Magnetic recording medium, production process thereof, and magnetic recording and reproducing apparatus

Abstract

A magnetic recording medium having a non-magnetic substrate; an orientation-regulating layer for regulating layer for regulating the crystal orientation of a layer provided directly thereon; a perpendicular magnetic layer in which easy-magnetization axes are oriented generally perpendicular to the substrate; and a protective layer is disclosed. The perpendicular magnetic layer is formed from a material containing Co as a primary component and at least Cr, Pt, and Nd. A process to produce the magnetic recording medium and a magnetic recording and reproducing apparatus are also disclosed.

1 . A process for producing a magnetic recording medium, which comprises successively forming on a non-magnetic substrate, an orientation regulating layer for regulating the crystal orientation of a layer provided directly thereon, a perpendicular magnetic layer in which easy-magnetization axes are oriented generally perpendicular to the substrate, and a protective layer, wherein 
 the perpendicular magnetic layer is formed through sputtering by use of a sputtering target comprising a material containing Co as a primary component and at least Cr, Pt, and Nd, in which the Cr content is 18 to 28 at%, the Pt content is 10 to 20 at%, and the Nd content is 0.5 to 8 at%.    
     
     
         2 . A process for producing a magnetic recording medium according to  claim 1 , which further comprises forming a soft magnetic layer before formation of the orientation-regulating layer, and exposing the surface of the soft magnetic layer to a gas selected from among oxygen gas, nitrogen gas, a mixture of oxygen gas and nitrogen gas, and a gas containing oxygen gas and nitrogen gas.  
     
     
         3 . A process for producing a magnetic recording medium according to  claim 1 , wherein, when the perpendicular magnetic layer is formed the pressure of a sputtering gas is, regulated to 3 to 20 Pa.  
     
     
         4 . A process for producing a magnetic recording medium according to  claim 3 , which further comprises forming a soft magnetic layer before formation of the orientation-regulating layer, and exposing the surface of the soft magnetic layer to a gas selected from among oxygen gas, nitrogen gas, a mixture of oxygen gas and nitrogen gas, and a gas containing oxygen gas and nitrogen gas.