arXiv subjects

Francisco Dinóla Neto

Publications and source records attributed to Francisco Dinóla Neto.

2 recordsLinked to original sources

arXiv2018

Ferromagnetic phases due to competing short- and long-range interactions in the spin-S Blume-Capel model

We broaden the study of the statistical physics of the spin-$S$ Blume-Capel model with ferromagnetic mean-field interactions $J$ in competition with short-range antiferromagnetic interactions $K$ in a linear chain in the thermodynamic limit. This work describes the critical behavior of the model when the $S$ takes a half integer and an integer value. In both cases the phase diagrams exhibit new ferromagnetic phases (for certain values of $K$) enclosed by branches emerging from the first-order frontiers of the pure ferromagnetic model. For finite temperatures the complex topologies were obtained by numerical minimization of the free energy.

cond-mat.stat-mech↗

arXiv2018

First-order phase transition by a spin-flip potential in BCS superconductivity

A spin-flip potential $V$ is introduced in a BCS Hamiltonian in order to study a possible thermodynamic effect that might be caused by the addition of a magnetic impurity in a superconductor. We found that the competition between the pairing and the spin-flip effect, caused by the interaction between the itinerant electrons and the spin of the impurity, gives rise to a first-order phase transition for certain values of $V$. The phase diagram shows a tricritical point in a frontier line which is topologically similar to those found in the phase diagrams of some Ising-like models.

cond-mat.stat-mech↗