Magnetic Excitations in CoO(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

概要

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Magnetic excitations in CoO below T_N=289K were investigated on single crystals and a powder specimen by using inelastic neutron-scattering spectrometers installed at a steady state neutron-source and a pulsed neutron source. In single-crystal data, dispersion relations of the two magnetic excitation modes below 70meV were determined along the symmetric directions. The magnetic excitations around 120meV were also observed. Energy spectra on a powder specimen suggest the existence of higher order magnetic excitations spreading up to around 200meV. The magnetic modes were analyzed in connection with the freedom of an unquenched orbital angular-momentum L of a Co^<2+> ion. The magnitude of the spin-orbit interaction and that of the exchange interaction obtained from the analyses are comparable, indicating that those interactions must be simultaneously considered without an approximation of the total-angular-momentum. The lowest two dispersion curves are interpreted as mixing and splitting between a dispersive excitation of S_z(5-mode) and an individual excitation of L_z(L-mode). The present experiments are the first observation of such hybridization of the S-mode and the L-mode.
社団法人日本物理学会の論文
2006-08-15