title: Subband structure of a two-dimensional electron gas formed at the polar surface of the strong spin-orbit perovskite KTaO3.
abstract: We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the 5d transition-metal oxide KTaO3. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band structure and leads to a 2DEG composed of ladders of subband states of both light and heavy carriers. Despite the strong spin-orbit coupling, our measurements provide a direct upper bound for the potential Rashba spin splitting of only Δk(parallel)}~0.02 Å(-1) at the Fermi level. The polar nature of the KTaO3(100) surface appears to help mediate the formation of the 2DEG as compared to nonpolar SrTiO3(100).
authors.affiliation: SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife, United Kingdom.
authors.forename: P D C
authors.initials: PD
authors.lastname: King
authors.forename: R H
authors.initials: RH
authors.lastname: He
authors.forename: T
authors.initials: T
authors.lastname: Eknapakul
authors.forename: P
authors.initials: P
authors.lastname: Buaphet
authors.forename: S-K
authors.initials: SK
authors.lastname: Mo
authors.forename: Y
authors.initials: Y
authors.lastname: Kaneko
authors.forename: S
authors.initials: S
authors.lastname: Harashima
authors.forename: Y
authors.initials: Y
authors.lastname: Hikita
authors.forename: M S
authors.initials: MS
authors.lastname: Bahramy
authors.forename: C
authors.initials: C
authors.lastname: Bell
authors.forename: Z
authors.initials: Z
authors.lastname: Hussain
authors.forename: Y
authors.initials: Y
authors.lastname: Tokura
authors.forename: Z-X
authors.initials: ZX
authors.lastname: Shen
authors.forename: H Y
authors.initials: HY
authors.lastname: Hwang
authors.forename: F
authors.initials: F
authors.lastname: Baumberger
authors.forename: W
authors.initials: W
authors.lastname: Meevasana