Impact of structural transitions on electron transport at LaAlO3/SrTiO3 heterointerfaces

We have studied conductive LaAlO3/SrTiO3 heterostructures deposited at different oxygen pressures. Photoluminescence spectra confirm the presence of a significant amount of oxygen vacancies in samples deposited at low oxygen pressures. Power law fitting of resistance versus temperature measurements reveals fundamental characteristics of the conduction mechanism at the interface. A distinct non-Fermi-liquid behavior is observed for samples grown in higher oxygen pressure, which give two-dimensionally confined conducting interfaces, whereas characteristic electron-electron scattering is observed for samples grown in lower oxygen pressures, as seen in bulk doped SrTiO3 (i.e., oxygen deficient SrTiO3). Transitions between different conduction modes occur throughout the studied temperature range (10-270 K) as a result of structural transformations in the near-surface region of the SrTiO3. (C) 2012 American Institute of Physics. [doi:10.1063/1.3687706]