Ferromagnetic Memory Cell with Anisotropy Gradient for Multilevel Storage

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Solution Overview

Problem

Existing spin-transfer torque magnetoresistive random-access memory (STT-MRAM) devices struggle to implement multiple levels of data storage due to limitations in controlling magnetization states within a single transistor and magnetic tunnel junction (MTJ).

Innovation Solution

A ferromagnetic memory device is developed with a magnetic anisotropy energy gradient induced by plasma ion irradiation, forming multiple magnetic domains within the magnetic free layer, allowing control of magnetization states through adjustable input current pulses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single transistor and magnetic tunnel junction (MTJ) are used in STT-MRAM, then the device structure is simple, but multiple levels of data storage cannot be implemented

Engineering Contradiction:

Improvemulti-level data storage capabilityVSAvoiddevice structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The magnetic free layer is segmented into multiple magnetic domains with different magnetization states. By dividing the single magnetic layer into multiple domains that can be independently controlled, the device achieves multi-level storage capability without adding separate storage elements, thus resolving the contradiction between versatility and complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the magnetic free layer are given different local properties through plasma ion irradiation, creating zones with different magnetic anisotropy energies. This allows each region to represent different data levels, enabling multi-level storage while maintaining a unified device structure.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If plasma ion irradiation is used to create magnetic anisotropy energy gradient, then magnetic domains can be formed, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvemagnetic domain formation precisionVSAvoidmanufacturing process simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The plasma ion irradiation process changes the magnetic anisotropy energy parameter of the magnetic layer by controlling ion energy, dose, and distribution. By adjusting these parameters, precise control over magnetic domain formation is achieved, enabling high manufacturing precision while using a relatively simple process addition.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If magnetic anisotropy energy gradient is induced by plasma ion irradiation, then multiple magnetic domains are formed, but the device operates at higher current requirements

Engineering Contradiction:

Improvemagnetization state control flexibilityVSAvoidinput current consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the input current magnitude and pulse duration to selectively switch between different magnetic domains. By making the current control adaptive rather than fixed, the device can achieve flexible multi-level magnetization state control while minimizing energy consumption by applying only the necessary current for the desired transition.

Inventive Principle:

Principle #15Dynamics

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 multi-level data storage by manipulating magnetization states in the ferromagnetic memory device, enhancing data storage capacity and efficiency.

Implementation Method 1

a magnetic anisotropy energy gradient induced within the magnetic layer by plasma ion irradiation

Methodology Applied

Scientific EffectMagnetic anisotropy: Anisotropy

Implementation Method 2

induced by plasma ion irradiation

Methodology Applied

Scientific EffectPlasma ion irradiation: Plasma

Implementation Method 3

when ions are injected into the magnetic free layer

Methodology Applied

Scientific EffectIon implantation: Ion Implantation

Implementation Method 4

spin-transfer torque magnetoresistive random-access memory (STT-MRAM)

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 5

magnetic tunnel junction (MTJ) formed by inserting a thin insulating layer between two ferromagnetic layers

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Implementation Method 6

Ferromagnetic materials are easily magnetized and maintain their magnetization states even after an external magnetic field is removed

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentUS20260032919A1Ferromagnetic memory device for operating at multilevel, method for manufacturing the same, and sysytem including the same

Publication Date: 2026.01.29 UI (UNIVERSITY IND FOUNDATION) YONSEI UNIVERSITY

AI summary

A ferromagnetic memory device comprises a memory cell. wherein the memory cell includes a magnetic free layer including a magnetic layer, and wherein the magnetic free layer including a magnetic anisotropy energy gradient induced within the magnetic layer by plasma ion irradiation.