Three-dimensional character of the Fermi surface in ultrathin LaTiO3/SrTiO3 heterostructures

LaTiO₃ films on SrTiO₃ single crystal substrates exhibit metallic behavior attributed to the LaTiO₃ film, the interface as well as part of the SrTiO₃. In the limit of ultrathin LaTiO₃ films on SrTiO₃, the contribution to the metallicity from strain-induced electronic structure modification of the LaTiO₃ film is minimized so that the dominant contribution to metallicity is from the interface and part of the SrTiO₃ due to charge transfer of 3 d electrons from LaTiO₃ to SrTiO₃. In such a limit, we observe quantum oscillations whose angular dependence indicates a three-dimensional Fermi surface. Such angular dependence is observed in two sets of quantum oscillations—one low frequency and one high frequency—that we have attributed to an inner and outer Fermi surface associated with a Rashba-like spin split hybridized d_{x z +y z} band.