Including higher order anisotropy in modelling of hysteresis of NPs

Efficient hysteresis loop simulations of nanoparticle assemblies beyond the uniaxial anisotropy.
Alexandre Tamion, Edgar Bonet, Florent Tournus, Cécile Raufast, Arnaud Hillion, Oksana Gaier, and Véronique Dupuis
Phys. Rev. B 85, 134430 (2012)

Left: ZFC/FC magnetization curves and superparamagnetic m(H) at 300 K (in inset) of the Co :C. Right: Hysteresis loops at 2 K. The solids line correspond to the fits. The astroids associated with the biaxial fits are
shown in inset together with an enlargement of the merging region.