Origin of Ising magnetism in Ca(3)Co(2)O(6) unveiled by orbital imaging

The one-dimensional cobaltate Ca[Formula: see text] Co[Formula: see text] O[Formula: see text] is an intriguing material having an unconventional magnetic structure, displaying quantum tunneling phenomena in its magnetization. Using a newly developed experimental method, [Formula: see text] -core-level non-resonant inelastic x-ray scattering ([Formula: see text] -NIXS), we were able to image the atomic Co [Formula: see text] orbital that is responsible for the Ising magnetism in this system. We can directly observe that corrections to the commonly accepted ideal prismatic trigonal crystal field scheme occur in Ca[Formula: see text] Co[Formula: see text] O[Formula: see text] , and it is the complex [Formula: see text] orbital occupied by the sixth electron at the high-spin Co[Formula: see text] ([Formula: see text] ) sites that generates the Ising-like behavior. The ability to directly relate the orbital occupation with the local crystal structure is essential to model the magnetic properties of this system.