Dynamical phase transitions and spin glasses

A. P. Young

A Correspondent

Theo M. Nieuwenhuizen, Félix Ritort

Deepak Kumar

Avidan Uriel Neumann, Bernard Derrida

We study the time evolution of two configurations submitted to the same thermal noise for several two dimensional models (Ising ferromagnet, symmetric spin glass, non symmetric spin glass). For all these models, we find a non zero critical temperature above which the two configurations always meet. Using finite size scaling ideas, we determine for these three models this dynamical phase transition and some of the critical exponents. For the ferromagnet, the transition Tc ≃ 2.25 coincides with the Curie temperature whereas for the two spin glass models ( ± J distribution of bonds) we obtain Tc ≃ 1.5-1.7.

Francisco A. Tamarit, Evaldo M. F. Curado

The dynamical behaviour of the van Hemmen model of spin glass is studied by comparing the time evolution of two configurations subjected to the same thermal noise. It was found that the system undergoes several dynamical phase transitions among the paramagnetic, ferromagnetic, spin-glass and mixed phases, The dynamical phase diagram seems to be in good agreement with the static one. In the spin glass phase, the system presents a quite different dynamical behaviour from that found in short-range spin glass models as well as in the Sherrington-Kirkpatrick model.