Terahertz Spin-Torque Nano Oscillator With Low Current Threshold
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Solution Overview
Problem
Conventional nano-oscillating devices using spin Hall spin torque and antiferromagnetic materials require high current density and have limited frequency tunability, necessitating a device that can oscillate at low current density with improved frequency adjustability.
Innovation Solution
A magnetic nano-oscillating device is designed with a stacked structure of a ferromagnetic layer, a nonmagnetic conductive layer, and an antiferromagnetic or ferrimagnetic layer, where in-plane current is applied to generate spin current, inducing magnetization precession in the antiferromagnetic or ferrimagnetic layer, thereby reducing current density and enhancing frequency tunability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spin Hall spin torque and antiferromagnetic material are used to induce precession motion, then magnetization precession can be achieved, but significantly high current density is required
Solution Approach 1:
The patent changes the magnetization orientation parameter from in-plane to perpendicular magnetization in the ferromagnetic layer, which fundamentally alters the spin torque mechanism and reduces the current density threshold for magnetization precession from significantly high levels to much lower operational levels
Solution Approach 2:
The patent employs a composite stacked structure consisting of ferromagnetic layer, nonmagnetic layer, and antiferromagnetic layer, where the interaction between these different materials creates an efficient spin torque mechanism that reduces the current density requirement compared to using antiferromagnetic material alone
2Reliability
If conventional spin Hall spin torque method is used, then magnetization precession can be induced, but frequency tunability is limited
Solution Approach 1:
The patent introduces dynamic controllability by applying in-plane current to the ferromagnetic layer, which enables real-time tuning of the precession frequency through current magnitude control, transforming the system from a fixed-frequency to a dynamically adjustable frequency oscillator
Solution Approach 2:
The patent utilizes the ability to change the current density parameter applied to the ferromagnetic layer to continuously tune the precession frequency across a wide range, achieving superior frequency tunability compared to conventional methods
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 device achieves low current density operation and improved frequency tunability by generating spin-polarized spin current that induces interfacial spin-orbit torque, allowing for magnetization precession in the antiferromagnetic or ferrimagnetic layer, enabling oscillation in the 0.1 THz to 10 THz range with reduced threshold current density.
Implementation Method 1
An up-spin electron and a down-spin electron are polarized in opposite directions due to spin-orbit coupling. Thus, spin current is generated in a z direction perpendicular to a direction of externally applied current direction
Implementation Method 2
When the spin element flows into an adjacent ferromagnetic material, the ferromagnetic material receives a spin transfer torque. Such a torque is called a spin Hall spin torque
Implementation Method 3
spin current, including a spin in a thickness direction of a thin film transferred to the antiferromagnetic layer, to cause magnetization precession of a sub-lattice of the antiferromagnetic layer
Data Source
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AI summary
A magnetic nano oscillating device, according to an embodiment of the present invention, comprises: a ferromagnetic layer disposed on a substrate; a non-magnetic conductive layer laminated on the ferromagnetic layer; an antiferromagnetic layer (or a ferrimagnetic layer) laminated on the non-magnetic conductive layer; and first and second electrodes respectively contacting both side surfaces of the ferromagnetic layer and the non-magnetic conductive layer. The antiferromagnetic layer (or ferrimagnetic layer) is a thin film made of a material magnetized in perpendicular or in-plane to a layer surface, the ferromagnetic layer is magnetized in-plane to a layer surface of the ferromagnetic layer, and an in-plane current injected into the ferromagnetic layer and the non-magnetic conductive layer through the first and second electrodes provides a spin current including a spin in a thickness direction of the thin film transferred to the antiferromagnetic layer (or ferrimagnetic layer), thereby causing magnetization precessional motion of a sub-lattice of the antiferromagnetic layer (or ferrimagnetic layer).