Violation of Hund’s third rule in structurally disordered ferromagnets

Violation of Hund’s third rule caused by structural disorder is observed for the induced magnetic moment of Zr, using X-ray magnetic circular dischroism. The induced spin and orbital magnetic moments are anti-parallel in the crystalline state, but parallel in an amorphous state of the investi- gated Co- and Fe-based materials. First principles calculations are used to provide physical insight into the dependency of the spin-orbit coupling on the interatomic distance and coordination number.