An atomistic parallel Monte Carlo algorithm has been implemented on the GPU. This is very useful for computing micromagnetic parameters temperature dependences in multiscale models. The dipole-dipole interaction has also been included, which allows shape anisotropy effects to be considered – for example hysteresis loops may be computed very efficiently at any temperature.

The example below shows an 80 nm x 80 nm x 1 nm triangle without any magneto-crystalline anisotropy. The dipole-dipole interaction results in a shape anisotropy however. The spins are set initially along the plane perpendicular direction, so a hard axis. As the system is thermalized (entropy increases) with the Monte Carlo algorithm the free energy tends to a lower energy state, thus the spins align mostly in the plane.