Monoxides of small terbium clusters: A density functional theory investigation

To investigate the effect of oxygen atom on the geometrical structures, electronic, and magnetic properties of small terbium clusters, we carried out the first-principles calculations on Tb_nO (n = 1-14) clusters. The capping of an oxygen atom on one trigonal-facet of Tb_n structures is always favored energetically, which can significantly improve the structural stability. The far-infrared vibrational spectroscopies are found to be different from those of corresponding bare clusters, providing a distinct signal to detect the characteristic structures of Tb_nO clusters. The primary effect of oxygen atom on magnetic properties is to change the magnetic orderings among Tb atoms and to reduce small of local magnetic moments of the O-coordinated Tb atoms, both of which serve as the key reasons for the experimental magnetic evolution of an oscillating behavior. These calculations are consistent with, and help to account for, the experimentally observed magnetic properties of monoxide Tb_nO clusters [C. N. Van Dijk et al., J. Appl. Phys. 107, 09B526 (2010)]