Dirac nodal lines protected against spin-orbit interaction in IrO2

Abstract

Dirac semimetals have electrons that propagate in the solid as if they had no mass. In rutile iridium oxide IrO${}_{2}$, these unusual electronic states form lines in reciprocal space, which are protected by crystal symmetry against interactions such as spin-orbit coupling. In this work, the authors synthesized epitaxial films of IrO${}_{2}$ along two crystal orientations and used angle-resolved photoemission spectroscopy to reveal the existence of two Dirac nodal lines. These cross the Fermi level and therefore directly impact the low-energy properties of the material.