Measurement of the effect of lattice strain on magnetic interactions and orbital splitting in CaCuO2 using resonant inelastic x-ray scattering

The energy of magnetic and orbital excitations of copper-oxide systems have been assessed in bulk materials, but little is known about how they change in thin films or heterostructures. Although in these samples the epitaxial strain is known to alter important physical properties, such as T-c, the actual relation to fundamental excitations remains to be established. Here we determine how the magnetic interactions and orbital splitting scale with lattice constant under strain in the prototypical insulating cuprate CaCuO2. We extract the scaling power laws both experimentally, using Cu L-3 resonant inelastic x-ray scattering, and theoretically, with ab initio quantum chemical calculations. This combined approach quantifies the large impact of small lattice variations on the magnetic and orbital energy scales and opens the way to the production of strain-engineered samples. DOI: 10.1103/PhysRevB.87.085124