R. E. Camley, G. Leaf, H. Kaper, M. Yan, and M. Grimsditch, "Phase Transitions and Reversal Mechanisms in Nanosized Magnetic Bars: The Influence of Bulk and Localized Spin Wave Modes," Preprint ANL/MCS-P1359-0706, July 2006. [pdf]
Changes in symmetry of the magnetic groundstate of a Co bar as a function of an external field are found to be concomitant with soft spin excitations. The symmetry of the soft modes is found to predict the change in symmetry of the ground state, providing strong evidence that the soft modes are responsible for all the magnetic phase transitions observed in this system. Results are presented in which the Co bar reaches domain states with 3, 5, 12, and 13 domains. None of these states corresponds to the minimum energy state with six domains.