Electric Multipole Transitions of Resonant X-ray Scattering for Studying Orbital Specific Magnetization in TmB 4

Strongly intertwined interaction among spin, orbital and charge degrees of freedom is the essence to induce emergent materials properties, and the investigation to understand their interplay has been actively pursued. In particular, resonant X-ray scattering technique has demonstrated powerful applications in unveiling their long-range ordering behavior with its enhanced sensitivity to the aforementioned degree of freedom. Here, we further demonstrated the spectroscopic application of the technique by providing experimental evidence to reveal spin polarizations in 4 f and 5 d orbital of the magnetic Tm ions with the orbital-selectivity, which introduced a route to understand fundamental mechanism of spin polarization in the compound. The enhanced sensitivity of the resonant X-ray scattering to various electric multipole transitions expects to find strong applications in studying various spin and polar ordering in materials to include high-order moments.