Europhys. Lett.
Volume 74, Number 1, April 2006
Page(s) 89 - 95
Section Condensed matter: structural, mechanical and thermal properties
Published online 22 February 2006
Europhys. Lett., 74 (1), pp. 89-95 (2006)
DOI: 10.1209/epl/i2005-10500-9

Critical aging of a ferromagnetic system from a completely ordered state

A. A. Fedorenko and S. Trimper

Fachbereich Physik, Martin-Luther-Universität Halle-Wittenberg D-06099 Halle, Germany

received 9 December 2005; accepted in final form 3 February 2006
published online 22 February 2006

We adapt the nonlinear $\sigma$ model to study the nonequilibrium critical dynamics of $\ab{O}(n)$ symmetric ferromagnetic system. Using the renormalization group analysis in $d=2+\varepsilon$ dimensions we investigate the pure relaxation of the system starting from a completely ordered state. We find that the average magnetization obeys the long-time scaling behaviour almost immediately after the system starts to evolve while the correlation and response functions demonstrate scaling behaviour which is typical for aging phenomena. The corresponding fluctuation-dissipation ratio is computed to first order in $\varepsilon$ and the relation between transverse and longitudinal fluctuations is discussed.

64.60.Ht - Dynamic critical phenomena.
05.70.Ln - Nonequilibrium and irreversible thermodynamics.

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