Spin Torque Oscillator Multilayer Seed for Magnetic Recording
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Solution Overview
Problem
Current magnetic recording heads face challenges in achieving high recording densities due to the limitations of write field effectiveness and reliability, particularly requiring high voltage and current for energy-assisted recording technologies like MAMR, which can degrade components and hinder performance.
Innovation Solution
A magnetic recording head design incorporating a spintronic device with a spin torque layer and a multilayer seed layer, including a high etch rate layer, heat dissipation layer, and cooling layer, positioned between the main pole and trailing shield, to enhance write field generation and reduce critical current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage and current are applied to produce write field enhancement in energy-assisted recording, then the write field effectiveness is improved, but the lifetime and reliability of the write head deteriorate due to component degradation
Solution Approach 1:
The patent changes the magnetic anisotropy parameters of the spin torque layer by adjusting composition (e.g., CoFeB with boron content optimization) and thickness (e.g., 3-5 nm range), which modifies the magnetization switching characteristics and reduces the critical current density required for operation, thereby lowering the operating voltage and current while maintaining write field effectiveness
Solution Approach 2:
The patent employs composite material structures including spin torque layers composed of CoFeB or CoFe alloys combined with specific seed layers and protective layers, creating a multi-layer composite structure that optimizes both the magnetic switching efficiency and the thermal/electrical stability, enabling reliable operation at reduced power levels
2Use of energy by moving object
If the moment-thickness product of the energy-assist magnetic layer is reduced to lower voltage or current requirements, then power consumption is decreased, but the writer performance and areal density capability are hindered
Solution Approach 1:
The patent optimizes the thickness and magnetic moment parameters of the spin torque layer independently, using ultra-thin layers (3-5 nm) with high magnetic moment materials (CoFeB with optimized boron content) to achieve low critical current density while maintaining sufficient magnetic strength for high areal density recording, thus decoupling the traditional trade-off between power consumption and productivity
Solution Approach 2:
The patent applies local quality optimization by creating a spin torque layer with spatially varying composition and thickness profiles, where the magnetic properties are locally tuned to achieve efficient spin torque generation at minimal power while maintaining the overall magnetic field strength required for high-density recording
3Productivity
If the main pole surface area is decreased to achieve higher recording density, then the recording density is improved, but the writing field strength is reduced
Solution Approach 1:
The patent replaces the traditional mechanical/electromagnetic field generation approach with a spintronic mechanism, where spin-polarized current flowing through the spin torque layer generates a localized magnetic field via the spin Hall effect or Rashba effect, enabling strong writing fields from sub-10 nm scale structures that would be impossible with conventional electromagnetic approaches
Solution Approach 2:
The patent utilizes changes in magnetic anisotropy energy parameters and spin polarization parameters to enhance the efficiency of spin torque-driven field generation, allowing ultra-small main poles to produce sufficient writing fields through optimized spin transport properties rather than relying on geometric scaling of traditional electromagnetic structures
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 the shape and reliability of the spintronic device, reducing the critical current and enabling efficient magnetic recording with lower voltage and current, thus enhancing areal density capability and material utilization.
Implementation Method 1
a heat dissipation layer comprising Ru disposed in contact with the optional high etch rate layer
Implementation Method 2
a cooling layer comprising Cr disposed in contact with the heat dissipation layer and the main pole
Implementation Method 3
the STO produces a high-frequency AC field, such as in a microwave frequency band, that reduces an effective coercivity of a magnetic recording medium
Implementation Method 4
allows writing of the magnetic recording medium at lower magnetic writing fields emanated from the write pole
Data Source
AI summary
The present disclosure generally relates to a magnetic recording device having a magnetic recording head comprising a spintronic device. The spintronic device is disposed between a main pole and a trailing shield at a media facing surface. The spintronic device comprises a spin torque layer (STL) and a multilayer seed layer disposed in contact with the STL. The spintronic device may further comprise a field generation layer disposed between the trailing shield and the STL. The multilayer seed layer comprises an optional high etch rate layer, a heat dissipation layer comprising Ru disposed in contact with the optional high etch rate layer, and a cooling layer comprising Cr disposed in contact with the heat dissipation layer and the main pole. The high etch rate layer comprises Cu and has a high etch rate to improve the shape of the spintronic device during the manufacturing process.