Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

In-plane anisotropic ground states are ubiquitous in correlated solids such as pnictides1, cuprates2 and manganites3. They arise naturally from doping Mott insulators4 and compete with phases such as superconductivity5. However, strong coupling between lattice, charge, orbital and spin degrees of freedom results in simultaneous ordering of multiple parameters, masking the mechanism that drives the anisotropy6. We demonstrate that orbital domains in a manganite can be oriented by the polarization of an external pulsed THz light field. The THz control field non-resonantly couples to electrons, indicating that Coulomb interactions are the primary driving factor for the orbital order. Field control is explained by a simple Hubbard model that shows the force on the domain originates from the Coulomb interaction. Our results demonstrate the key role played by charge localization in driving orbital order in manganites and show how THz can be utilized in new ways to understand and manipulate anisotropic phases in a broad range of correlated materials.