Dual Spin Hall Effect Layer Write Head for Magnetic Recording
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Solution Overview
Problem
Existing magnetic recording technologies face challenges with writability degradation as write head sizes shrink, leading to issues with overwrite, bit error rate, and reliability, particularly due to heating and synchronization difficulties in Spin Hall Effect assisted magnetic recording (SHAMR) designs.
Innovation Solution
A SHAMR device is developed with two Spin Hall Effect layers made of negative and positive giant Spin Hall Angle materials, separated by a non-magnetic conductor layer, where a current is applied across the conductor to generate spin transfer torque, enhancing the write and return fields without requiring synchronization with the write current, and maintaining uniform assist across the entire interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current is applied across a SHE layer in conventional SHAMR designs, then spin transfer torque is generated to assist writing, but heating and synchronization difficulties occur
Solution Approach 1:
A non-magnetic conductor layer is introduced as an intermediary between the negative SHA material layer and positive SHA material layer. This conductor layer serves as a current distribution medium that enables spin transfer torque generation while avoiding direct current application to the SHE layers, thereby reducing heating effects and eliminating synchronization requirements with the write current
2Quantity of substance
If write head size is reduced to increase data areal density, then higher areal density is achieved, but writability degrades
Solution Approach 1:
The invention changes the magnetic field parameters by generating additional spin transfer torque fields through the dual-layer SHE structure. This creates enhanced effective write fields that compensate for the reduced head size, allowing high areal density to be achieved without sacrificing writability. The spin transfer torque from both negative and positive SHA materials working in opposition creates a stronger net assist field
3Reliability
If a current is applied across a SHE layer synchronized with write current, then overwrite is improved, but device complexity increases due to synchronization requirements
Solution Approach 1:
The non-magnetic conductor layer automatically distributes current between the negative SHA material layer and positive SHA material layer based on the local magnetic field conditions and material properties. This self-service current distribution eliminates the need for external synchronization control, as the system autonomously generates the appropriate spin transfer torque assist fields without requiring complex timing or control circuitry
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 overwrite, bit error rate, and transition sharpness while avoiding current thresholds and heating, enabling efficient magnetic recording with ultra-short time scales and compatibility with varying write gap thicknesses.
Implementation Method 1
a current (Ia) is applied from the SHE layer across the conductor layer when the SHE layer is a negative giant SHA material, or Ia is applied from the conductor layer across the SHE layer made of a positive SHA material in order to produce spin transfer torque that causes a local MP magnetization or a local TS magnetization to tilt
Implementation Method 2
Spin Hall Effect (SHE) is a physics phenomenon discovered in the mid 20th century, and is described by M. Dyaknov et al. in Physics Lett. A, Vol. 35, 459 (1971). Similar to a regular Hall Effect where conduction carriers with opposite charges are scattered to opposite directions perpendicular to the current density due to a certain scattering mechanism, SHE causes electrons with opposite spins to be scattered to opposite directions perpendicular to the charge current density as a result of strong spin-orbit coupling in the conducting layer
Implementation Method 3
enhance a write field or return field, respectively, thereby improving overwrite (OW) and bit error rate (BER) and reliability
Data Source
AI summary
A Spin Hall Effect (SHE) assisted magnetic recording device is disclosed wherein a SHE layer and a conductor layer (CL) are formed between a main pole (MP) trailing side and a trailing shield (TS). When the SHE layer is a negative Spin Hall Angle (SHA) material, current (Ia) flows from the SHE layer across the CL to a lead back to a source, or across the CL to one of the MP and TS. For a SHE layer with a positive SHA material, Ia flows from one of the MP or TS or from a lead across the CL to the SHE layer. Spin polarized current in the SHE layer applies spin transfer torque that tilts a local MP magnetization to a direction that enhances a MP write field, or that tilts a local TS magnetization to a direction that increases the TS return field and improves bit error rate.