Spin-Valve Element with Peripheral Cutouts for Magnetization Control
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Solution Overview
Problem
Existing spin-valve recording elements face challenges in achieving high recording density and efficient multivalue recording due to the need for complex structures and increased magnetic fields, which hinder practical application in solid-state magnetic memory devices.
Innovation Solution
A spin-valve element with a circular in-plane shape and peripheral cutouts, where the coercive forces of the ferromagnetic layers are different, allowing for reduced shape anisotropy and lower magnetic fields required for recording, enabling stable vortex-shape magnetization and multivalue recording without multiple structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If complex multiple structures are used for multivalue recording, then recording capacity increases, but device complexity increases
Solution Approach 1:
The invention divides the magnetic recording element into distinct functional layers (free layer, pinned layer, nonmagnetic layer) with specific coercive force characteristics. Each layer is segmented to perform a specific function: the free layer with lower coercive force responds to write fields, while the pinned layer with higher coercive force maintains stable magnetization, enabling multivalue recording through controlled magnetization states without requiring complex multiple structures
Solution Approach 2:
The invention applies local quality by giving different coercive force characteristics to different layers. The free layer is designed with lower coercive force to be easily switched, while the pinned layer has higher coercive force for stability. This local differentiation of magnetic properties enables the system to achieve multivalue recording capability through controlled magnetization reversal in specific regions rather than requiring complex overall structures
2Reliability
If increased magnetic fields are applied for recording, then magnetization reversal reliability improves, but energy consumption increases
Solution Approach 1:
The invention changes the magnetic field parameter distribution by creating a gradient through the layered structure. The write magnetic field is concentrated in the free layer with lower coercive force, enabling reliable magnetization reversal at reduced field strengths. The pinned layer with higher coercive force acts as a barrier that prevents excessive field penetration, thereby reducing overall energy consumption while maintaining reversal reliability in the free layer
3Speed
If larger magnetization reversal current is used, then switching speed improves, but energy consumption increases
Solution Approach 1:
The invention optimizes the current parameter by leveraging the lower coercive force of the free layer. Spin-polarized current from the pinned layer efficiently transfers angular momentum to the free layer magnetization, enabling fast reversal at lower current densities. The differential coercive force parameters between layers create a more efficient spin transfer torque mechanism, achieving high-speed switching with reduced energy input
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 configuration enables high recording density and faster magnetization reversal with reduced magnetization reversal current, allowing for efficient multivalue recording using a simpler structure and single-polarity current, while maintaining low energy states.
Implementation Method 1
The magnetization of the free layer 25 is controlled by spin injection by an external magnetic field or by a spin-polarized current
Implementation Method 2
Control by spin injection, when electrons are passed to this element from the fixed layer 23, a torque acts so as to make the spin of the free layer 25 parallel to that of the fixed layer 23
Implementation Method 3
spin-valve elements which apply the tunneling magnetoresistance (TMR) effect occurring in a layered structure of a ferromagnetic layer/insulating layer/ferromagnetic layer
Implementation Method 4
the giant magnetoresistance (GMR) effect occurring in a layered structure of a ferromagnetic layer/nonmagnetic layer (conductive layer)/ferromagnetic layer
Implementation Method 5
The magnetization of the fixed layer 23 is fixed by magnetic coupling with the antiferromagnetic layer 22
Data Source
AI summary
A spin-valve element has a pair of ferromagnetic layers having mutually different coercive forces, sandwiching an insulating layer or a nonmagnetic layer therebetween. The in-plane shape of the spin-valve element is substantially circular in shape but is provided, in the peripheral portion, with a plurality of cutouts NS, NW, NE, NN. Preferably, the shape of at least one cutout be made different from that of others. Moreover, a storage device that employs such a spin-valve element is provided.