Origin of Ising magnetism in Ca3Co2O6 unveiled by orbital imaging

TL;DR

This paper uses a novel x-ray scattering technique to directly image the specific Co 3d orbital responsible for Ising magnetism in Ca3Co2O6, revealing the orbital origin of its magnetic behavior.

Contribution

It introduces a new experimental method, s-NIXS, to directly observe the orbital responsible for magnetism in a transition metal compound.

Findings

Direct imaging of the Co 3d orbital responsible for magnetism.

Identification of the complex d2 orbital at high-spin Co3+ sites.

Linking orbital occupation with local crystal structure.

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 3d orbital that is responsible for the Ising magnetism in this system. We show that we can directly observe that it is the complex d2 orbital occupied by the sixth electron at the high-spin Co-trig{3+} (d6) sites that generates this behavior. This is extremely rare in the research field of transition metal compounds, and is only made possible by the delicately balanced prismatic trigonal coordination. The ability to directly relate the orbital occupation with the local crystal structure is essential to model the magnetic properties of this system.