2D-computation problems in magnetic recording and printing

The appearance of both new principles and new technologies in the field of magnetic recording and printing, (perpendicular recording, thin film heads and layers..) leads to more and more complex associated computing and design tools. From the magnetic point of view, anisotropic and/or hysteresis phenomena are crucial here. The numerical and physical formulation of such problems is not easy and has not been totally explored up to now. Many other numerical problems can become very critical in the complete simulation of a whole recording structure, such as a head-disc couple : fluid mechanics problems (stabilisation of the flight of the head at 0.2 μm over the disc), signal theory (peakshift, diaphony ...) etc. We will here limit ourselves to the magnetic aspects : as regards computation, the finite element methods coupled with the minimum energy principle are systematically used. Tools and results in computing and designing magnetic structures are presented at the end of this paper.