Topological excitations in statistical field theory at the upper critical dimension

We present a high-precision Monte Carlo study of the classical Heisenberg model in four dimensions. We investigate the properties of monopole-like topological excitations that are enforced in the broken-symmetry phase by imposing suitable boundary conditions. We show that the corresponding magnetization and energy-density profiles are accurately predicted by previous analytical calculations derived in quantum field theory, while the scaling of the low-energy parameters of this description questions an interpretation in terms of particle excitations. We discuss the relevance of these findings and their possible experimental applications in condensed-matter physics.

Finite-size scaling in ferromagnetic spin systems on the pyrochlore lattice

In this paper we present the results of the high-performance computations for the Ising model, the XY-model and the classical Heisenberg model for the pyrochlore lattice. We used Wolff and Swendsen-Wang cluster algorithms with GPU parallelization for the calculations. We obtained critical exponents and critical temperatures using finite-size scaling approach.

Some Factors Affecting on Magnetic Characteristic Quantities and Tc Curie Phase Transition Temperature of the Ni Nanoparticles by the Classical Heisenberg Model

This paper investigates the effect of particle size D = 4.51nm, 5.03nm, 5.42nm, 5.91nm, rate of heat 4.1012K/s, 4.1013K/s, 4.1014K/s on magnetic characteristic quantities: Magnetization M, specific heat Cv, energy E, magnetic susceptibility c and Tc Curie phase transition temperature by classical Heisenberg model. The results show when increasing D particle size then Tc Curie transition temperature increases and when increasing rate of heat then Tc decreasing. In addition, there is the influence of D size and heating rate on magnetic characteristic quantities.

Vegas: Software package for the atomistic simulation of magnetic materials

We present an open-source software package, Vegas, for the atomistic simulation of magnetic materials. Using the classical Heisenberg model and the Monte Carlo Metropolis algorithm, Vegas provides the required tools to simulate and analyze magnetic phenomena of a great variety of systems. Vegas stores the history of the simulation, i.e. the magnetization and energy of the system at every time step, allowing to analyze static and dynamic magnetic phenomena from results obtained in a single simulation. Also, standardized input and output file formats are employed to facilitate the simulation process and the exchange and archiving of data. We include results from simulations performed using Vegas, showing its applicability to study different magnetic phenomena.