Patent ID: 9012046
Filing Date: 2015-04-21
Classification: G11B

Abstract:
1. A perpendicular magnetic recording medium comprising: a nonmagnetic substrate; a nonmagnetic underlayer consisting of ruthenium and 10 to 50 at % of at least one element of titanium and silicon; a perpendicular magnetic recording layer formed in contact with the nonmagnetic underlayer and containing platinum and at least one of iron and cobalt; a mixed region of the nonmagnetic underlayer, in which at least some components of the perpendicular magnetic recording layer are mixed, containing ruthenium, nitrogen, and platinum, at least one of iron and cobalt, and at least one element selected from the group consisting of titanium and silicon; and a non-recording portion containing nitrogen and platinum, at least one of iron and cobalt, and at least one element selected from the group consisting of titanium and silicon, wherein a content of at least one element selected from the group consisting of titanium and silicon in the mixed region of the nonmagnetic underlayer is smaller by not less than 5 at % than a content of the element in the nonmagnetic underlayer, and wherein the mixed region of the nonmagnetic underlayer and the non-recording portion are demagnetized by forming a mask layer having patterns regularly arranged in a longitudinal direction on the perpendicular magnetic recording layer, and irradiating gas ion to the perpendicular magnetic recording layer and the nonmagnetic underlayer which are not covered with the mask layer using nitrogen gas or a mixture of nitrogen gas and at least one gas selected from the group consisting of helium, hydrogen, and B