Three-Terminal Non-Local Spin Valve for Thin Magnetic Sensors
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Solution Overview
Problem
Current spin valve elements face challenges in reducing thickness to accommodate high-density magnetic recording, as the antiferromagnetic layer required for magnetization pinning limits the overall thickness, and the presence of multiple external lead terminals complicates manufacturing and increases noise susceptibility.
Innovation Solution
A three-terminal non-local spin valve element design with a nonmagnetic base layer and separate spin injection and detection terminals, where the ground terminal is shared between the current source and voltmeter, allowing for reduced nonmagnetic base electrode length and improved spin accumulation, while minimizing external lead terminal influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a four-layer spin valve structure with antiferromagnetic layer is used to achieve magnetization pinning, then magnetization-pinning characteristics are improved, but the thickness of the magnetic sensor cannot be reduced to 10 nm or less
Solution Approach 1:
The patent extracts and removes the antiferromagnetic layer from the traditional four-layer spin valve structure, creating a novel three-terminal non-local spin valve element that achieves magnetization pinning through alternative mechanisms, thereby enabling the magnetic sensor thickness to be reduced to 10 nm or less while maintaining pinning characteristics
Solution Approach 2:
The patent transitions from a vertical four-layer stack structure to a three-terminal non-local configuration where spin injection and detection occur through lateral separation, fundamentally changing the dimensional arrangement to achieve both thinness and functional performance
2Ease of operation
If multiple external lead terminals are used in spin valve elements, then electrical connections are established, but manufacturing complexity increases and noise susceptibility increases
Solution Approach 1:
The patent merges the ground terminal functions by sharing a common ground terminal between the current source and voltmeter in the three-terminal configuration, reducing the number of external lead terminals required and thereby simplifying manufacturing while maintaining electrical connection functionality
Solution Approach 2:
The ground terminal serves multiple functions simultaneously by being shared between the current source and voltmeter, allowing a single terminal to fulfill multiple electrical connection roles and reducing overall terminal count and manufacturing 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
This design enables a thinner, more sensitive magnetic sensor for high-density hard disk heads with reduced noise and manufacturing complexity, maintaining high signal-to-noise ratio and output voltage.
Implementation Method 1
a spin injection magnetic member, a spin detection magnetic member which are electrically connected to a nonmagnetic base electrode
Implementation Method 2
improved spin accumulation
Implementation Method 3
a spin detection magnetic member which are electrically connected to a nonmagnetic base electrode
Implementation Method 4
an antiferromagnetic layer which is disposed on the magnetic layer and pins a magnetization direction of the magnetic layer
Data Source
AI summary
A spin valve element according to an embodiment includes: a nonmagnetic base layer; a first terminal including a first magnetic layer connecting to a portion near one of opposing end faces of the nonmagnetic base layer; a second terminal including a second magnetic layer disposed and connecting to the nonmagnetic base layer so as to be at a distance from the first terminal; a third terminal including a third magnetic layer disposed and connecting to the nonmagnetic base layer so as to be at distances from the first and second terminals, the second terminal and the third terminal connecting to a current source that passes a sense current, and the first terminal and one of the second terminal and the third terminal connecting to a voltage detection unit that detects a voltage.