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We simulate antiferromagnetic thin films. Dipole-dipole and antiferromagnetic exchange interactions as well as uniaxial and quadrupolar anisotropies are taken into account. Various phases unfold as the corresponding parameters, J, D and C,…

Statistical Mechanics · Physics 2009-11-11 J. J. Alonso , J. F. Fernandez

The metastable behavior of a kinetic Ising--like ferromagnetic model system in which a generic type of microscopic disorder induces nonequilibrium steady states is studied by computer simulation and a mean--field approach. We pay attention,…

Statistical Mechanics · Physics 2009-11-10 P. I. Hurtado , J. Marro , P. L. Garrido

Effects of disorder and external field on the competing spin-Peierls and antiferromagnetic states are studied theoretically in terms of the numerical transfer matrix method applied to a quasi one-dimensional spin 1/2 Heisenberg model…

Strongly Correlated Electrons · Physics 2007-05-23 Hitoshi Seo , Yukitoshi Motome , Naoto Nagaosa

Resistivity measurements are widely exploited to uncover electronic excitations and phase transitions in metallic solids. While single crystals are preferably studied to explore crystalline anisotropies, these usually cancel out in…

In real magnets the tendency towards ferromagnetism, promoted by exchange coupling, is usually frustrated by dipolar interaction. As a result, the uniformly ordered phase is replaced by modulated (multi-domain) phases, characterized by…

Statistical Mechanics · Physics 2018-12-26 Sergio A. Cannas , Alessandro Vindigni

The competition between shape and perpendicular magnetic anisotropies (PMA) in magnetic thin films gives rise to unusual magnetic behaviors. In ferromagnetic films with moderate PMA the magnetic domain configuration transitions from planar…

We study numerically the thermodynamic properties of the spin nematic phases in a magnetic field in the spin-1 bilinear-biquadratic model. When the field is applied, the phase transition temperature once goes up and then decreases rapidly…

Strongly Correlated Electrons · Physics 2020-10-14 Katsuhiro Tanaka , Chisa Hotta

The effect of the anisotropy in the exchange interaction on the phase diagrams and magnetization behavior of the Heisenberg thin film has been investigated with effective field formulation in a two spin cluster using the decoupling…

Statistical Mechanics · Physics 2015-06-17 Ümit Akıncı

Confinement effects on the phase transitions in antiferromagnets are studied as a function of the surface coupling v and the surface field h for bcc(110) films. Unusual topologies for the phase diagram are attained for particular…

Materials Science · Physics 2015-06-24 A. Diaz-Ortiz , J. M. Sanchez , J. L. Moran-Lopez

We investigate the Hubbard model on the anisotropic triangular lattice by means of the cellular dynamical mean field theory. The phase diagram determined in the Hubbard interaction versus temperature plane shows novel reentrant behavior in…

Strongly Correlated Electrons · Physics 2009-11-13 Takuma Ohashi , Tsutomu Momoi , Hirokazu Tsunetsugu , Norio Kawakami

The phase coexistence present through a first-order phase transition means there will be finite regions between the two phases where the structure of the system will vary from one phase to the other, known as a phase boundary wall. This…

The far-from-equilibrium low-temperature dynamics of ultra-thin magnetic films is analyzed by using Monte Carlo numerical simulations on a two dimensional Ising model with competing exchange ($J_0$) and dipolar ($J_d$) interactions. In…

Disordered Systems and Neural Networks · Physics 2009-11-07 P. M. Gleiser , F. A. Tamarit , S. A. Cannas , M. A. Montemurro

The two-dimensional Ising model with competing short range ferromagnetic interactions and long range antiferromagnetic interactions is perhaps the most simple one containing the minimal microscopic ingredients necessary for an appropriate…

Statistical Mechanics · Physics 2009-07-09 Sergio A. Cannas , Pablo M. Gleiser , Francisco A. Tamarit

Recently, it has been shown that two dimensional frustrated mixed-spin systems with anisotropic exchange interactions display supersolid phases in their ground state phase diagrams even in the absence of long-range interactions. In this…

Applied Physics · Physics 2020-02-19 F. Heydarinasab , J. Abouie

The disordered random-anisotropy magnetic nanoparticle systems with competing dipolar interactions and ferromagnetic exchange couplings are investigated by Monte Carlo simulations. Superspin glass (SSG) and superferromagnetic (SFM)…

Disordered Systems and Neural Networks · Physics 2015-05-27 Zhongquan Mao , Xi Chen

We investigate the details of pattern formation and transitions between different modulated phases in ultra-thin Fe films on Cu(001). At high temperature, the transitions between the uniform saturated state, the bubble state and the striped…

Mesoscale and Nanoscale Physics · Physics 2011-01-17 N. Saratz , U. Ramsperger , A. Vindigni , D. Pescia

Topological phase space disconnection has been recently found to be a general phenomenon in isolated anisotropic spin systems. It sets a general framework to understand the emergence of ferromagnetism in finite magnetic systems starting…

Statistical Mechanics · Physics 2014-07-29 F. Borgonovi , G. L. Celardo , B. Goncalves , L. Spadafora

Ultrathin magnetic films can be modeled as an anisotropic Heisenberg model with long range dipolar interactions. It is believed that the phase diagram presents three phases: A ordered ferromagnetic phase (I), a phase characterized by a…

Computational Physics · Physics 2007-05-23 M. Rapini , R. A. Dias , B. V. Costa

We show results from Monte Carlo simulations of a two dimensional Heisenberg model for ultrathin films with perpendicular anisotropy. A complete phase diagram is obtained as a function of anisotropy and temperature, spanning a wide range of…

Disordered Systems and Neural Networks · Physics 2009-11-13 Marianela Carubelli , Orlando V. Billoni , Santiago Pighin , Sergio A. Cannas , Daniel A. Stariolo , Francisco A. Tamarit

A model is studied for the theoretical description of nanoscale magnetic films with high perpendicular anisotropy. In the model the magnetic film is described in terms of single domain magnetic grains with Ising-like behavior, interacting…

Statistical Mechanics · Physics 2016-08-31 U. Nowak