Growth of high-quality perovskite (110)-SrIrO₃ thin films using reactive molecular beam epitaxy

Recently, 5d transition metal iridates have been reported as promising materials for the manufacture of exotic quantum states. Apart from the semimetallic ground states that have been observed, perovskite SrIrO₃ is also predicted to have a lattice-symmetrically protected topological state in the (110) plane due to its strong spin-orbit coupling and electron correlation. Compared with non-polar (001)-SrIrO₃, the especial polarity of (110)-SrIrO₃ undoubtedly adds the difficulty of fabrication and largely impedes the research on its surface states. Here, we have successfully synthesized high-quality (110)-SrIrO₃ thin films on (110)-SrTiO₃ substrates by reactive molecular beam epitaxy for the first time. Both reflection high-energy electron diffraction patterns and x-ray diffraction measurements suggest the expected orientation and outstanding crystallinity. A (1×2) surface reconstruction driven from the surface instability, the same as that reported in (110)-SrTiO₃, is observed. The electric transport measurements uncover that (110)-SrIrO₃ exhibits a more prominent semimetallic property in comparison to (001)-SrIrO₃.