Metal-insulator transition in epitaxial perovskite SrIrO$_3$ thin films via strain

Iridates have drawn considerable interest due to their exotic phases arising from the interplay of the strong spin-orbit interaction and the electronic correlation. Here we will discuss our experimental investigations of the electronic properties of epitaxially strained SrIrO$_3$ thin-films. The orthorhombic perovskite crystal phase of SrIrO$_3$ is synthesized as a thin film ($\sim$ 20 nm) on various substrates of (LaAlO$_3$)$_{0.3}$-(Sr$_2$AlTaO$_6$)$_{0.7}$, SrTiO$_3$, GdScO$_3$, and MgO using pulsed laser deposition. We have observed that when the in-plane lattice parameters are tuned from tensile to compressive strain, the electronic behavior of the strained SrIrO$_3$ thin-films changes from metallic to insulating. All samples have sheet resistance below 13 k$\Omega$/$\Box$, and the insulating samples were fit using the Mott variable-range-hopping equation at low temperatures ($<$ 15 K), which is believed to be the conducing mechanism of Anderson localization at finite temperature. The strain-dependent metal-insulator transition in epitaxial perovskite SrIrO$_3$ thin-films offers an important insight into the electronic structure of these strongly correlated, spin-orbit-coupled materials.