A Split-Pole-Gapped NFT Write Head Design for Transition Curvature Reduction in Heat-Assisted Magnetic Recording

A write head design consisting of a split pole and a gapped near-field transducer is presented. Through simulation, we found our design can produce a maximum effective cross-track recording field gradient of 300 Oe/nm, and a maximum difference of 3.6 kOe between the center and +/- 20 nm away in the cross-track direction in the recording media near the magnetic gap (MG). The tradeoff between improved cross-track magnetic gradient and loss of optical efficiency due to parasitic absorption by the pole is studied as a function of the thickness of a low optical-index separator between the MG and the optical gap (OG). The separator is tapered to bring the cross-track field gradient close to the OG near the air bearing surface, while limiting the total amount of interaction of the evanescent optical field with the pole. With this tapered low-index separator, we are able to preserve the recording field cross-track gradient and amplitude, while reducing the parasitic optical absorption in the recording head due to pole proximity.