Thermodynamic properties of antiferromagnetic ternary systems using a random-site Ising model

Pseudocritical behavior of ferromagnetic pure and random diluted nanoparticles with competing interactions: Variational and Monte Carlo approaches

“…The magnetic properties of bulk metallic systems having concurrently atomic disorder, dilution, competing interactions and characterized for exhibiting spin glass (SG) behavior have been widely studied from different points of view: experiment, theory and numerical simulation [1][2][3]. Among the systems with such characteristics, we can mention for instance CuMn [4], FeAu [5], FeAl [6][7][8][9], FeNiMn [10,11] and FeMnAl [11][12][13][14][15] alloys. These alloys are interesting due to the richness of magnetic phases that can be found such as ferromagnetic, antiferromagnetic, superparamagnetic, cluster glass, SG and RSG depending on stoichiometry, microstructure, degree of dilution, atomic disorder, magnetic field and temperature.…”

“…These alloys are interesting due to the richness of magnetic phases that can be found such as ferromagnetic, antiferromagnetic, superparamagnetic, cluster glass, SG and RSG depending on stoichiometry, microstructure, degree of dilution, atomic disorder, magnetic field and temperature. Typical Ising spin glass systems like those based on FeMnTiO 3 [16,17], Fe(Cu,Al)Dy [18], LiHoYF [19], FeAl [6,7,9,20] and FeMnAl [11,12,15] are good candidates to study SG and RSG related properties through Isingbased theoretical models where good agreement with experimental results has been achieved. In particular, pure SG and RSG behaviors, in ternary FeMnAl alloys, arise from several ingredients including random atomic distribution of the alloy constituent elements in the crystalline structure, dilution provided by Al atoms giving rise to bond randomness and, finally, competition among the different exchange integrals involved.…”

“…Both the free energy variational method based on the Bogoliubov inequality and a Metropolis Monte Carlo simulation in the framework of a nearest neighbor Ising model were considered. The former, as energy minimization tool, has been already successfully employed in describing the magnetic properties of this kind of systems where theoretical magnetic phase diagrams are in good agreement with the experimental ones [11,12,15]. The layout of the paper is as follows.…”

Cluster size effects in the magnetic properties of Fe$_p$-Al$_{q=1-p}$ alloys

“…Such cluster size properties have not been considered previously and better fits than those from Refs. [15][16][17][18][19][20][21][22][23][24][25][26][27] have been achieved. In addition, Monte Carlo simulations provide not only more precise values for the transition temperatures, but also can capture the real physics of the cluster size properties.…”

“…In order to try to explain this rather anomalous behavior of the phase diagram, several models (including classical and quantum) and theoretical procedures (including analytical approximations and computer simulations), have been proposed in the literature (without any intention of making an extensive review of the previous studies in these alloys, we can cite, for instance, references [15][16][17][18][19][20][21][22][23][24][25][26][27]). It should be mentioned that, despite localized spin Hamiltonians are not completely appropriate for the study of these metallic alloys, there are some experimental evidences and first principles calculations making possible the choice of localized models instead of the itinerant ones, as discussed, respectively, in Refs.…”