Eur. Phys. J. E (2017) 40: 94
https://doi.org/10.1140/epje/i2017-11583-7

Regular Article

Universality of domain growth in antiferromagnets with spin-exchange kinetics

¹ School of Physical Sciences, Jawaharlal Nehru University, 110067, New Delhi, India
² S. N. Bose National Centre for Basic Sciences, 700098, Kolkata, India

^* e-mail: purijnu@gmail.com

Received: 22 April 2017
Accepted: 23 October 2017
Published online: 8 November 2017

Abstract

We study phase ordering kinetics in symmetric and asymmetric binary mixtures, undergoing an order-disorder transition below the critical temperature. Microscopically, we model the kinetics via the antiferromagnetic Ising model with Kawasaki spin-exchange kinetics. This conserves the composition while the order parameter (staggered magnetization) is not conserved. The order-parameter correlation function and structure factor show dynamical scaling, and the scaling functions are independent of the mixture composition. The average domain size shows a power-law growth: . The asymptotic growth regime has , though there can be prolonged transients with for asymmetric mixtures. Our unambiguous observation of the asymptotic universal regime is facilitated by using an accelerated Monte Carlo technique. We also obtain the coarse-grained free energy from the Hamiltonian, as a function of two order parameters. The evolution of these order parameters is modeled by using Model C kinetics. As for the microscopic dynamics, the average domain size of the nonconserved order-parameter (staggered magnetization) field exhibits a power-law growth: at later times, irrespective of the mean value of the conserved order-parameter (composition) field.