Emergent Phenomena at Mott Insulator/ Band Insulator Interfaces*

Complex oxide interfaces have been explored extensively in recent years as emergent phenomena, ranging from magnetism, metallicity, superconductivity to spin-orbit coupling, have been generated at these interfaces due to electronic, magnetic, orbital reconstruction etc. Electronic reconstruction at a Mott insulator/ band insulator interface has been predicted to exhibit a wide range of emergent electronic and magnetic behavior. A particularly interesting model system is the LaTiO₃/ SrTiO₃ interface where electronic reconstruction gives rise to low dimensional metallic behavior accompanied by giant Rashba spin-orbit coupling. We studied ultrathin films of LaTiO₃ on SrTiO₃ substrates where interface reconstruction dominates the transport behavior. We found evidence for giant Rashba spin splitting in two sets of Shubnikov-de Haas oscillations associated with an inner and outer Fermi surface, Berry phase of π, substantial anisotropic magnetoresistance and a weak anti-localization correction to the magnetoconductivity. Together these results indicate a large Rashba coupling coefficient of 2.0 x 10^-11 eV-m which is an order of magnitude larger than other complex oxide interfaces. Such a large Rashba coupling suggests that such a Mott/band insulator interface may be an excellent candidate for spin current-based electronics.