Perpendicular magnetic recording medium and process for manufacture thereof

A perpendicular magnetic recording medium comprising:

• a base,
• at least a ground layer,
• a first magnetic recording layer,
• a second magnetic recording layer, and
• at least a third magnetic recording layer, said layers being provided in this order on the base, wherein
• the first magnetic recording layer, the second magnetic recording layer and the at least a third magnetic recording layer are ferromagnetic layers of a granular structure in which grain boundary parts made of a non-magnetic substance are each formed between crystal grains each grown in a columnar shape,
• A<B when an average particle diameter of the crystal grains in the first magnetic recording layer is taken as A nm and an average particle diameter of the crystal grains in the second magnetic recording layer is taken as B nm, and
• the average particle diameter of the magnetic particles of an upper magnetic recording layer selected from the second and third magnetic layers, relative to the base side is larger than the average particle diameter of the magnetic particles of a lower magnetic recording layer selected from the first and second magnetic layers, relative to the upper magnetic recording layer, and
• further comprising a non-magnetic granular layer between the ground layer and the first magnetic recording layer, the non-magnetic granular layer having an average particle diameter smaller than the average particle diameter of the first magnetic recording layer.