Magnetic recording medium for high density recording and magnetic storage device using same

A magnetic recording medium comprising at least a first magnetic layer, a second magnetic layer and a third magnetic layer, which are formed in order on a substrate through an underlying film;

• wherein:
• said first magnetic layer is a cobalt-chromium alloy layer or a cobalt-chromium-platinum alloy layer;
• said second and third magnetic layers are each a cobalt-base alloy layer containing chromium, platinum and boron;
• said first magnetic layer has a thickness smaller than a thickness of said second magnetic layer;
• the concentration of chromium contained in said first magnetic layer is lower than the concentration of chromium contained in said second magnetic layer;
• and
• the concentration of chromium contained in said third magnetic layer is lower than the concentration of chromium contained in said second magnetic layer.

A magnetic recording medium comprising, on a substrate, an underlying film, a magnetic film and a protective film;

• wherein:
• said magnetic film has a plurality of magnetic layers stacked without interposition of any non-magnetic layer;
• said plurality of magnetic layers comprises first, second, third and fourth magnetic layers;
• said first magnetic layer is disposed between said underlying film and said second magnetic layer;
• said second magnetic layer is disposed between said first magnetic layer and said third magnetic layer;
• said third magnetic layer is disposed between said second magnetic layer and said fourth magnetic layer;
• said fourth magnetic layer is disposed between said third magnetic layer and said protective film;
• said first magnetic layer is a cobalt-base alloy layer containing chromium;
• said second, third and fourth magnetic layers are each a cobalt-base alloy layer containing chromium, platinum and boron;
• the thickness of said first magnetic layer is smaller than the thickness of said second magnetic layer;
• the concentration of chromium contained in said first magnetic layer is lower than the concentration of chromium contained in said second magnetic layer;
• the concentration of chromium contained in said third magnetic layer is lower than the concentration of chromium contained in said second magnetic layer;
• and
• the sum of the concentration of cobalt and the concentration of platinum contained in said fourth magnetic layer is higher than the sum of the concentration of cobalt and the concentration of platinum contained in said third magnetic layer.