We present a modified two-dimensional random-field Ising model, where a dipolar interaction term is added to the classic random-field Hamiltonian. In a similar model it was already verified that the system state can exhibit domains in the form of stripe patterns, typical of thin materials with strong perpendicular anisotropy. In this work we show that the hysteresis loops obtained at zero temperature can display a strict similarity with the loops obtained in thin magnetic materials such as garnet films. In our model the processes of domain nucleation and domain-wall motion are well separated in time as the system evolves. This remarkable fact allowed us to better understand the nucleation process in this family of spin systems.

• Received 16 July 1998

DOI:https://doi.org/10.1103/PhysRevB.59.985