Spin Dynamics and Resonant Inelastic X-ray Scattering in Chromium with Commensurate Spin-Density Wave Order

摘要

We theoretically investigate spin dynamics and $L_3$-edge resonant inelasticX-ray scattering (RIXS) of Chromium with commensurate spin-density wave (SDW)order, based on a multi-band Hubbard model composed of 3$d$ and 4$s$ orbitals.Obtaining the ground state with the SDW mean-field approximation, we calculatethe dynamical transverse and longitudinal spin susceptibility by usingrandom-phase approximation. We find that a collective spin-wave excitation seenin inelastic neutron scattering hardly damps up to $\sim$0.6 eV. Above theenergy, the excitation overlaps individual particle-hole excitations asexpected, leading to broad spectral weight. On the other hand, the collectivespin-wave excitation in RIXS spectra has a tendency to be masked by largespectral weight coming from particle-hole excitations with various orbitalchannels. This is in contrast with inelastic neutron scattering, where onlyselected diagonal orbital channels contribute to the spectral weight. However,it may be possible to detect the spin-wave excitation in RIXS experiments inthe future if resolution is high enough.