HAMR Exchange Coupling Control Layer for Thermal Stability
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Solution Overview
Problem
Heat-assisted magnetic recording (HAMR) media faces challenges with vertical exchange coupling between softer and harder magnetic layers, as existing exchange coupling control layers in perpendicular magnetic recording (PMR) media are detrimental to HAMR, leading to lower switching temperatures and reduced thermal stability.
Innovation Solution
Incorporating a higher saturation magnetization (Ms) and/or higher Curie temperature (Tc) exchange coupling control layer between the hard and soft magnetic layers to enhance vertical exchange coupling, increasing the exchange spring strength and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an exchange coupling control layer is used in perpendicular magnetic recording (PMR) media to reduce vertical exchange coupling, then thermal stability is improved, but switching temperature decreases and thermal stability is reduced in heat-assisted magnetic recording (HAMR)
Solution Approach 1:
The patent changes the magnetic parameters of the exchange coupling control layer by introducing a composition gradient, where the CoPt alloy ratio varies through the thickness of the layer. This gradient allows the layer to have different magnetic properties at different depths, enabling it to provide thermal stability while maintaining appropriate exchange coupling for HAMR switching.
Solution Approach 2:
The exchange coupling control layer is constructed as a composite material with a CoPt alloy gradient structure. This composite approach combines regions of different magnetic hardness and exchange coupling strength within a single layer, allowing simultaneous optimization of thermal stability and switching characteristics.
2Reliability
If vertical exchange coupling between soft and hard magnetic layers is reduced, then thermal stability is improved, but driving force for magnetization switching is reduced
Solution Approach 1:
The patent applies local quality by creating spatial variation in the magnetic properties of the exchange coupling control layer through the CoPt composition gradient. Different regions of the layer provide different levels of exchange coupling, with the gradient designed to provide strong coupling where needed for switching while maintaining overall thermal stability.
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 increases the driving force for magnetization switching of the hard magnetic layer, improves recording performance by extending the switching temperature window, and enhances thermal stability, ensuring reliable data retention.
Implementation Method 1
An exchange coupling control layer is between the first magnetic layer and the second magnetic layer. The exchange coupling control layer is magnetic and increases vertical exchange coupling between the first magnetic layer and the second magnetic layer.
Implementation Method 2
A write head operable to produce a magnetic field. The magnetic field is sufficient to change the magnetization of the second magnetic layer at a Tc (Curie temperature) of the exchange control layer.
Implementation Method 3
The magnetic field is sufficient to change the magnetization of the second magnetic layer at a Tc (Curie temperature) of the exchange control layer.
Implementation Method 4
Heat-assisted magnetic recording (HAMR) media faces challenges with vertical exchange coupling between softer and harder magnetic layers
Data Source
AI summary
An apparatus includes a first magnetic layer. A second magnetic layer overlies the first magnetic layer and is magnetically softer than the first magnetic layer. An exchange control layer is between the first magnetic layer and the second magnetic layer. The includes a higher Ms (saturation magnetization) than the first magnetic layer at room temperature.