Raman imaging of ferroelastically configurable Jahn-Teller domains in LaMnO3

The Jahn-Teller (JT) effect, through geometric deformation of molecules or local ionic lattices, lowers the overall energy of the system by removing electron degeneracy from partially occupied orbitals. Crystal symmetry lowered by JT distortion inevitably creates multiple variants of elastic and orbital-anisotropic states. Visualization and control of the domain/wall textures create a cornerstone to understand various correlated phenomena and explore wall properties. Here, we report the real-space observation of JT phonon and orbiton-related domains in a LaMnO3 thin film using confocal Raman spectromicroscopy. The characteristic symmetries of the JT-originated Raman modes allow us to detect and visualize the local population and orientation of the JT planes. Combined with a crystal structural analysis, we find that the formation of ferroelastic domains with W or W' walls provides the basic framework for understanding JT domain textures. Furthermore, we demonstrate the JT domains can be manipulated by applying local external stress. Our findings provide a useful pathway for mechanically-tunable orbitronic applications.