arXiv subjects

Carlos. E. Fiore

Publications and source records attributed to Carlos. E. Fiore.

3 recordsLinked to original sources

arXiv2026

Universal features of nonequilibrium Ising models in contact with two thermal reservoirs

We derive generic properties of nonequilibrium phase transitions in all-to-all Ising models placed in contact with two thermal reservoirs, in which parameters (temperatures, interactions and field parameters) assume arbitrary values depending on the contact with each thermal bath. The presence of different kinds of external parameters leads to remarkably different sort of phase transitions. While continuous, discontinuous and even tricritical points are presented when external parameters are symmetric (e.g. the case of energetic barriers or different couplings between the system and thermal baths), the tricriticality is absent when external parameters are antisymmetric (e.g. the case of magnetic fields or biased drivings) implying that solely critical or discontinuous are possible. In such latter case, the probability distribution acquires the Boltzmann-Gibbs like form, irrespectively the model parameters when the switching between thermal reservoirs is sufficiently fast. Our work sheds light about the differences between equilibrium and nonequilibrium ingredients and theirs consequences upon phase transitions.

cond-mat.stat-mech↗

arXiv2016

Temporal disorder does not forbid discontinuous absorbing phase transitions in low dimensional systems

Distinct works have claimed that spatial (quenched) disorder can suppress the discontinuous absorbing phase transitions. Conversely, the scenario for temporal disorder for discontinuous absorbing phase transitions is unknown. In order to shed some light in this direction, we tackle its effect in three bidimensional examples, presenting undoubtedly discontinuous absorbing phase transitions. Except in one case (to be explained further), the temporal disorder is introduced by allowing the control parameter to be time dependent $p\rightarrow p(t)$ according to a uniform distribution of mean $p_0$ and width $σ$, in which at the emergence of the phase transition the system transits between active and absorbing regimes. In contrast to the spatial disorder, numerical results strongly suggest that temporal disorder does not forbid the existence of discontinuous transition. All cases are signed by behaviors similar to their pure (without disorder) counterparts, including bistability around the coexistence point and common finite size scaling behavior with the inverse of the system volume, as recently proposed in Phys. Rev. E. {\bf 92}, 062126 (2015). We also observe that temporal disorder does not induce temporal Griffiths phases around phase transitions, at least for $d=2$.

cond-mat.stat-mech↗

arXiv2012

Exploiting a semi-analytic approach to study first order phase transitions

In a previous contribution, Phys. Rev. Lett 107, 230601 (2011), we have proposed a method to treat first order phase transitions at low temperatures. It describes arbitrary order parameter through an analytical expression $W$, which depends on few coefficients. Such coefficients can be calculated by simulating relatively small systems, hence with a low computational cost. The method determines the precise location of coexistence lines and arbitrary response functions (from proper derivatives of $W$). Here we exploit and extend the approach, discussing a more general condition for its validity. We show that in fact it works beyond the low $T$ limit, provided the first order phase transition is strong enough. Thus, $W$ can be used even to study athermal problems, as exemplified for a hard-core lattice gas. We furthermore demonstrate that other relevant thermodynamic quantities, as entropy and energy, are also obtained from $W$. To clarify some important mathematical features of the method, we analyze in details an analytically solvable problem. Finally, we discuss different representative models, namely, Potts, Bell-Lavis, and associating gas-lattice, illustrating the procedure broad applicability.

cond-mat.stat-mech↗