Non-Equilibrium Magnetic Relaxation in High Coercivity Nanostructures

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A world-wide effort is in progress to understand the high speed switching process in high coercivity magnetic media in order to optimize materials capable of supporting recording data rates projected to approach 1GHz. Here it is proposed to attack the problem in collaboration with Seagate, a media manufacturer, experimentally and theoretically with four specific objectives: a) An integrated microsensor will be fabricated photolithographically to detect M(t). A unique fast switch using two pressurized spark gaps in series will be built which should provide field pulses of 4000 Oe with rise times ~0.1 ns. b) Thin films with coercivities of 2000-4000 Oe will be sputtered both at Alabama and at Seagate, and thoroughly characterized magnetically and structurally. Material development will be guided by the experimental switching data, compared to the predictions of the model. c) A micromagnetic model will be developed in which the damping constant depends on the fineness of the discretization. A fast multipole method will be used to allow the efficient compilation of magnetostatic field. d): New prototype media based on the predictions of this study will be prepared at Seagate and recording performance analyzed to define an optimized high frequency media product. Finally, a program integrating research in education will be carried out at the graduate, undergraduate and middle-school levels.