Volume 79, Number 5, September 2007
Article Number 56002
Number of page(s) 6
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 01 August 2007
EPL, 79 (2007) 56002
DOI: 10.1209/0295-5075/79/56002

Nonequilibrium critical relaxation at a first-order phase transition point

M. Pleimling1 and F. Iglói2, 3

1  Department of Physics, Virginia Polytechnic Institute and State University - Blacksburg, VA 24061-0435, USA
2  Research Institute for Solid State Physics and Optics - H-1525 Budapest, Hungary
3  Institute of Theoretical Physics, Szeged University - H-6720 Szeged, Hungary

received 14 May 2007; accepted in final form 13 July 2007; published September 2007
published online 1 August 2007

We study numerically the nonequilibrium dynamical behavior of an Ising model with mixed two-spin and four-spin interactions after a sudden quench from the high-temperature phase to the first-order phase transition point. The autocorrelation function is shown to approach its limiting value, given by the magnetization in the ordered phase at the transition point, mc, through a stretched exponential decay. On the other hand relaxation of the magnetization starting with an uncorrelated initial state with magnetization, mi, approaches either mc, for mi > 0.5, or zero, for mi < 0.5. For small mi and for mi slightly larger than 0.5 the relaxation of the magnetization shows an asymptotic power law time dependence, thus from a nonequilibrium point of view the transition is continuous.

64.60.Ht - Dynamic critical phenomena .
75.40.Gb - Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.) .
05.70.Fh - Phase transitions: general studies .

© Europhysics Letters Association 2007