Magnetic Oscillation Element Frequency Stabilization
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Solution Overview
Problem
Current magnetic oscillation elements fail to achieve stable oscillation frequency while maintaining high output and low current density, essential for applications like wireless communication and magnetic recording/playback, due to limitations in element resistance and MR ratio.
Innovation Solution
A magnetic oscillation element with a magnetic free layer and pinned layer, where the magnetization directions are controlled within specific angles and an external magnetic field is applied to cancel frequency shifts caused by diamagnetic and uniaxial magnetic anisotropy fields, allowing for stable oscillation at a current density below 1.0×10^7 A/cm².
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If element resistance is increased to about 100Ω for efficient high-frequency extraction, then high-frequency output extraction is improved, but current density increases beyond the acceptable threshold
Solution Approach 1:
The patent changes the magnetization orientation parameter from in-plane to perpendicular magnetization, which fundamentally alters the magnetic oscillation characteristics. This parameter change enables the element to achieve stable oscillation at lower current densities while maintaining high-frequency output capability, resolving the contradiction between power output and energy consumption.
Solution Approach 2:
The patent introduces local quality by creating specific magnetic anisotropy conditions in different layers. The perpendicular magnetization is achieved through controlled magnetic anisotropy in the ferromagnetic layer, allowing localized magnetic properties to be optimized for both low current density operation and high-frequency output extraction.
2Power
If MR ratio is increased to achieve high output, then output power is improved, but element resistance increases causing higher current density
Solution Approach 1:
The patent changes the fundamental parameter of magnetization orientation to perpendicular magnetization, which decouples the relationship between MR ratio and element resistance. This allows the element to achieve high output power through enhanced magnetic oscillation amplitude rather than through increased resistance, thereby avoiding the penalty of higher current density.
3Adaptability or versatility
If oscillation frequency is increased for high-frequency applications, then application versatility is improved, but frequency stability deteriorates due to diamagnetic field shifts
Solution Approach 1:
The patent converts the harmful diamagnetic field effect into a beneficial stabilization mechanism. By operating in the perpendicular magnetization regime, the diamagnetic field shift is suppressed and can even contribute to stabilizing the oscillation frequency, thereby resolving the contradiction between frequency versatility and stability.
Solution Approach 2:
The patent changes the magnetization orientation parameter to perpendicular magnetization, which fundamentally alters the response to diamagnetic fields. This parameter change suppresses the frequency shift caused by diamagnetic fields, enabling stable oscillation across a wide frequency range suitable for various high-frequency applications.
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 stabilizes the oscillation frequency, enabling high output and long service life while maintaining low current density, thus addressing the limitations of existing elements.
Implementation Method 1
when DC current I larger than certain threshold current IC is supplied to a magnetoresistive effect element (MR element) such as a GMR element or IMR element, a spin torque acts on a free layer magnetization in the MR element, thus exciting a steady magnetization oscillation
Implementation Method 2
This magnetization oscillation is converted into a high-frequency power by an MR effect
Implementation Method 3
an external magnetic field is applied to cancel frequency shifts caused by diamagnetic and uniaxial magnetic anisotropy fields
Implementation Method 4
frequency shifts caused by diamagnetic and uniaxial magnetic anisotropy fields
Implementation Method 5
frequency shifts caused by diamagnetic and uniaxial magnetic anisotropy fields
Data Source
AI summary
According to one embodiment, magnetization directions of a magnetic free layer and a magnetic pinned layer are parallel to junction planes between the magnetic free layer and a spacer layer and between the magnetic pinned layer and the spacer layer. The magnetic free layer has a uniaxial magnetic anisotropy, and generates a magnetization oscillation when a current larger than an oscillation threshold current flows through the magnetic free layer. A magnetic field generator controls a magnitude and a direction of an external magnetic field to cancel a shift amount of an oscillation frequency caused by a diamagnetic field due to the magnetization oscillation and a shift amount of the oscillation frequency caused by a magnetic field due to the uniaxial magnetic anisotropy.