Unshielded perpendicular recording head for 1 Tb/in2

A full three-dimensional (3-D) self-consistent micromagnetic code has been employed to design an unshielded perpendicular writer for an areal density of 1 Tb/in(2). The head consists of a probe-type tip protruding from a collar. The tip has saturation magnetization (M-S) of 24 kG while the collar has lower M-S. The magnitude and orientation of anisotropy Held (H-k) in the tip is varied to obtain the best recording performance. The combination of high anisotropy write tip with low M. collar is shown to produce effective write fields in excess of 19 kOe and less than 20% track erasure for 10(7) passes. Introduction of in-plane anisotropy within the pole tip reduces head remanence sufficiently that on-track erasure exceeds a benchmark of 10(8) passes. The damping constant in Landau-Lifshitz-Gilbert equation has been varied to improve the frequency response. With damping constant equal to 1.0, simulations show that the head is capable of switching in approximately 0.15 ns.