Glassy dynamics, metastability limit and crystal growth in a lattice spin model

Center for Statistical Mechanics and Complexity, INFM Roma “La Sapienza” and Dipartimento di Fisica, Università di Roma “La Sapienza” - 00185 Roma, Italy

Received: 9 September 2002
Accepted: 14 October 2002

Abstract

We introduce a lattice spin model where frustration is due to multibody interactions rather than quenched disorder in the Hamiltonian. The system has a crystalline ground state and below the melting temperature displays a dynamic behaviour typical of fragile glasses. However, the supercooled phase loses stability at an effective spinodal temperature, and thanks to this the Kauzmann paradox is resolved. Below the spinodal the system enters an off-equilibrium regime corresponding to fast crystal nucleation followed by slow activated crystal growth. In this phase and in a time region which is longer the lower the temperature we observe a violation of the fluctuation-dissipation theorem analogous to structural glasses. Moreover, we show that in this system there is no qualitative difference between a locally stable glassy configuration and a highly disordered polycrystal.