Patent ID: 7732069

Claim:
A system comprising: a write element for producing a write field, the write element having a write pole and a downstream write shield, the write pole having an area and a perimeter at an air bearing surface; and a magnetic medium facing the write element at the air bearing surface, the magnetic medium comprising: an upper layer having perpendicular anisotropy for recording data; and a lower layer for returning flux from the write pole to the downstream write shield; wherein a thickness of the lower layer is less than a ratio of the area of the write pole to the perimeter of the write pole times a ratio of a saturation magnetization of the write pole to a saturation magnetization of the lower layer, such that the lower layer is driven into saturation by the write field in a vicinity nearest the write pole; and wherein the write pole comprises a write pole tip facing the magnetic medium at the air bearing surface, and wherein a distance from the write pole to the lower layer is between half and twice a distance from the write pole tip to the downstream write shield.