Magnetic Racetrack Mesosurfaces via Reversible Ionic Liquid Gating

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Solution Overview

Problem

Existing methods for fabricating mesosurfaces, such as magnetic racetracks, are limited to planar surfaces, require irreversible modifications, and lack flexibility and dynamic adaptability, making them unsuitable for complex and smaller structures.

Innovation Solution

A method involving a substrate with reversible electron spin properties transitioned by a liquid that reacts with the substrate material to create mesosurfaces on curved or flexible surfaces, using ionic liquid gating to form magnetic racetracks without subtractive or additive steps, allowing for dynamic modifications and complex structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional lithographic patterning or micro-molding methods are used to fabricate mesosurfaces, then planar magnetic racetrack structures can be created, but the surfaces remain static and cannot be dynamically modified after fabrication

Engineering Contradiction:
Improvedynamic modification capabilityVSAvoidfixed geometrical parameters
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies the dynamics principle by using ionic liquid gating to enable reversible, dynamic modification of magnetic properties in mesosurfaces. The ionic liquid can be electrochemically oxidized or reduced to switch between different magnetic states (ferromagnetic, antiferromagnetic, paramagnetic), allowing the surface properties to change dynamically rather than remaining fixed after fabrication. This resolves the contradiction by making the previously static mesosurfaces adaptable and reconfigurable.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs parameter changes by utilizing electrochemical potential control to alter the magnetic properties of the mesosurface. By applying different voltages, the ionic liquid undergoes oxidation or reduction reactions that change the magnetic state of the underlying material. This allows dynamic tuning of magnetic parameters (such as magnetization direction and strength) without physically modifying the geometry, thereby achieving adaptability while maintaining structural stability.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If additive or subtractive fabrication processes are used to create mesosurfaces, then defined geometrical structures can be formed, but the manufacturing process becomes complex and irreversible

Engineering Contradiction:
Improvedefined geometrical parametersVSAvoidfabrication process steps
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the magnetic property definition from the physical geometry creation process. Instead of using complex additive or subtractive manufacturing to define both geometry and magnetic properties, the invention uses ionic liquid gating to extract and independently control magnetic properties through electrochemical reactions. This separates the geometric fabrication (which remains simple) from the magnetic property definition (which becomes dynamically controllable), thereby reducing overall device complexity while maintaining manufacturing precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The ionic liquid serves as an intermediary that mediates between the electrical control signal and the magnetic property modification. Rather than directly applying complex fabrication processes to define magnetic properties, the ionic liquid acts as a reversible mediator that can be electrochemically switched to induce desired magnetic states. This intermediary approach simplifies the fabrication process by replacing irreversible material deposition or removal with reversible electrochemical gating.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If conventional fabrication methods are used for mesosurfaces, then planar structures can be manufactured, but application to curved or flexible surfaces is excluded

Engineering Contradiction:
Improveapplication to non-planar surfacesVSAvoidfabrication method limitation
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent employs flexible thin films by demonstrating that the ionic liquid gating method can be applied to flexible substrates and curved surfaces. The electrochemical gating process does not require rigid planar geometry, allowing the mesosurface to be manufactured on flexible bases. This enables the magnetic racetrack structures to be conformally deposited on curved or flexible surfaces, expanding application versatility without complicating the fabrication method.

Inventive Principle:
Principle #30Flexible shells and thin films

4Manufacturing precision

If photolithography or electron-beam lithography with etching and deposition processes are used, then optical mesosurfaces can be fabricated, but the process requires multiple steps and causes irreversible material modifications

Engineering Contradiction:
Improvesurface pattern definitionVSAvoidnumber of fabrication process steps
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent merges multiple separate fabrication steps into a single integrated process. Instead of using photolithography followed by etching and then deposition (three separate steps), the ionic liquid gating method combines pattern definition and magnetic property modification into one simultaneous electrochemical process. The resist pattern defines the geometry while the ionic liquid gating simultaneously establishes the magnetic properties, thereby reducing the number of fabrication steps and saving time.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent applies preliminary action by pre-forming the geometric pattern using a simple resist mask before applying the ionic liquid. This preliminary geometric definition allows the subsequent electrochemical gating to focus solely on magnetic property modification without requiring complex in-situ pattern formation. The resist pattern is prepared in advance, and then the ionic liquid is applied to define magnetic properties, separating the geometric and magnetic definition steps while reducing overall process complexity.

Inventive Principle:
Principle #10Preliminary action

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

Enables the creation of dynamic, flexible mesosurfaces with tunable magnetic properties on non-planar surfaces, facilitating efficient movement of domain walls and enabling applications in spin ice, magnetic logic, and neuromorphic computing.

Implementation Method 1

a liquid which reacts with the substrate material to yield in or to bring about the transition into the at least one second state of the electron spin property

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

a substrate which exhibits at least two distinct measurable states of an electron spin property and which can stably but reversibly be transitioned from a first state of the electron spin property into at least one second state

Methodology Applied
Scientific EffectElectron spin transition: Magnetism

Data Source

PatentEP4009388B1Method for making mesosurfaces for magnetic racetracks
Publication Date: 2025.07.02 MAX PLANCK GESELLSCHAFT ZUR FOERDERUNG DER WISSENSCHAFTEN EV
  • EP4009388B1 patent drawingFigure 1a~1f
  • EP4009388B1 patent drawingFigure 3a~3g
  • EP4009388B1 patent drawingFigure 4a~4g

AI summary

A method of making mesosurfaces, allowing for realising smaller and more complex structures and for a dynamic reversible modification thereof, comprises contacting a defined and delineated surface area of a substrate with a liquid which reacts with the substrate material to bring about a transition between at least two stable states of an electron spin property within the area only, in particular by local ionic liquid gating between insulating antiferromagnetic SrCoO2.5 and metallic ferromagnetic SrCoO3.