Strain-induced nonsymmorphic symmetry breaking and removal of Dirac semimetallic nodal line in an orthoperovskite iridate

Abstract

By using a combination of heteroepitaxial growth, structure refinement based\non synchrotron x-ray diffraction and first-principles calculations, we show\nthat the symmetry-protected Dirac line nodes in the topological semimetallic\nperovskite SrIrO3 can be lifted simply by applying epitaxial constraints. In\nparticular, the Dirac gap opens without breaking the Pbnm mirror symmetry. In\nvirtue of a symmetry-breaking analysis, we demonstrate that the original\nsymmetry protection is related to the n-glide operation, which can be\nselectively broken by different heteroepitaxial structures. This symmetry\nprotection renders the nodal line a nonsymmorphic Dirac semimetallic state. The\nresults highlight the vital role of crystal symmetry in spin-orbit-coupled\ncorrelated oxides and provide a foundation for experimental realization of\ntopological insulators in iridate-based heterostructures.\n