Perpendicular magnetic recording media with thin soft magnetic underlayers and recording systems comprising same

A perpendicular magnetic recording medium, comprising:

• (a) a non-magnetic substrate having a surface;
• and
• (b) a plurality of overlying thin film layers forming a layer stack on said substrate surface, said layer stack including a magnetically hard perpendicular magnetic recording layer structure and an underlying soft magnetic underlayer (SUL),
• wherein said perpendicular magnetic recording medium has only one SUL, and
• said SUL has a thickness of about 40 Å to about 100 Å,
• wherein the magnetically hard perpendicular magnetic recording layer structure comprises a granular perpendicular magnetic recording layer wherein the magnetic grains are exchange coupled together, and an overlying continuous perpendicular magnetic recording layer wherein the magnetic grains are exchange coupled laterally together, and the magnetic grains in the continuous perpendicular layer are more strongly exchange coupled than the magnetic grains in the granular perpendicular magnetic recording layer.

A perpendicular magnetic recording medium, comprising:

• (a) a non-magnetic substrate having a surface;
• and
• (b) a plurality of overlying thin film layers forming a layer stack on said substrate surface, said layer stack including a magnetically hard perpendicular magnetic recording layer structure and an underlying soft magnetic underlayer (SUL),
• wherein said perpendicular magnetic recording medium has only one SUL, and
• said SUL has a thickness of about 40 Å to about 100 Å,
• wherein said layer stack further comprises at least one Ru-containing material interlayer between said perpendicular magnetic recording layer and said SUL.