MLU Magnetic Sensor Stress-Induced Anisotropy Programming
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Solution Overview
Problem
Conventional MLU-based magnetic sensor devices can only orient the storage magnetization in one direction, limiting their programming flexibility and sensitivity, especially when trying to sense external magnetic fields with multiple orientations, as the programming magnetic field required for non-axial orientations is insufficient.
Innovation Solution
Incorporating a stress-inducing device to apply anisotropic mechanical stress on the magnetic tunnel junction, inducing stress-induced magnetic anisotropy in the sense and storage layers, allowing for independent orientation of magnetization in each branch, thereby improving programming and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sense layer magnetization is oriented perpendicular to the storage magnetization using conventional sputter conditions, then linear and non-hysteretic behavior is achieved, but only one sensing direction is available
Solution Approach 1:
The patent applies different stress conditions to different regions or configurations of the magnetic tunnel junction to create locally optimized magnetic anisotropy. By introducing stress inducing devices that apply specific mechanical stress to particular MLU cells or branches, the sense layer magnetization can be oriented in different directions while maintaining linear and non-hysteretic behavior, thus enabling multi-directional sensing capability
Solution Approach 2:
The patent transitions from relying solely on in-plane magnetization orientation to utilizing out-of-plane stress-induced magnetization orientation. By applying mechanical stress perpendicular to the film plane, the sense layer magnetization can be oriented in directions not achievable through conventional in-plane sputter conditions alone, adding a new dimension to the sensing capability
2Adaptability or versatility
If the storage magnetization is programmed in a direction far from the intrinsic anisotropy axis, then multi-directional sensing is enabled, but the programming magnetic field becomes insufficient
Solution Approach 1:
The patent changes the physical state or parameters of the magnetic layers by introducing mechanical stress. This stress modifies the magnetic anisotropy energy landscape, creating new easy axes of magnetization that align with the desired programming directions. Consequently, the storage magnetization can be programmed in directions far from the intrinsic anisotropy axis using reduced magnetic field strength
Solution Approach 2:
The patent introduces stress inducing devices as intermediary elements between the programming system and the magnetic tunnel junction. These devices convert mechanical stress into modified magnetic anisotropy, which then facilitates easier programming of the storage magnetization in desired directions without requiring excessively strong magnetic fields
3Ease of manufacture
If a single anisotropy direction is defined by fabrication conditions, then manufacturing is simplified, but programming flexibility is limited
Solution Approach 1:
The patent segments the magnetic sensor device into multiple branches or regions, each with its own stress inducing device that can be independently controlled. This allows different segments to have different stress-induced anisotropy directions, enabling flexible programming of multiple sensing directions while maintaining a relatively simple base fabrication process
Solution Approach 2:
The patent introduces dynamically adjustable stress conditions through controllable stress inducing devices. The stress magnitude and direction can be adjusted during operation to reprogram the magnetic anisotropy axes, providing programming flexibility without requiring complex multi-step fabrication processes for each configuration
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
This approach enables each branch of the magnetic sensor device to be easily programmed and sensitive to external magnetic fields, ensuring linear and non-hysteretic behavior, enhancing the device's ability to accurately measure magnetic field directions.
Implementation Method 1
a stress inducing device configured for applying an anisotropic mechanical stress on the magnetic tunnel junction such as to induce a stress-induced magnetic anisotropy on at least one of the sense layer and the storage layer
Implementation Method 2
The external magnetic field can thus be sensed by measuring a resistance of the magnetic tunnel junction that depends on the relative orientation of the sense magnetization, oriented by the external magnetic field, and the storage magnetization
Data Source
AI summary
A magnetic sensor device for sensing an external magnetic field includes a plurality of MLU cells, each MLU cell having a magnetic tunnel junction including a sense layer having a sense magnetization freely orientable in the external magnetic field, a storage layer having a storage magnetization; and a tunnel barrier layer between the sense layer and the storage layer. The magnetic sensor device includes a stress inducing device configured for applying an anisotropic mechanical stress on the magnetic tunnel junction such as to induce a stress-induced magnetic anisotropy on at least one of the sense layer and the storage layer. The stress-induced magnetic anisotropy induced by the stress inducing device corresponds substantially to a net magnetic anisotropy of the at least one of the sense layer and the storage layer. The magnetic sensor device can be programmed easily and has improved sensitivity.