Broken symmetry states in FeSe_1-xS_x measured with STM/S

Strong electron correlations in cuprate high-temperature superconductors are known to be necessary for the emergence of exotic phases including and beyond superconductivity. Despite several phenomenological parallels between the cuprates and Fe-based superconductors, the degree to which strong correlations determine the phase diagram in the latter is uncertain. We used scanning tunneling microscopy and spectroscopy to investigate the local symmetries of the electronic states in FeSe_1-xS_x to search for possible signatures of strong correlations. An analysis of the energy dependence in our spectroscopic mappings, complemented by angle-resolved photoemission spectroscopy measurements and theoretical simulations, points to an electronic order that might originate from orbital-selective strong correlations.