Magnetic Domain Wall Storage Using Spin Torque and Thermal Assistance
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Solution Overview
Problem
Conventional nonvolatile information storage devices face issues such as wear and tear in rotating parts, slow reading and writing speeds, short life spans, limited recording density, and high manufacturing costs, particularly with magnetic domain wall movement-based devices struggling to apply fringe field writing methods effectively and facing challenges with thicker magnetic layers.
Innovation Solution
An information storage device utilizing a heating unit to heat a first magnetic layer with perpendicular magnetic anisotropy, combined with a magnetic field applying unit to form and move magnetic domains, allowing for efficient data storage and retrieval through the movement of magnetic domain walls, and incorporating a light shielding wall to control light emission and a conductive line for current application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fringe field writing method is used, then magnetic domain walls can be moved, but the method cannot be applied to magnetic layers with relatively large magnetic anisotropic energy
Solution Approach 1:
The patent changes the writing mechanism from fringe field-based to spin torque-based, fundamentally altering the physical parameter used for writing. This allows the system to overcome the limitation of large magnetic anisotropic energy by using spin-polarized current to directly exert torque on the magnetic moments, enabling reliable writing in magnetic layers that were previously inaccessible to fringe field methods
Solution Approach 2:
The patent replaces the mechanical fringe field writing system with a spin torque-based writing system. Instead of using external magnetic fields generated by write heads, the system uses spin-polarized electrons to exert torque on the magnetic layer, substituting a field-based mechanism with a particle-based quantum mechanical effect
2Volume of moving object
If spin torque writing method is used, then writing can be achieved in thin magnetic layers, but if the thickness increases by about 3 nm or more, the requisite write voltage increases and writing becomes relatively difficult
Solution Approach 1:
The patent introduces a vertical dimension to the spin torque effect by utilizing spin-polarized current flowing perpendicular to the magnetic layer plane. This dimensional change in current flow direction enables more efficient coupling with the magnetic moment orientation, reducing the write voltage required for thicker magnetic layers compared to in-plane current configurations
Solution Approach 2:
The patent employs composite magnetic layer structures with specific material compositions and stacking sequences designed to enhance spin torque efficiency. By engineering the magnetic layer as a composite structure with tailored properties, the system achieves reduced write voltage requirements while maintaining the necessary magnetic characteristics for data storage
3Quantity of substance
If magnetic layer thickness is increased to about 20 nm-100 nm for horizontal magnetic recording, then storage capacity improves, but spin torque writing becomes relatively difficult
Solution Approach 1:
The patent changes the fundamental writing parameter from fringe field to spin torque, enabling effective writing in thicker magnetic layers (20-100 nm) that provide higher storage capacity. This parameter change allows the system to access thicker layers that were previously difficult to write with spin torque due to the inverse relationship between layer thickness and writing efficiency in conventional 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 approach enhances recording density, reduces power consumption, and improves reliability and thermal stability, enabling more efficient data storage with smaller current densities and higher storage capacity compared to conventional methods.
Implementation Method 1
a heating unit configured to heat a first region of a first magnetic layer
Implementation Method 2
a magnetic field applying unit configured to apply a magnetic field to the first region to form a magnetic domain
Implementation Method 3
A boundary portion between magnetic domains having different magnetization directions is referred to as a magnetic domain wall. Such magnetic domain walls have a given volume and may be moved by a current or an external magnetic field applied to a magnetic layer
Data Source
AI summary
Information storage devices using magnetic domain wall movement, methods of operating the same, and methods of manufacturing the same are provided. An information storage device includes a first magnetic layer, a heating unit and a magnetic field applying unit. The heating unit heats a first region of the first magnetic layer. The magnetic field applying unit applies a magnetic field to the first region to form a magnetic domain. A wall of the magnetic domain is moved by a current applied to the first magnetic layer.