Review of Spin–Orbit Coupled Semimetal SrIrO₃in Thin Film Form

Spin–orbit coupling, locking the momentum of an electron to its spin, has been shown essential for giving rise to many novel physical behaviors. SrIrO3 is a typical metallic member of the strong spin–orbit coupling iridate family. Its orthorhombic phase has been confirmed as a paramagnetic semimetal resulted from the interplay among spin–orbit coupling, electron correlation, and crystal field, and was theoretically predicted to host versatile topological phases. This article reviews the current knowledge on the preparation and the tunable properties of orthorhombic SrIrO3 films. Experiments have demonstrated that orthorhombic SrIrO3 can be successfully synthesized as films under substrate lattice constraint without high pressure, and the films frequently display metal-insulator transition due to disorder and weak-antilocalization owing to spin-orbit coupling. The properties of orthorhombic SrIrO3 film are sensitive to the rotation and tilting of the IrO6 octahedral, and consequently can be significantly tuned through strain engineering. Simultaneously, thickness-dependent size effect is also remarkable in SrIrO3 films. The accumulated research on SrIrO3 films suggests an urgent demand for research on superlattices constructed with orthorhombic SrIrO3, to better understand the mechanism of the electron structure evolution, and thus the relevant magnetic states and topological phases in orthorhombic SrIrO3 and its family.