SFB Colloquium

The strong spin-orbit-coupling (SOC) in 5d iridium-based transition-metal oxides results in comparable energy scales of the electron correlation, electronic bandwidth, and SOC, which makes these materials promising candidates for the emergence of new topological phenomena or quantum states. However, the metastable form of SrIrO₃ (SIO) prevents single-crystal growth under ambient pressure, where only the monoclinic modification with C2/2 (15) dominates the ambient phase. Nevertheless, SIO can be successfully synthesized in polycrystalline form under pressure or stabilized by the epitaxial growth of thin films. Therefore, epitaxially grown SIO films are of current interest to explore the system. In addition, SIO films might act as a key building block for engineering topological phases at interfaces and in heterostructures.

Here, we will report on the film preparation electronic transport measurements of SIO films. Films with a thickness of about 60 nm grown on orthorhombic (110) DyScO₃ (DSO) are found to display untwinned bulk-like orthorhombic structure. However, film deposition on cubic (001) SrTiO₃ induces a twinned growth of SIO. Hall measurements show dominant electron-like transport throughout the temperature range from 2 K to 300 K. Interestingly, the film resistance of untwinned SIO on DSO along the [1-10] and the [001] direction differs by up to 25% indicating pronounced anisotropic electronic transport very likely induced by the orthorhombic distortion. The anisotropic electronic behavior appears to be extraordinary sensitive to octahedral distortion induced by epitaxial growth and uniaxial or hydrostatic pressure. The strong sensitivity of the electronic transport may be explained in terms of the narrow electron-like bands in SIO caused by spin-orbit-coupling and orthorhombic distortion.