Transition order and dynamics of a model with competing exchange and dipolar interactions

• Published in: Journal of magnetism and magnetic materials 2009-02, Vol.321 (3), p.137-143
• Main Authors: JOKNYS, A, TORNAU, E. E
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical-point effects, specific heats, short-range order; Exact sciences and technology; Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.); Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Physics; Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2008.08.048

We performed Monte Carlo simulation of phase transitions from isotropic stripe phase with short-range order to long-range stripe phase in a model with competing ferromagnetic exchange and antiferromagnetic dipolar interactions on triangular lattice. We calculated phase diagram for different values of exchange and dipolar interaction constants ratio, eta. We also determined the order of the transitions to stripe phases AFh of different stripe widths h: first-order phase transition was found to transitions into AF1 and AF2 phases, while transitions to AF3 and AF4 phases were of the second order. In the phase diagram the tricritical point was determined at the AF2 and AF3 phase boundary. We observed the peak of nematic phase at the transition region to the AF1 phase, but found it metastable at low values of eta. We have also found that in AF1 phase spin relaxation corresponds to the Ising model dynamics. In phases AF3 and AF4 the dynamics slows down, and stripe domain growth with time is proportional to logt.