Perpendicular Magnetic Recording Medium Ru Seed Layer
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Solution Overview
Problem
The challenge lies in forming a magnetic recording medium with an L10 ordered alloy having a (001) orientation suitable for perpendicular magnetic recording using a Ru seed layer with a (002)-oriented hcp structure, as the (001) face of the L10 ordered alloy does not epitaxially grow well on the six-fold symmetric (002) face of the hcp structure.
Innovation Solution
A magnetic recording medium is constructed with a substrate, a first Ru seed layer, a second ZnO seed layer, and a third MgO seed layer, optionally including an orientation controlling layer and a non-magnetic intermediate layer of Pt, to achieve the desired (001) orientation of the L10 ordered alloy in the magnetic recording layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Ru seed layer with (002)-oriented hcp structure is used, then the magnetic recording medium can be manufactured with simpler seed layer structure, but the L10 ordered alloy cannot achieve proper (001) orientation for perpendicular magnetic recording
Solution Approach 1:
An MgO intermediate layer is introduced between the Ru seed layer and the L10 ordered alloy magnetic recording layer. The MgO layer serves as a mediator that transforms the crystal orientation relationship: the Ru (002) face orientations the MgO (001) face, which in turn orients the L10 ordered alloy (001) face. This intermediary layer resolves the incompatibility between the hexagonal Ru structure and the cubic L10 ordered alloy structure, enabling proper perpendicular magnetic recording orientation.
Solution Approach 2:
The invention changes the crystallographic orientation parameters of the seed layer system. Instead of directly using Ru (002) to orient the L10 ordered alloy, the system transitions through MgO (001) orientation. This parameter change in the intermediate layer's crystal orientation enables the final magnetic recording layer to achieve the required (001) orientation for perpendicular recording, while still using the simpler Ru (002) seed layer structure.
2Quantity of substance
If the grain diameter of magnetic crystal grains is reduced to increase recording density, then the recording density increases, but the thermal stability of recorded magnetization decreases
Solution Approach 1:
The magnetic recording layer uses a composite granular structure consisting of L10 ordered alloy magnetic crystal grains embedded in a non-magnetic matrix. The L10 ordered alloy provides high magnetocrystalline anisotropy which compensates for the reduced thermal stability caused by smaller grain sizes. This composite structure enables both high recording density (through small grain diameter) and sufficient thermal stability (through high anisotropy of the ordered alloy material).
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 allows for the successful formation of a magnetic recording medium with an L10 ordered alloy having a (001) orientation, overcoming the difficulty of using a Ru seed layer with a (002)-oriented hcp structure, and enhancing the magnetic recording density and thermal stability.
Implementation Method 1
the (001) face of the L10 ordered alloy, which is a four-fold symmetric square, is not epitaxially grown on the six-fold symmetric (002) face of the hcp structure
Data Source
AI summary
The purpose of the present invention is to provide a perpendicular magnetic recording medium which uses an Ru seed layer having a (002)-oriented hcp structure, and has a magnetic recording layer including a (001)-oriented L10 ordered alloy suitable to perpendicular magnetic recording. The magnetic recording medium of the present invention includes a substrate, a first seed layer containing Ru, a second seed layer containing ZnO, a third seed layer containing MgO, and a magnetic recording layer containing an ordered alloy, in this order, the first seed layer having the (002)-oriented hexagonal closest packed structure.