The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 18, 1994
Filed:
Nov. 25, 1991
Hitachi, Ltd., Tokyo, JP;
Abstract
The magnetic recording medium includes a nonmagnetic substrate having different values of surface tension corresponding to surface free energy in a predetermined magnetic recording direction and in the direction substantially perpendicular thereto, a magnetic film epitaxially grown on the nonmagnetic substrate, and a protective film on the magnetic film. The surface of the nonmagnetic substrate is provided with irregular surfaces having gradients of 45 degrees .+-.10 degrees relative to the substrate surface. The magnetic film has a main component of an easy axis of magnetization in the magnetic recording direction. The hydrogen peroxide aqueous solution and nitric acid used for the surface treatment of the substrate affect differently the critical surface tension. The partial nonmetal layer can be partially worked to provide textures extending in the magnetic recording direction. The nonmagnetic substrate and the magnetic film are respectively made of substantially nickel-phosphorus and cobalt, and the partial nonmetal layer is made of carbon.