Skyrmion Memory Element With Notch Geometry

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Solution Overview

Problem

Current magnetic shift registers require large currents and have low transfer speeds, making them inefficient for memory writing and erasing, and existing methods for generating and erasing skyrmions using steady-state currents lead to high power consumption and practical limitations in using skyrmions as non-volatile memory.

Innovation Solution

A magnetic element capable of generating and erasing a single skyrmion using pulse currents, with a chiral magnet structure and notch geometry, allowing for efficient skyrmion generation and erasure with low current density and short pulse durations, enabling high-speed memory operations without continuous power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If magnetic domain walls are driven using currents in a magnetic shift register, then magnetic information can be transferred, but large currents are required and transfer speed is low

Engineering Contradiction:
Improvetransfer speedVSAvoidcurrent consumption
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The patent changes the fundamental parameter being manipulated from magnetic domain walls to skyrmions. Skyrmions are topologically protected magnetic textures that can be moved with much lower current densities compared to domain walls, directly addressing both the speed and energy consumption issues. The skyrmion's topological stability allows for faster, more efficient transport with reduced current requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical movement of magnetic domain walls with the transport of skyrmions, which are stabilized by topological protection rather than simple domain boundary mechanics. This substitution enables more efficient current-driven transport with higher speeds and lower energy consumption, as skyrmions respond more effectively to spin-transfer torque.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If steady-state currents are used to generate and erase skyrmions, then skyrmions can be created, but a large number of skyrmions are generated and power consumption increases

Engineering Contradiction:
Improveskyrmion generation efficiencyVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic pulse currents instead of continuous steady-state currents to generate and erase skyrmions. By applying current pulses of specific duration and amplitude, skyrmions can be created and destroyed on demand with precise temporal control. This periodic action eliminates the need for continuous power supply, dramatically reducing power consumption while maintaining high generation efficiency.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent introduces dynamic control of skyrmion generation and erasure through time-varying current pulses. The system transitions from static skyrmion presence to dynamic creation and annihilation events, allowing skyrmions to be generated only when needed and erased to clear memory cells. This dynamic approach optimizes both productivity and energy efficiency by eliminating wasteful continuous operation.

Inventive Principle:
Principle #15Dynamics

3Reliability

If skyrmions are used as memory elements with steady-state currents, then information can be stored, but continuous power is required to maintain skyrmions

Engineering Contradiction:
Improvememory retentionVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent leverages the topological stability of skyrmions to enable self-maintained memory storage. Once skyrmions are generated through current pulses, they naturally persist without requiring continuous power supply to maintain their structure. The topological protection inherent to skyrmion configurations provides intrinsic stability, allowing the memory system to retain information passively without active power consumption, achieving non-volatile memory functionality.

Inventive Principle:
Principle #25Self-service

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 solution enables fast and low-power skyrmion memory operations, achieving high-speed data writing and erasure with minimal power consumption, potentially replacing traditional memory technologies like DRAM and SRAM.

Implementation Method 1

By making such proposals, the inventors of the present invention disclosed that skyrmions can be driven by currents

Methodology Applied
Scientific EffectSpin transfer torque:

Implementation Method 2

The magnetic change is detected by the magnetic sensor 2, which retrieves magnetic information

Methodology Applied
Scientific EffectMagnetic sensing:

Data Source

PatentEP3196944B1Magnetic element and skyrmion memory
Publication Date: 2021.05.05 RIKEN CO LTD
  • EP3196944B1 patent drawingFigure 1
  • EP3196944B1 patent drawingFigure 2(A)~2(E)
  • EP3196944B1 patent drawingFigure 3A

AI summary

Provided is a magnetic element capable of generating one skyrmion and erasing the one skyrmion. The magnetic element includes a magnet shaped like a substantially rectangular flat plate, an upstream electrode connected to the magnet in a width Wm direction of the magnet and made of a non-magnetic metal, a downstream electrode connected to the magnet in the width Wm direction to oppose the upstream electrode and made of a non-magnetic metal, and a skyrmion sensor configured to detect the skyrmion. Here, a width Wm of the substantially rectangular magnet is such that 3·λ > Wm ≥ λ, where λ denotes a diameter of the skyrmion, a length Hm of the substantially rectangular magnet is such that 2·λ > Hm ≥ λ, and the magnet has a notch structure at an edge between the upstream electrode and the downstream electrode.