Perpendicular Magnetic Recording Medium Underlayer Grain Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current perpendicular magnetic recording media face challenges in achieving high recording density while maintaining low noise and thermal decay resistance, as the downsizing of magnetic crystal grains leads to increased medium noise and reduced thermal stability, and existing techniques fail to achieve uniform grain distribution and alignment effectively.
Innovation Solution
A perpendicular magnetic recording medium is developed with a layered structure comprising a nonmagnetic substrate, underlayers with specific elements such as Ag, Ir, Ni, and Si, and a magnetic recording layer, which improves grain alignment and distribution, reducing transition noise and maintaining thermal stability through the use of underlayers with elements like Pt, Pd, and Ti.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If magnetic crystal grains are downsized to reduce bit boundary unevenness, then recording density and noise are improved, but thermal decay resistance decreases
Solution Approach 1:
The patent applies local quality by creating a grain boundary region with different composition (containing Si and/or Ge) surrounding each magnetic crystal grain. This grain boundary region has distinct properties from the interior of the grains, providing localized structural support that maintains grain size uniformity while preserving thermal stability through the specific composition and structure of the boundary regions.
Solution Approach 2:
The patent uses composite materials by combining magnetic crystal grains containing specific elements (Co, Pt, Pd, Rh, Ir) with grain boundary regions containing Si and/or Ge. This composite structure allows the magnetic grains to maintain small sizes for high density while the composite grain boundary regions provide structural integrity and thermal stability, resolving the contradiction between grain size reduction and thermal decay resistance.
2Manufacturing precision
If material forming grain boundary region is added to downsize magnetic crystal grains, then grain size is reduced, but alignment of magnetic crystal grains worsens due to material diffusion
Solution Approach 1:
The patent applies preliminary action by forming the underlayer with specific composition (containing Ag, Ir, Ni, Pd, Pt, Rh, Hf, Re, Ru, Ti, Ta, Zr, Mg, or Al) before forming the magnetic recording layer. This underlayer is prepared in advance to provide a controlled foundation that prevents subsequent diffusion of grain boundary materials, thereby maintaining grain alignment while enabling grain size reduction in the magnetic recording layer.
Solution Approach 2:
The underlayer acts as an intermediary between the substrate and the magnetic recording layer. It contains specific elements that serve as diffusion barriers, preventing the grain boundary region materials (Si and/or Ge) from diffusing into the magnetic crystal grains and disrupting their alignment. This intermediary layer enables grain size control without compromising grain orientation.
3Stability of the object's composition
If film thickness of underlayer or magnetic recording layer is increased to improve grain alignment, then alignment is improved, but distance between magnetic head and soft magnetic backing layer increases causing spacing loss
Solution Approach 1:
The patent applies parameter changes by optimizing the composition and thickness of the underlayer rather than increasing the overall film thickness. The underlayer contains specific elements (Ag, Ir, Ni, Pd, Pt, Rh, Hf, Re, Ru, Ti, Ta, Zr, Mg, or Al) at controlled concentrations that provide grain alignment through compositional control rather than thickness increase, thereby maintaining magnetic field strength while achieving proper grain orientation.
Data Source
AI summary
At least three underlayers, i.e., a first underlayer containing, as a main component, at least one element selected from Ag, Ir, Ni, Pd, Pt, Rh, Hf, Re, Ru, Ti, Ta, Zr, Mg, and Al, a second underlayer containing Mg or Al and Si, and a third underlayer containing, as a main component, at least one element selected from Pt, Pd, Ru, Rh, Co, and Ti, are formed between a substrate and magnetic recording layer.