Numerical simulations based on the stochastic Langevin equation are applied here to a system of two uniaxial single domain ferromagnetic particles with antiferromagnetic dipolar coupling. The hysteresis loops of a strongly coupled systems exhibit fully demagnetized, intermediate metastable configurations which separate the two fully saturated states. At small magnetostatic couplings, on the other hand, and at sufficiently weak damping, the intermediate metastable configuration becomes only partially demagnetized. This state cannot be associated with any single local minimum of the free energy function.
Journal of Applied Physics
J. Appl. Phys. 109, 07D339 (2011)