-electron states in NdB

Metoki, Naoto   ; Yamauchi, Hiroki   ; Watanuki, Ryuta*; Kawamura, Seiko   ; Yoshida, Masahiro*; Yoshizawa, Hideki*

NdB has a crystal structure with two-dimensional orthogonal dimers that are expected to be geometrically frustrated. In the magnetic ordered phase, magnetic moment has a complex structure in which orthogonal in-plane components and a weak c-axis component are induced. To clarify the ordering mechanism and order parameter, we focused on the electronic state and carried out inelastic neutron scattering experiments on this system. In the paramagnetic state, we found a quasi-doublet state associated with a strong uniaxial crystal field, which can be explained by the entropy released with successive transitions. In addition, in the ordered phase, a peak shift and splitting into four singlets were observed. We analyzed the temperature dependence of the spectrum considering with magnetic and quadrupolar interactions and their coupling terms. The results can well explain the mechanism of the transition, which we will show in this presentation.