Monte Carlo simulations of ultrathin magnetic dots

Abstract

In this work we study the thermodynamic properties of ultrathin ferromagnetic dots using Monte Carlo simulations. We investigate the vortex density as a function of the temperature and the vortex structure in monolayer dots with perpendicular anisotropy and long-range dipole interaction. The interplay between these two terms in the hamiltonian leads to an interesting behavior of the thermodynamic quantities as well as the vortex density.

Phase transition in ultrathin magnetic films with long-range interactions: Monte Carlo simulation of the anisotropic Heisenberg model

“…In a very preliminary calculation, Rapini et al 18 studied the model with true dipolar long-range interactions by using open boundary conditions and perfoming the sum without a cutoff. Their results led them to suspect a phase transition of the BKT type involving the unbinding of vorticesantivortices pairs in the model.…”

“…A lot of theoretical work has been done on the morphology and stability of these magnetic structures. [12][13][14] Beside that, it has been observed the existence of a switching transition from perpendicular to in-plane ordering at low but finite temperature: [15][16][17][18] at low temperature the film magnetization is perpendicular to the film surface; as temperature rises the magnetization flips to an in-plane configuration. Eventually the out-of-plane and the in-plane magnetization become zero.…”

Velocity, temperature, and normal force dependence on friction: An analytical and molecular dynamics study

“…During the sliding the kinetic energy can be dissipated by a phononic, electronic, or a magnetic mechanism. The first mechanism is related to the excitation of phonons 4, the second one with the excitation of electron–hole pairs 1, and the third mechanism with the excitation of spin waves and/or vortex–anti‐vortex pairs 5, 6. In this work we want to fix our attention on the dissipation associated with the phononic channel.…”