Perpendicular magnetic recording medium and method for making
US5525398A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 20, 1992 |
| Grant date | Jun 11, 1996 |
| Priority date | — |
| Expiry date | Mar 20, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/265
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A perpendicular magnetic recording medium has a magnetic layer comprised of two stacked sublayers each in the form of ferromagnetic metal thin film consisting of columnar crystal grains wherein the angle .theta. between the average growth direction of the columnar crystal grains and a normal to the substrate is .theta..gtoreq.45.degree. for the lower sublayer and .theta..ltoreq.30.degree. for the upper sublayer, and the mean maximum diameter of columnar crystal grains of the lower sublayer is not smaller than the mean maximum diameter of columnar crystal grains of the upper sublayer. An apparatus suitable for the evaporation of the magnetic layer is arranged as shown in the Figure. Magnetic flux associated with the upper sublayer finds an escape to the lower sublayer, preventing formation of a closed loop of magnetic flux within the columnar crystal grains of the upper sublayer. The lower sublayer is magnetized, thus contributing to an improvement in reproduction output.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.