Distortion Analysis of Ir- and Co-doped LaAlO^sub 3^/SrTiO^sub 3^ (001) Interfaces by Hard X-ray Photoelectron Diffraction

The structural distortions at LaAlO3/SrTiO3 (001) interfaces doped with Ir or Co have been studied by hard X-ray photoelectron diffraction (HXPD). In this work, HXPD at a photon energy of 7940 eV was used for studying the buried interfaces. The magnitude of lattice strain perpendicular to the interface in the LaAlO3 layer of Ir- or Co-doped LaAlO3/SrTiO3 heterostructure was estimated from forward focusing peak shift. The largest strain was found in a 3% Ir-doped sample while the strain was negligibly small in a 5% Ir-doped sample due to strong Ir interdiffusion. A similar decrease of the out-of-plane strain at higher doping concentration was not seen in Co-doped samples. This difference is attributed to the different ionic radii of Co and Ir.