Detect the orbital distribution of the magnetic fluctuation in the Iron-based superconductors with resonant inelastic X-ray scattering spectroscopy

Detecting the orbital distribution of the magnetic fluctuation of the Iron-based superconductors is the key to understand the mechanism for the magnetism, superconductivity and electronic nematicity in these multi-orbital systems. In this work, we propose that the resonant inelastic X-ray scattering(RIXS) technique can be used to probe selectively the magnetic fluctuation on different Fe $3d$ orbitals. In particular, the magnetic fluctuation on the three $t_{2g}$ orbitals, namely $3d_{xz}$, $3d_{yz}$ and $3d_{xy}$, can be probed separately by arranging properly the polarization of the incident and outgoing photons. Such orbital-resolved information on the magnetic fluctuation is invaluable for the study of the orbital-selective manifestation of electron correlation effect and the entanglement between the orbital and the magnetic degree of freedom in the electronic nematic phase of the iron-based superconductors.