We investigated the effect of intermolecular dipolar interactions on an ensemble of 100 three-dimensional systems of 5�5�4 nanomagnets, each with spin S=5, arranged in a cubic lattice. We employed the Landau-Lifshitz-Gilbert equation to solve for the magnetization curves for several values of the damping constant, the induction sweep rate, the lattice constant, the temperature, and the magnetic anisotropy. We find that the smaller the damping constant, the stronger the maximum induction required to produce hysteresis. The shape of the hysteresis loops also depends on the damping constant. We find further that the system magnetizes and demagnetizes at decreasing magnetic field strengths with decreasing sweep rates, resulting in smaller hysteresis loops. Variations of the lattice constant within realistic values (1.52.5 nm) show that the …

This work has been reported on the Physical Review B [M. Alcantara Ortigoza, R. A. Klemm, and T. S. Rahman, Phys. Rev. B 72, 174416 (2005)]