Laminated Spin Element Wiring for Temperature-Stable SOT Memory
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Solution Overview
Problem
Spin elements using spin-orbit torque (SOT) face instability due to temperature-dependent magnetic anisotropy energy and resistivity changes, affecting their operation across a wide temperature range, particularly in spin-orbit-torque magnetization rotational elements and magnetic domain wall displacement type magnetic recording elements.
Innovation Solution
A lamination structure in the current-carrying part comprising a first wiring and a second wiring, where the first wiring has a larger temperature dependence of resistivity than the second wiring, allowing for adjusted current distribution across different temperature ranges, thereby stabilizing the spin element's operation. The first wiring can be a metal, semiconductor, or topological insulator, while the second wiring is a semiconductor or topological insulator, optimizing the spin-orbit interaction and reducing temperature dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single wiring is used in the current-carrying part, then the structure is simple, but the operation stability changes significantly with temperature
Solution Approach 1:
The current-carrying part is segmented into multiple wirings (first wiring and second wiring) with different materials and temperature-dependent resistivity characteristics. This segmentation allows each wiring to contribute differently to current flow at various temperatures, stabilizing the overall operation of the spin element across a wide temperature range.
Solution Approach 2:
The invention uses composite material structure in the current-carrying part, combining wirings made of different materials (e.g., metal and semiconductor, or different metal alloys) that have complementary temperature-dependent electrical properties. This composite approach enables the current distribution to self-adjust with temperature changes, improving reliability without significantly increasing structural complexity.
2Reliability
If temperature compensation is implemented using traditional methods (thermometers, voltage control units), then operation stability improves, but device complexity increases
Solution Approach 1:
The spin element achieves temperature compensation through self-service mechanism. The multiple wirings with different temperature-dependent resistivities automatically adjust their current distribution in response to temperature changes, eliminating the need for external thermometers or voltage control units. The system compensates for its own temperature variations inherently.
Solution Approach 2:
The invention exploits parameter changes in the electrical resistivity of different materials with temperature. By selecting wirings with specific resistivity-temperature characteristics, the system naturally maintains stable operation across temperature ranges without requiring additional control mechanisms, thus avoiding increased device complexity.
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 solution reduces temperature dependence, enabling stable operation of spin elements across a wide temperature range without the need for thermometers or voltage control units, thus allowing for compact and efficient spin memory devices.
Implementation Method 1
both of the first wiring and the second wiring are metals and temperature dependence of resistivity of the first wiring is larger than temperature dependence of resistivity of the second wiring
Implementation Method 2
the current-carrying part may be a spin-orbit torque wiring configured to apply a spin-orbit torque to a magnetization of the first ferromagnetic layer so as to rotate the magnetization
Data Source
AI summary
This spin element includes: a current-carrying part that extends in a first direction; and an element part that is laminated on one surface of the current-carrying part, wherein the current-carrying part includes a first wiring and a second wiring in order from a side of the element part, and wherein both of the first wiring and the second wiring are metals and temperature dependence of resistivity of the first wiring is larger than temperature dependence of resistivity of the second wiring in at least a temperature range of −40° C. to 100° C.