Energy barrier distributions for magnetic nanoparticles with competing cubic and uniaxial anisotropies

• Blocking temperature increases with relative cubic and uniaxial anisotropies.
• Energy barrier distribution is two-peaked for random orientation of axes.
• Aligned uniaxial axes give only single peaks for the energy barrier distribution.
• The two peak structure disappears above a critical anisotropy ratio.
• Coercive field for aligned is larger than for non-aligned axes.

We report in this study the effect of the competition between cubic and uniaxial anisotropies on the magnetic properties of magnetic nanoparticles. We have employed Monte Carlo simulations in our calculations and we have seen that the observed behavior is very different for the cases where easy uniaxial axes are completely random oriented or parallel to an external magnetic field. We have also calculated the effective energy barrier distribution probed during the isothermal magnetic relaxation and a two peak structure is observed only for a random orientation of uniaxial axes.