CPP Magneto-Resistive Device Shield Layer Coupling
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Solution Overview
Problem
Current magneto-resistive effect devices face challenges in achieving ultra-high recording densities due to difficulties in creating an antiparallel magnetization state between ferromagnetic layers without relying on specific intermediate films, which limits the reduction of the read gap length and results in instability and low reliability.
Innovation Solution
A CPP structure with a magneto-resistive effect unit sandwiched between shield layers, where the ferromagnetic layers are indirectly magnetically coupled through exchange coupling function gap layers, allowing for antiparallel magnetization without the need for intermediate films, and utilizing magnetization direction control means to stabilize the magnetization directions of the shield layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating layers are used between shield layers in CIP structure, then device reliability is improved, but device area increases and heat dissipation efficiency decreases
Solution Approach 1:
The patent removes the insulating gap layers between the shield layers, extracting the harmful element that was causing increased device area and poor heat dissipation. By directly contacting the shield layers with the magneto-resistive effect unit, the device area is reduced while maintaining reliability through the CPP structure design.
Solution Approach 2:
The patent introduces a nonmagnetic intermediate layer as a mediator between the ferromagnetic layers, enabling the CPP structure to function without insulating layers. This intermediate layer facilitates direct electrical contact between shield layers while maintaining the necessary magnetic properties for the magneto-resistive effect.
2Manufacturing precision
If read gap length is reduced to increase recording density, then linear recording density is improved, but device area decreases and heat dissipation efficiency worsens
Solution Approach 1:
The patent transitions from the CIP (current in-plane) structure to the CPP (current perpendicular-to-plane) structure, changing the dimension in which current flows. This dimensional change allows the read gap to be reduced in the vertical direction while maintaining adequate heat dissipation pathways through the layered structure, thus improving linear recording density without severely compromising heat dissipation.
3Stability of the object's composition
If intermediate films are used to create antiparallel magnetization state, then magnetization stability is improved, but device complexity increases and read gap length cannot be reduced further
Solution Approach 1:
The patent removes the need for specific intermediate films (such as antiferromagnetic layers) that were traditionally used to create and maintain antiparallel magnetization states. By using the CPP structure with direct shield layer contact, the magneto-resistive effect unit can achieve the desired magnetization state without these additional complex intermediate layers, thereby reducing device complexity while maintaining magnetization stability.
4Manufacturing precision
If shield gap is narrowed to increase recording density, then linear recording density is improved, but device area decreases
Solution Approach 1:
The patent adopts the CPP structure where current flows perpendicular to the plane of the layers, allowing the shield gap to be narrowed in the vertical direction to increase linear recording density. This dimensional change in current flow direction enables reduced device area without the same constraints that limited the CIP structure, as the magneto-resistive effect is measured across the narrowed gap rather than along the in-plane current path.
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 enables a shorter read gap length, improving linear recording densities and achieving stable magneto-resistive effects for higher reliability in ultra-high recording densities.
Implementation Method 1
a magneto-resistive effect unit (8), wherein the first ferromagnetic layer (130) and the second ferromagnetic layer (150) have a parallel magnetization state or an antiparallel magnetization state according to a magnetic field from a recording medium
Implementation Method 2
the first ferromagnetic layer (130) is indirectly magnetically coupled to the first shield layer (3) having a controlled magnetization direction via a first exchange coupling function gap layer (300), and the second ferromagnetic layer (150) is indirectly magnetically coupled to the second shield layer (5) having a controlled magnetization direction via a second exchange coupling function gap layer (500)
Data Source
AI summary
The invention provides a magneto-resistive effect device of the CPP (current perpendicular to plane) structure, having a magneto-resistive effect unit, and a first shield layer and a second shield layer located and formed such that the magneto-resistive effect unit is sandwiched between them, with a sense current applied in a stacking direction.