Slow dynamics of Ising models with energy barriers

Using Monte Carlo simulations we study the dynamics of three-dimensional Is ing models with nearest-, next-nearest-, and four-spin (plaquette) interact ions. During coarsening, such models develop growing energy barriers, which leads to very slow dynamics at low temperature. As already reported, the m odel with only the plaquette interaction exhibits some of the features char acteristic of ordinary glasses: strong metastability of the supercooled liq uid, a weak increase of the characteristic length under cooling, stretched- exponential relaxation, and aging. The addition of two-spin interactions, i n general, destroys such behavior: the liquid phase loses metastability and the slow-dynamics regime terminates well below the melting transition, whi ch is presumably related with a certain corner-rounding transition. However , for a particular choice of interaction constants, when the ground state i s strongly degenerate, our simulations suggest that the slow-dynamics regim e extends up to the melting transition. The analysis of these models leads us to the conjecture that in the four-spin Ising model domain walls lose th eir tension at the glassy transition and that they are basically tensionles s in the glassy phase.