Uni Hamburg Fachbereich Physik
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Implementation of temperature in micromagnetic simulations

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Micromagnetic simulations

Using the principles and results stated in 'theory' we started programming an evolver class for OOMMF. This class is called thetaevolve and is based on the eulerevolve class which comes with the OOMMF standard distribution. The main changes made were
1) an altered calculation of dM/dt, which takes into account temperature and
2) the implementation of a routine to produce (pseudo)random gaussian numbers.
This routine is platform independent what should result in identical results for identical problems no matter on which system the program is run.

With thetaevolve added to the original distribution we are able to investigate the influence of temperature. Preliminary results are consistent with theory, but we have done only basic validation work yet. Below is an example to illustrate how temperature affects spin dynamics.

Here the components Mx and My of a single spin's magnetization with anisotropy along the z-axis are plotted. The blue line is the precession at temperature 0K, the red one is the precession of the same spin, but at 50K.
One can clearly see, that at 50K the spin still spirals towards the energetic minimum, but the curve is irregular now.

more results coming soon...