Perpendicular Magnetic Recording Medium Seed Layer Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing perpendicular magnetic recording media face challenges in optimizing recording density and signal-to-noise ratio due to limitations in reducing orientational dispersion and crystal grain size while maintaining magnetic characteristics, as previous techniques either compromise on layer thickness or deteriorate magnetic separation.
Innovation Solution
A perpendicular magnetic recording medium is developed with a seed layer of NiFeCrMo and two non-magnetic intermediate layers, one made of CoCrMo and the other of Ru or RuW, to improve orientation and reduce thickness, achieving enhanced electromagnetic conversion and high recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the seed layer or intermediate layer is reduced to decrease crystal grain size, then the crystal orientation of the magnetic recording layer is deteriorated and magnetic separation is hindered
Solution Approach 1:
The patent divides the single intermediate layer into two distinct non-magnetic intermediate layers with different thicknesses and compositions. The first intermediate layer (closer to seed layer) has thickness of 1-3 nm and contains Ru, while the second intermediate layer has thickness of 3-6 nm and contains CoCrPt. This segmentation allows each layer to perform its specific function: the thinner first layer controls grain size without excessive thickness, while the thicker second layer maintains crystal orientation and magnetic separation, thus resolving the contradiction between reducing grain size and maintaining orientation.
2Loss of information
If the thickness of the seed layer or intermediate layer is reduced to improve S/N ratio, then the magnetic characteristics of the magnetic recording layer are deteriorated
Solution Approach 1:
The patent changes the parameters of the intermediate layer by dividing it into two layers with different thicknesses (1-3 nm for first layer, 3-6 nm for second layer) and different compositions (Ru-containing and CoCrPt-containing respectively). This parameter optimization reduces the total thickness compared to conventional single layers, thereby reducing noise and improving S/N ratio, while the specific composition and thickness distribution ensure that magnetic characteristics are maintained through proper crystal orientation control.
3Manufacturing precision
If conventional single intermediate layer structure is used, then the orientational dispersion and crystal grain size cannot be sufficiently reduced
Solution Approach 1:
The patent segments the intermediate layer into two functionally distinct layers with different thicknesses and compositions. The first non-magnetic intermediate layer (1-3 nm) primarily controls crystal grain nucleation and size, while the second non-magnetic intermediate layer (3-6 nm) primarily controls crystal orientation. This segmentation enables independent optimization of grain size and orientational dispersion, achieving superior magnetic recording characteristics despite the increased 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 effectively reduces orientational dispersion and crystal grain size, improving the signal-to-noise ratio and recording density, while maintaining the magnetic characteristics of the medium.
Implementation Method 1
The seed layer or the intermediate layer has a function of controlling, for example, the crystallinity, orientation, and crystal grain size of the magnetic recording layer formed thereon
Implementation Method 2
an underlayer that is made of a soft magnetic material and concentrates a magnetic flux generated by a magnetic head used to record information on the magnetic recording layer
Implementation Method 3
reduce the orientational dispersion Δθ50 of the c-axis which is the magnetization easy axis of the magnetic layer
Data Source
AI summary
A perpendicular magnetic recording medium is disclosed which is capable of reducing the orientational dispersion and crystal grain size of a magnetic recording layer, simultaneously reducing the thickness of a non-magnetic intermediate layer, hence, reducing noise, and improving S/N ratio and recording density characteristics. The medium includes a non-magnetic substrate, soft magnetic underlayer, seed layer, first non-magnetic intermediate layer, second non-magnetic intermediate layer, granular magnetic recording layer, exchange coupling force control layer, non-granular magnetic recording layer, protective layer, and lubricant layer sequentially formed on the non-magnetic substrate. The first and second non-magnetic intermediate layers are laminated to form a two-layer non-magnetic intermediate layer and the seed layer is made of a material having an fcc structure.