Spin Dynamics in NaV 2O 5 – Inelastic Neutron Scattering

Inelastic neutron scattering measurement of NaV 2 O 5 single crystal samples was carried out to measure their magnetic excitations in the spin-Peierls dimerized state. We found a steep dispersion along the b * -axis (chain direction), having a spin-Peierls gap of almost 10 meV at (3, 0.5, 0). Along the a * -axis (interchain direction), two excitation modes with a weak dispersion have been observed. In addition, a novel intensity modulation has been discovered along this direction, which has not been expected from the crystal structure reported so far.