Nonvolatile Magnetic Logic Array Switching Reliability
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Solution Overview
Problem
Conventional nonvolatile logic devices using magnetic junctions face reliability issues due to sensitivity to external magnetic fields, requiring precise control for switching, and are prone to inadvertent writing when using magnetic fields for state changes.
Innovation Solution
A nonvolatile logic device design that includes an input magnetic junction and an output magnetic junction, magnetically coupled through intermediate junctions, allowing switching via spin transfer torque and external magnetic fields applied along hard axes, with a magnetic field removal mechanism to stabilize the output state, reducing the need for precise field control and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external magnetic field is applied to switch magnetic junctions, then the state of the output junction can be changed, but the timing and precision of field application must be tightly controlled to prevent inadvertent writing
Solution Approach 1:
The patent segments the magnetic junction array into distinct functional groups: input junctions, intermediate junctions, and output junctions. Each group has a specific role in the logic operation, allowing the system to process information through a structured sequence of magnetic state changes without requiring precise control of the entire array simultaneously.
Solution Approach 2:
The patent introduces intermediate junctions as mediators between input and output junctions. These intermediate junctions receive magnetic fields from input junctions and transfer the magnetic state information to output junctions, decoupling the control requirements and allowing more relaxed timing for field application.
2Reliability
If a strong external magnetic field is applied to ensure saturation of magnetic junctions, then switching is more reliable, but the input magnetic junction state may be inadvertently changed
Solution Approach 1:
The patent applies local quality by giving different magnetic anisotropy orientations to different junction groups. Input junctions have their easy axis perpendicular to the plane, while intermediate and output junctions have in-plane easy axes. This local differentiation allows strong fields to saturate intermediate/output junctions without affecting input junctions.
Solution Approach 2:
The patent implements preliminary action by having input junctions switch their state first through spin transfer torque, generating the magnetic field that saturates intermediate and output junctions. This sequence ensures that by the time strong fields are applied, the input junctions have already established their intended state.
3Measurement precision
If the external magnetic field application time is tightly controlled, then switching precision is improved, but the complexity of control increases
Solution Approach 1:
The patent implements self-service by designing the magnetic junctions to automatically saturate and stabilize at their equilibrium states once the external field is applied. The magnetic moments naturally align with the field and remain stable without requiring continuous control or precise timing, allowing the system to self-regulate the field application duration.
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 design improves the reliability and ease of programming by allowing a wider range of external magnetic fields for saturation, reducing inadvertent writing, and ensuring stable state transitions, thus enhancing the performance of nonvolatile logic devices.
Implementation Method 1
The input magnetic junction may be switchable using a current driven through the magnetic junction
Implementation Method 2
an appropriate external magnetic field that saturates the magnetic junctions 14, 16, 18, 20, and 22 along their hard axes is applied. The result is that the magnetic moments of the junctions 14, 16, 18, 20, and 22 are aligned with the saturation field along the hard axis
Implementation Method 3
The magnetic junctions 12, 14, 16, 18, 20, and 22 are typically tunneling magnetoresistive junctions
Data Source
AI summary
A method and system provide and program a nonvolatile logic device. The nonvolatile logic device includes input and output magnetic junctions and at least one magnetic junction between the input and output magnetic junctions. The input magnetic junction includes an input junction free layer having an input junction easy axis. The input magnetic junction may be switchable using a current driven through the magnetic junction. The output magnetic junction includes an output junction free layer having an output junction easy axis. Each of the magnetic junction(s) includes a free layer having an easy axis. The input magnetic junction is magnetically coupled to the output magnetic junction through the magnetic junction(s). In some aspects, the method includes switching the magnetic moment(s) of the input magnetic junction from a first state to a second state, applying and then removing magnetic field(s) along the hard axis of the at least one magnetic junction.