Magnetic and Orbital Ordering of KCuF$_{3}$ Studied by Soft X-ray Scattering

The interplay between charge, orbital, and spin degrees of freedom plays an important role in the underlying physics of transition-metal compounds. The charge-transfer insulator KCuF$_{3}$ is an archetype of orbitally ordered materials with large exchange interaction energy. KCuF$_{3}$ has long been known to display quantum one-dimensional antiferromagnetic properties along the $c$-axis originating from the superexchange interaction between the $e_g$ orbitals of Cu$^{2+}$. Due to the large Jahn-Teller distortion in the tetragonal structure, the degeneracy of the two $e_g$ orbitals is lifted and the $e_g$ orbitals form a pattern of orbital ordering . In this talk, we will present our recent measurements of spin and orbital ordering of KCuF$_{3}$ by soft X-ray scattering to address its magnetic transition and the coupling between spin and orbital degrees of freedom.