface recessed from the air bearing surface by a predetermined distance, filled with a protective layer made of low light absorption materials, prevents protrusion and ensures safe operation during thermally assisted writing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plasmon generator and magnetic layer are positioned close to the air bearing surface for effective near-field light generation, then the thermally assisted writing performance is improved, but the risk of crashing the magnetic recording medium increases due to thermal expansion and protrusion
Solution Approach 1:
A protective layer is deposited over the plasmon generator and magnetic layer before operation. This protective layer acts as a cushion that prevents the plasmon generator from directly crashing the magnetic recording medium even when thermal expansion causes protrusion, while still allowing near-field light to pass through to the air bearing surface
Solution Approach 2:
The protective layer serves as an intermediary between the plasmon generator and the magnetic recording medium. It mediates the interaction by providing mechanical protection against crashing while maintaining optical transparency for near-field light generation, thus resolving the contradiction between performance and safety
2Use of energy by moving object
If the plasmon generator is allowed to expand freely during writing operations, then the near-field light generation efficiency is maintained, but the protrusion over the air bearing surface causes harmful contact with the recording medium
Solution Approach 1:
The protective layer is applied in advance to cushion the plasmon generator during thermal expansion. This allows the plasmon generator to expand freely for efficient near-field light generation while the protective layer prevents harmful protrusion and contact with the recording medium
Data Source
AI summary
A write element for a thermally assisted magnetic head slider includes an air bearing surface facing to a magnetic recording medium; a first magnetic pole, a second magnetic pole, and coils sandwiched between the first and the second magnetic poles; a waveguide for guiding light generated by a light source module mounted on a substrate; and a plasmon unit provided around the first magnetic pole and the waveguide, which has a near-field light generating surface for propagating near-field light to the air bearing surface. The near-field light generating surface of the plasmon unit is apart from the air bearing surface with a first predetermined distance to form a first recess, and the first recess is filled in with a protective layer. The thermally assisted magnetic head slider can prevent the plasmon unit from protruding over the air bearing surface, thereby improving the performance of thermally assisted magnetic head.