Magnetic excitations probed by resonant inelastic soft x-ray scattering from high-Tc superconducting cuprates

Recently, due to the experimental improvement of the energy resolution, the resonant inelastic scattering (RIXS) spectra originated from the magnetic excitations have been reported at the Cu L-edge from the high-Tc superconducting cuprates. In undoped systems, it is found that the energy profile of RIXS spectrum brought about by the magnon excitation varies its shape depending on the wave number of x-ray. Quite recently, the similar excitation spectra have been reported from the superconducting phase, which are interpreted as the consequence of the paramagnon excitation. A microscopic theory of RIXS accounting for the magnetic excitation developed by the present authors is explained, which is beyond the fast collision approximation. (author)