Calculations of magnetization configurations of SPT head using micromagnetic model

The whole magnetization configurations of single-pole-type (SPT) head and double-layered medium are calculated using a micromagnetic model, taking into account the magnetostatic interactions between an SPT head and a medium. This method enable us to obtain nano-scale magnetic structures formed in an SPT head which could not be obtained with a conventional method using a macromodel such as B-H curves. The head-field strength at a spacing of 7.5 nm beneath the main pole, with Ms=2.0 Wb/m2, reaches 950 kA/m including the image field of soft under-layer. Very complicated vortex-like magnetic domains and walls appear in the main pole and the return pole. Especially, at the edges of the return pole, the magnetizations have a large component normal to the air-bearing surface and this results in localized strong stray fields from the wings of return pole. The stray fields might erase the recorded bits on the neighboring tracks. Also, it is estimated that the delay time of a head field to the excitation field is 0.4 ns under the calculation conditions examined.