Coherent manipulation of electronic order in a correlated insulator via sub-gap optical excitations*

Correlated transition-metal oxides allows for coherent manipulation of electronic order via sub-gap excitations through strong optical fields. Degeneracy between d-electron levels is often broken by the formation of local atomic moments. In nickel oxide, these moments order anti-ferromagnetic below about 525K. The magnetic ordering temperature is governed by the interatomic exchange-interaction, typically mediated through hybridization between nickel d-states and oxygen p-states. By upsetting the balance between Coulomb repulsion and kinetic effects with the strong electromagnetic fields of a sub-gap optical laser, we may influence the microscopic interactions governing electronic and magnetic order. The ability to influence Coulomb repulsion, as encompassed in the Hubbard U, and interatomic exchange is investigated. We conclude that the Hubbard U is robust even for fields up to 0.22V/Å, whereas exchange interactions may be modulated with sub-gap excitations, providing an avenue for coherent control of magnetic order.