Dual Spin Polarization Layer STO for MAMR AC Field Strength
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Solution Overview
Problem
Current microwave-assisted magnetic recording (MAMR) technologies face challenges in generating a high AC magnetic field due to insufficient spin torque, primarily because the magnetization of the field generation layer (FGL) is not adequately oriented in the in-plane direction, leading to a low AC magnetic field strength.
Innovation Solution
The proposed MAMR head structure includes a spin-torque oscillator (STO) with a first and second spin polarization layer (SPL) having magnetic anisotropy perpendicular to the film surface, along with non-magnetic transmission layers, which enables T-mode and U-mode oscillations, increasing the in-plane component of the FGL magnetization and thus the AC magnetic field intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single spin polarization layer (SPL) is used in the STO structure, then the device complexity is reduced, but the AC magnetic field strength is insufficient because the FGL magnetization cannot be fully oriented in the in-plane direction
Solution Approach 1:
The single SPL is divided into two separate SPLs (first SPL and second SPL) positioned at different locations relative to the FGL. The first SPL is positioned below the FGL while the second SPL is positioned above the FGL, allowing each to independently contribute to spin torque generation and enable complete in-plane magnetization orientation of the FGL.
Solution Approach 2:
The invention transitions from a single-layer SPL configuration to a multi-layer configuration spanning both sides of the FGL. By adding the second SPL above the FGL (another dimension in the layer stack), the system achieves enhanced spin torque effect and complete in-plane magnetization orientation that cannot be achieved with a single SPL.
2Ease of manufacture
If the FGL magnetization is oriented perpendicular to the film surface, then the STO structure is simpler to manufacture, but the AC magnetic field generation is insufficient because spin torque acts only at the boundary plane
Solution Approach 1:
The invention creates different magnetic orientation requirements for different regions of the FGL. By positioning SPLs at both boundaries of the FGL, the system achieves uniform in-plane magnetization orientation throughout the entire FGL thickness, rather than having mixed perpendicular and in-plane orientations that occur with single SPL configurations.
3Power
If a dual spin polarization layer (SPL) structure is implemented, then the AC magnetic field strength and spin torque efficiency are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The first SPL and second SPL are merged with the FGL to form an integrated STO structure where the SPLs are positioned immediately adjacent to the FGL boundaries. This merging approach allows the dual SPL configuration to achieve enhanced spin torque effect while minimizing the overall device footprint and reducing manufacturing complexity compared to separated configurations.
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 configuration results in a stronger AC magnetic field and improved oscillation performance, enhancing the signal-to-noise ratio (SNR) and assist effect compared to conventional structures.
Implementation Method 1
a spin-torque oscillator (STO) positioned near the main magnetic pole, the STO including a first perpendicular magnetic layer positioned above the main magnetic pole, wherein the first perpendicular magnetic layer is a first spin polarization layer (SPL 1)
Implementation Method 2
By conducting current 510 to the STO 500 when a magnetic field 508 is applied from a writer to the STO 500, the STO 500 oscillates, and an AC magnetic field is applied to the medium
Data Source
AI summary
In one embodiment, a MAMR head includes a main magnetic pole, a STO positioned near the main magnetic pole, the STO including a first perpendicular magnetic layer positioned above the main magnetic pole, wherein the first perpendicular magnetic layer is a first spin polarization layer having an axis of magnetic anisotropy in a direction perpendicular to a film surface, a first non-magnetic transmission layer positioned above the first perpendicular magnetic layer, a magnetic layer effectively having a plane of easy magnetization in the film surface positioned above the first non-magnetic transmission layer, the magnetic layer being a FGL, a second non-magnetic transmission layer positioned above the magnetic layer, and a second perpendicular magnetic layer positioned above the second non-magnetic transmission layer, wherein the second perpendicular magnetic layer is a second spin polarization layer having magnetic anisotropy in the direction perpendicular to the film plane.