Spin Injection Assisted Magnetic Recording Structure for Higher Areal Density
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Solution Overview
Problem
Current perpendicular magnetic recording (PMR) technologies face limitations in writability and areal density due to the saturation magnetization of magnetic materials, necessitating improved write field and field gradient at the main pole/write gap and write shield interfaces.
Innovation Solution
A spin injection assisted magnetic recording (SIAMR) device is introduced, comprising a ferromagnetic layer and spin preserving layers in the write gap, allowing spin polarized electrons to enhance local magnetic fields and gradients at the main pole/write shield interfaces, thereby improving linear and areal density capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the write head size is reduced to increase areal density, then the areal density capability is improved, but the writability degrades
Solution Approach 1:
A spin preserving layer is introduced as an intermediary between the ferromagnetic layer and the write shield, enabling spin-polarized current to flow through it and generate enhanced magnetic fields at the write gap interfaces, thereby improving writability without increasing head size
Solution Approach 2:
The invention changes the magnetic field generation mechanism by utilizing spin transfer torque from spin-polarized current to create localized magnetic fields and gradients, transitioning from purely current-driven fields to spin-mediated field enhancement, which improves writability while maintaining small head dimensions
2Stability of the object's composition
If conventional PMR technology is used to maintain saturation magnetization, then material stability is preserved, but write field and field gradient are insufficient
Solution Approach 1:
The spin preserving layer creates localized magnetic field enhancement specifically at the write gap interfaces (main pole/write gap and write shield/write gap), concentrating the magnetic force where it is most needed for writing, while the bulk materials maintain their saturation magnetization properties
Solution Approach 2:
The invention uses a composite structure combining ferromagnetic layers with spin preserving layers to achieve both stable saturation magnetization in the ferromagnetic components and enhanced write field through the spin-mediated interaction at the interfaces
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 SIAMR device enhances write and return fields, improving linear density and reliability while reducing current density requirements, thus overcoming limitations of conventional PMR writers.
Implementation Method 1
Spin transfer (spin torque) devices are based on a spin-transfer effect that arises from the spin dependent electron transport properties of ferromagnetic-spacer-ferromagnetic multilayers. When a spin-polarized current passes through a FM1/NM/FM2 multilayer in a CPP (current perpendicular to plane) configuration where FM1 and FM2 are first and second FM layers and NM is a non-magnetic spacer, the spin angular moment of electrons from FM1 that is incident on FM2 interacts with magnetic moments of FM2 near the NM/FM2 interface. Through this interaction, the electrons transfer a portion of their angular momentum to FM2.
Data Source
AI summary
A spin injection assisted magnetic recording structure is disclosed wherein a ferromagnetic (FM) layer and a spin preservation (SP) layer are formed between a main pole (MP) trailing side and a write shield (WS). Current (Ia) is injected into the FM layer and flows through the SP layer to the WS. As a result, spin polarized electrons from the FM layer generate a magnetization that enhances a local WS magnetization and return field. A lead to the FM layer may be stitched to enable lower resistance and improve reliability. The FM layer is separated from the MP trailing side with a write gap, and is recessed from the ABS to allow more overlap with the SP layer for lower current density while maintaining performance. Higher linear density and area density capability, and better reliability are achieved.