Simulation

There are two software packages underpinning the simulations performed
for this work. The first is the *Object Oriented MicroMagnetic
Framework*, or OOMMF (*Donahue and Porter*, 1999) provided by the National Institute
of Standards and Technology. OOMMF employs the finite difference (FD)
method which requires the *discretisation* (or segmentation, see
section 2.7.1) of a chosen geometry over a grid of
cells each of identical volume and cuboidal shape.

The second is *magpar* (*Scholz*, 2003, *Scholz* *et al.*, 2003a),
developed by Werner Scholz and the group of Prof. Fidler and Prof.
Schrefl of the Technische Universität Wien. This software uses the
hybrid finite element/boundary element method (FE/BE) and as such
requires that the chosen geometry be discretised with tetrahedral
volume elements which can be of variable volume and shape.

The aspect of these software packages which shifts the configuration of
the magnetisation on a step-wise basis is an *evolver*, based on
the Landau-Lifshitz-Gilbert (LLG) differential equation
(2.37).

Richard Boardman 2006-11-28