Stripe-vortex transitions in ultrathin magnetic nanostructures.

In this work, the magnetic states in ultrathin nanostructures are investigated using Monte Carlo simulation, based on a Heisenberg model involving the short-range exchange coupling, long-range dipole-dipole interaction, and perpendicular anisotropy. An intriguing thermally driven magnetic structural transition from perpendicular stripe domain to flux closure (planar vortex) state, accompanied by an apparent thermal hysteresis effect and typical characteristics of the first-order phase transition, is revealed. Furthermore, it is found that the transition can be remarkably modulated by perpendicular anisotropy. The present work suggests a promising approach to manipulate the spin configurations in nanomagnets by adjusting temperature and perpendicular anisotropy. [ABSTRACT FROM AUTHOR]