Eur. Phys. J. B (2015) 88: 160
https://doi.org/10.1140/epjb/e2015-60168-4

Regular Article

Role of initial correlation in coarsening of a ferromagnet

Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., 560064 Bangalore, India

^a e-mail: das@jncasr.ac.in

Received: 4 March 2015
Received in final form: 11 May 2015
Published online: 17 June 2015

Abstract

We study the dynamics of ordering in ferromagnets via Monte Carlo simulations of the Ising model, employing the Glauber spin-flip mechanism, in space dimensions d = 2 and 3, on square and simple cubic lattices. Results for the persistence probability and the domain growth are discussed for quenches to various temperatures (T_f) below the critical one (T_c), from different initial temperatures T_i ≥ T_c. In long time limit, for T_i>T_c, the persistence probability exhibits power-law decay with exponents θ ≃ 0.22 and ≃ 0.18 in d = 2 and 3, respectively. For finite T_i, the early time behavior is a different power-law whose life-time diverges and exponent decreases as T_i → T_c. The two steps are connected via power-law as a function of domain length and the crossover to the second step occurs when this characteristic length exceeds the equilibrium correlation length at T = T_i. T_i = T_c is expected to provide a new universality class for which we obtain θ ≡ θ_c ≃ 0.035 in d = 2 and ≃0.105 in d = 3. The time dependence of the average domain size ℓ, however, is observed to be rather insensitive to the choice of T_i.