Spin-Orbit Torque Magnetization Element for Stable Data Storage
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Solution Overview
Problem
The integration of spin-current magnetization rotational elements in integrated circuits is hindered by the need for external magnetic fields, which can cause unintended magnetization reversals due to external forces, leading to data noise and instability in long-term storage.
Innovation Solution
A spin-current magnetization rotational element is designed without an external magnetic field, utilizing shape anisotropy to generate a demagnetizing field that facilitates magnetization reversal through spin-orbit torque, with a ferromagnetic metal layer and spin-orbit torque wiring intersecting in a specific configuration to control magnetization direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an external magnetic field is applied to reverse magnetization, then magnetization reversal can be achieved, but the degree of integration of the integrated circuit decreases due to the need for separate magnetic field sources
Solution Approach 1:
The invention extracts the magnetic field generation function from the main device structure by utilizing the spin-orbit torque wiring to generate spin current that indirectly produces the necessary magnetic field effect through spin transfer torque, eliminating the need for separate magnetic field sources and enabling higher integration
Solution Approach 2:
The spin-orbit torque wiring acts as an intermediary that converts electrical current into spin current, which then exerts torque on the ferromagnetic layer to reverse magnetization without requiring direct magnetic field application, thus maintaining integration while achieving magnetization reversal
2Ease of operation
If an external magnetic field is used for magnetization reversal, then data writing can be performed, but unintended magnetization reversals occur due to external forces causing data noise
Solution Approach 1:
The device uses its own spin-orbit torque wiring to generate the spin current necessary for magnetization reversal, making the system self-contained and immune to external magnetic field interference, thus improving data storage reliability while maintaining writing capability
Solution Approach 2:
The spin-orbit torque mechanism creates a controlled magnetization reversal process that counteracts the vulnerability to external magnetic fields, preventing unintended reversals before they can occur by establishing a more robust, internally-controlled switching mechanism
3Productivity
If a high reversing current density is applied to reverse magnetization in a TMR element, then magnetization reversal can be achieved, but the life span of the TMR element decreases
Solution Approach 1:
The spin-orbit torque wiring serves as an intermediary that generates spin current to reverse magnetization, allowing the current to flow outside the TMR element rather than through it, thus achieving magnetization reversal while preserving the element's longevity
Solution Approach 2:
The invention separates the current path for magnetization reversal from the TMR element structure itself by using a dedicated spin-orbit torque wiring layer, so that the high current required for reversal does not pass through the delicate TMR stack, protecting it from degradation
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 allows for reliable magnetization reversal without external magnetic fields, enhancing data storage stability and reducing noise, thereby improving the integration and longevity of spin-current magnetization rotational elements in integrated circuits.
Implementation Method 1
magnetization reversal using a net spin current which is generated by a spin-orbit interaction has attracted attention as means for decreasing a reversing current
Implementation Method 2
A net spin current which is generated by the spin-orbit interaction induces a spin orbit torque (SOT) and causes magnetization reversal due to the SOT
Implementation Method 3
the ferromagnetic metal layer has shape anisotropy and has a demagnetizing field distribution caused by the shape anisotropy
Implementation Method 4
A giant magnetoresistance (GMR) element including a multilayered film of a ferromagnetic layer and a nonmagnetic layer
Implementation Method 5
tunneling magnetoresistance (TMR) element using an insulating layer (a tunnel barrier layer, a barrier layer) as a nonmagnetic layer
Data Source
AI summary
A spin-current magnetization rotational element includes: a ferromagnetic metal layer; and a spin-orbit torque wiring that extends in a first direction intersecting a stacking direction of the ferromagnetic metal layer and is bonded to the ferromagnetic metal layer. A direction of a spin injected into the ferromagnetic metal layer from the spin-orbit torque wiring intersects a magnetization direction of the ferromagnetic metal layer. The ferromagnetic metal layer has shape anisotropy and has a demagnetizing field distribution caused by the shape anisotropy. The demagnetizing field distribution generates an easy magnetization rotational direction in which the magnetization of the ferromagnetic metal layer is most easily reversed. The easy magnetization rotational direction intersects the first direction in a plan view seen from the stacking direction.