Spin Accumulation Magnetic Head with Anti-Parallel Injection
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Solution Overview
Problem
Current magnetic recording/reproducing heads face challenges in achieving high resolving power and output due to limitations in gap length and magnetic substance interval, which affects their ability to handle high recording densities like 1 Tbit/in^2, and conventional spin accumulation elements have insufficient output and are difficult to miniaturize further without degrading magnetic characteristics.
Innovation Solution
The implementation of a spin accumulation element with multiple spin injection parts, where the first and second magnetic conductors have anti-parallel magnetization directions, and a third magnetic conductor for voltage detection, increases the accumulation of spin electrons and output voltage by utilizing tunneling junctions and antiferromagnetic conductors to enhance the spin diffusion length and output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the magnetic substance interval is narrowed to increase output voltage, then the output voltage increases, but the magnetic characteristics are degraded due to magnetic interaction between two magnetic substances
Solution Approach 1:
A non-magnetic substance layer is introduced between the first magnetic substance and the second magnetic substance. This intermediary non-magnetic layer prevents direct magnetic interaction between the two magnetic substances while allowing the spin accumulation effect to occur, thereby maintaining magnetic characteristics while enabling increased output voltage through optimized electrode configuration.
Solution Approach 2:
The invention changes the physical and chemical parameters of the non-magnetic substance layer, including its thickness, material composition, and electrical conductivity. By optimizing these parameters, the spin diffusion length is extended and the spin accumulation effect is enhanced, allowing increased output voltage without requiring the magnetic substances to be in direct contact.
2Measurement precision
If the gap length between shields is reduced to increase resolving power, then the resolving power increases, but it becomes difficult to manufacture with conventional techniques
Solution Approach 1:
The reproducing head is segmented into multiple functional layers including first shield, first magnetic substance, non-magnetic substance layer, second magnetic substance, and second shield. This segmentation allows the gap between shields to be distributed and controlled through multiple thin layers, making it feasible to achieve small effective gap lengths using conventional thin-film deposition techniques.
Solution Approach 2:
The invention transitions from a planar gap structure to a multi-layered vertical structure. By stacking magnetic and non-magnetic layers in the vertical dimension, the effective gap length is reduced while maintaining manufacturability through standard thin-film fabrication processes, thereby achieving high resolving power without excessive manufacturing difficulty.
3Power
If the spin diffusion length is increased to improve output, then the output voltage increases, but the device structure becomes more complex
Solution Approach 1:
The spin diffusion length is increased by changing the material parameters of the non-magnetic substance layer, such as selecting materials with high electrical conductivity and appropriate spin scattering properties. By optimizing the thickness and composition of this layer, the spin diffusion length is extended, allowing spin polarized electrons to travel farther and accumulate more effectively, thereby increasing output voltage without adding structural 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 configuration results in a magnetic reproducing head with significantly increased output voltage, up to 100% or more, and higher resolving power, enabling effective operation at high recording densities without the need for further miniaturization of magnetic substance intervals, thus overcoming the limitations of conventional designs.
Implementation Method 1
The spin accumulation effect is a phenomenon in which when a current is passed from a ferromagnetic substance to a non-magnetic metal, spin polarized electrons are accumulated in the non-magnetic metal in the range of spin diffusion length λ
Implementation Method 2
a first tunneling junction 2 formed on the non-magnetic conductor 1... in contact with the non-magnetic conductor through the tunneling junction
Implementation Method 3
the magnetization directions of the first magnetic conductor 3 and the second magnetic conductor 8 are anti-parallel to each other... increase the accumulation of spin electrons
Implementation Method 4
a third magnetic conductor 6... for voltage detection... An output voltage due to the spin accumulation effect is detected as a potential difference between the non-magnetic conductor 1 and the third magnetic conductor 6
Implementation Method 5
the first magnetic conductor 3 of the first spin injection part 10 is fixed by a first antiferromagnetic conductor 4 and the second magnetic conductor 8 of the second spin injection part 11 is fixed by a second antiferromagnetic conductor 4
Data Source
AI summary
Embodiments of the present invention provide an accumulation element with high resolving power and high output suitable for magnetic recording and reproducing at high recording density. According to one embodiment, a plurality of spin injection parts and are provided to increase the total amount of spin electrons. The spin accumulation element is composed of a non-magnetic conductor, a first magnetic conductor, a second magnetic conductor, and a third magnetic conductor, each of which are in contact with the non-magnetic conductor through the tunneling junction. An output voltage due to the spin accumulation effect is detected as a potential difference between the non-magnetic conductor and the third magnetic conductor. The first magnetic conductor of the first spin injection part is fixed by a first antiferromagnetic conductor and the second magnetic conductor of the second spin injection part is fixed by a second antiferromagnetic conductor so that their directions of magnetization are anti-parallel to each other.