Magnetoresistance Element with Segmented Recording Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetoresistance effect elements used in magnetic random access memory (MRAM) face challenges in achieving high thermal stability for perpendicular magnetic recording, with existing structures failing to meet the required thermal stability index of 70, leading to increased switching currents and reduced data retention.
Innovation Solution
A magnetoresistance effect element with a three-layer structure comprising a second ferromagnetic layer, a non-magnetic coupling layer made of Ta, and a third ferromagnetic layer, where the second and third ferromagnetic layers are made of CoFeB alloy, and the non-magnetic coupling layer is sufficiently thin to maintain perpendicular magnetization and enhance thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional three-layer structure with thin ferromagnetic layers is used to achieve perpendicular magnetization, then perpendicular magnetic anisotropy is obtained, but the thermal stability index is insufficient (below 70)
Solution Approach 1:
The recording layer is divided into multiple ferromagnetic sub-layers (second ferromagnetic layer 109 and third ferromagnetic layer 204) separated by a non-magnetic coupling layer 203. This segmentation allows each sub-layer to contribute to perpendicular magnetic anisotropy while the cumulative thickness achieves the required thermal stability index of 70 or higher, resolving the contradiction between maintaining simple structure and achieving sufficient thermal stability.
2Stability of the object's composition
If the ferromagnetic layer thickness is increased to improve thermal stability, then thermal stability index improves, but the magnetoresistance change ratio decreases
Solution Approach 1:
By segmenting the recording layer into multiple thin ferromagnetic sub-layers (109 and 204) separated by a non-magnetic coupling layer (203), the total thickness can be increased to achieve thermal stability index of 70 or higher while each individual sub-layer remains thin enough to maintain high magnetoresistance change ratio. This resolves the contradiction between thermal stability and magnetoresistance performance.
Solution Approach 2:
The recording layer uses a composite structure combining multiple ferromagnetic materials (CoFeB alloy in layers 109 and 204) with a non-magnetic coupling material (Ta in layer 203). This composite structure enables the total thickness to be sufficient for thermal stability while maintaining the magnetic properties needed for high magnetoresistance change ratio through the interface effects between different materials.
3Use of energy by moving object
If perpendicular magnetization is implemented to reduce switching current, then switching current is reduced, but thermal stability is insufficient leading to increased bit error rate
Solution Approach 1:
The segmented recording layer structure with multiple ferromagnetic sub-layers (109 and 204) provides sufficient thermal stability index (70 or higher) through increased total thickness, preventing thermal fluctuations from causing spontaneous magnetization reversal. This ensures data retention reliability while maintaining the perpendicular magnetization configuration that enables low switching current operation.
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 achieves a thermal stability index of 80 or more, reducing switching currents and improving data retention while maintaining a high magnetoresistance change ratio, enabling efficient perpendicular magnetic recording.
Implementation Method 1
the demagnetizing field reduces the energy barrier caused during the magnetization reversal by the spin transfer torque
Implementation Method 2
The magnetization of the second ferromagnetic layer 109 is reversed by a spin transfer torque generated by a current supplied from the selection transistor
Implementation Method 3
The resistance value of the magnetoresistance effect element is reduced if the respective magnetizations of the first and second ferromagnetic layers 2106 and 2109 are parallel and is increased if these magnetizations are antiparallel
Data Source
AI summary
A magnetoresistance effect element including a recording layer of high thermal stability to perform perpendicular magnetic recording within a film surface, and a magnetic memory using the element. The element includes: a first ferromagnetic layer of an invariable magnetization direction; a second ferromagnetic layer of a variable magnetization direction; a first non-magnetic layer between the first and second ferromagnetic layers; current supply terminals connected to the first and second ferromagnetic layers; a non-magnetic coupling layer on a surface of the second ferromagnetic layer opposite the first non-magnetic layer; a third ferromagnetic layer of a variable magnetization direction on a surface of the non-magnetic coupling layer opposite the second ferromagnetic layer; and a second non-magnetic layer on a surface of the third ferromagnetic layer opposite the non-magnetic coupling layer. The second and third ferromagnetic layers have the same magnetization direction and are reversed in magnetization by spin injection with a current.