Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 28: Spindynamik / Ummagnetisierungsvorg
änge

MA 28.1: Talk

Thursday, March 11, 2004, 15:15–15:30, H23

A new method for atomistic spin-dynamics simulations with ab-intio accuracy — •Reinhard Singer, Ralf Drautz, and Manfred Fähnle — MPI für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany

We propose a new method to simulate the adiabatic spin dynamics in systems with magnetization singularities (vortex structures, Bloch points, extremely narrow domain walls in nanostripes etc.) with ab-initio accuracy but orders of magnitude faster than the conventional ab-initio spin dynamics simulation. It is based on the same equation of motion as the conventional simulation, i. e., a Gilbert like equation with a precission term and a damping term. In the conventional simulation the effective fields entering the precission term have to be calculated by the full ab-initio electon theory which renders the method very costly. In contrast, we determine the effective fields by our recently proposed spin-cluster-expansion technique which represents an analytical expression for the magnetic energy of a spin system with arbitrary multi-spin interactions. The expansion coefficients thereby are determined by the ab-initio density functional electron theory. Therefore the construction of the expansion is costly, but once a converged spin-cluster expansion is generated it can be used to calculate the energy of any spin configuration very effectively and probably with ab-initio accuracy.