Origin of Ising magnetism in Ca3Co2O6 unveiled by orbital imaging

Abstract

The one-dimensional cobaltate Ca3Co2O6 is an intriguing material having an unconventional magnetic structure, displaying quantum tunneling phenomena in its magnetization. Using a newly developed experimental method, s-core-level non-resonant inelastic x-ray scattering (s-NIXS), we were able to image the atomic Co 3 d 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 Ca3Co2O6, and it is the complex d2 orbital occupied by the sixth electron at the high-spin Cotrig3+ (d6) 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.