  Perovskite SrIrO3 (SIO) films epitaxially deposited with a thickness of about
60 nm on various substrate materials display nearly strain-relieved state.
Films 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. Resistance measurements on the SIO
films reveal only weak temperature dependence, where the resistance R increases
with decreasing temperature T. Hall measurements show dominant electron-like
transport throughout the temperature range from 2 K to 300 K. At 2 K, the
electron concentration and resistivity for SIO on STO amount to ne = 1.4*10^20
cm-3 and 1 mohmcm. 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. The anisotropy of the resistance
increases with decreasing T and displays a distinct maximum around 86 K. The
specific T-dependence is similar to that of the structural anisotropy
sqrt(a2+b2)/c of bulk SIO. Therefore, anisotropic electronic transport in SIO
is very likely induced by the orthorhombic distortion. Consequently, for
twinned SIO films on STO anisotropy vanishes nearly completely. The
experimental results show that structural changes are very likely responsible
for the observed anisotropic electronic transport. The strong sensitivity of
the electronic transport in SIO films may be explained in terms of the narrow
electron-like bands in SIO caused by spin-orbit-coupling and orthorhombic
distortion.
