Race-track Memory Domain Wall Stabilization via Spin Orbital Torque
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Solution Overview
Problem
Spintronics-based magnetic memory with race-track nanowires faces challenges in achieving consistent domain wall pinning, leading to incorrect data transfer and corruption due to varying notch sizes and difficulty in distinguishing between single and multiple bits.
Innovation Solution
A memory system utilizing a spin orbital torque block and magnetic tunnel junction stacks to read and write data, eliminating the need for domain wall pinning and ensuring uniform cross-sections, with magnetic domains and domain walls aligned to enhance data separation and storage density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If domain wall pinning is used to store data in magnetic domains, then data storage is enabled, but manufacturing precision deteriorates due to difficulty in making all notches identical
Solution Approach 1:
The patent removes the notch structure entirely from the magnetic nanowire, extracting the problematic pinning mechanism that required precise manufacturing. Instead of using notches to pin domain walls, the invention uses the natural magnetic anisotropy and domain wall interactions with the wire geometry, eliminating the manufacturing precision requirement while maintaining data storage functionality.
Solution Approach 2:
The patent changes the fundamental parameter from mechanical pinning (notches) to magnetic pinning (anisotropy and domain wall energy minimization). This parameter change allows domain walls to be stabilized without requiring precise geometric features, resolving the contradiction between reliability and manufacturing precision.
2Reliability
If notches of varying cross-sections are used in the nanowire, then domain wall pinning is achieved, but speed uniformity deteriorates causing data corruption
Solution Approach 1:
The patent employs a uniform nanowire cross-section throughout, eliminating the heterogeneous notch structures that caused varying domain wall speeds. This homogeneity ensures that all domain walls experience identical conditions and move at uniform speeds, preventing data corruption while maintaining reliable pinning through magnetic rather than geometric means.
3Quantity of substance
If magnetic domains with same polarity are placed adjacent to each other, then storage density is improved, but measurement precision deteriorates making bit distinction difficult
Solution Approach 1:
The patent introduces domain walls as intermediary structures between magnetic domains of the same polarity. These domain walls serve as detectable markers that allow distinction between adjacent bits even when the domains themselves have identical polarities. The domain walls create local magnetic field variations that can be detected, enabling precise bit identification while maintaining high storage density through same-polarity domain placement.
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
Achieves clear bit-to-bit separation, improves storage density, and reduces errors by stabilizing domain wall movement and flux closure, making data reading and writing more reliable and efficient.
Implementation Method 1
a spin orbital torque block overlapping the memory track at an overlap region and extending in a direction perpendicular to an extension direction of the memory track, the SOT block being configured to induce a magnetization in the overlap region of the memory track when a charge current passes through the SOT block
Implementation Method 2
magnetic tunnel junction stacks to read and write information to a race-track memory
Data Source
AI summary
A memory system includes a memory track including a plurality of magnetic domains having alternating magnetic polarities and positioned along a path, and a plurality of domain walls separating adjacent ones of the plurality of magnetic domains, each one of the domain walls being configured to store data.