title: Electric-field-induced polar order and localization of the confined electrons in LaAlO3/SrTiO3 heterostructures.
abstract: With ellipsometry, x-ray diffraction, and resistance measurements we investigated the electric-field effect on the confined electrons at the LaAlO3/SrTiO3 interface. We obtained evidence that the localization of the electrons at negative gate voltage is induced, or at least enhanced, by a polar phase transition in SrTiO3 which strongly reduces the lattice polarizability and the subsequent screening. In particular, we show that the charge localization and the polar order of SrTiO3 both develop below ∼50  K and exhibit similar, unipolar hysteresis loops as a function of the gate voltage.
authors.affiliation: University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Musée 3, CH-1700 Fribourg, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Rössle
authors.forename: K W
authors.initials: KW
authors.lastname: Kim
authors.forename: A
authors.initials: A
authors.lastname: Dubroka
authors.forename: P
authors.initials: P
authors.lastname: Marsik
authors.forename: C N
authors.initials: CN
authors.lastname: Wang
authors.forename: R
authors.initials: R
authors.lastname: Jany
authors.forename: C
authors.initials: C
authors.lastname: Richter
authors.forename: J
authors.initials: J
authors.lastname: Mannhart
authors.forename: C W
authors.initials: CW
authors.lastname: Schneider
authors.forename: A
authors.initials: A
authors.lastname: Frano
authors.forename: P
authors.initials: P
authors.lastname: Wochner
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.forename: B
authors.initials: B
authors.lastname: Keimer
authors.forename: D K
authors.initials: DK
authors.lastname: Shukla
authors.forename: J
authors.initials: J
authors.lastname: Strempfer
authors.forename: C
authors.initials: C
authors.lastname: Bernhard