title: Tailoring the nature and strength of electron-phonon interactions in the SrTiO3(001) 2D electron liquid.
abstract: Surfaces and interfaces offer new possibilities for tailoring the many-body interactions that dominate the electrical and thermal properties of transition metal oxides. Here, we use the prototypical two-dimensional electron liquid (2DEL) at the SrTiO3(001) surface to reveal a remarkably complex evolution of electron-phonon coupling with the tunable carrier density of this system. At low density, where superconductivity is found in the analogous 2DEL at the LaAlO3/SrTiO3 interface, our angle-resolved photoemission data show replica bands separated by 100 meV from the main bands. This is a hallmark of a coherent polaronic liquid and implies long-range coupling to a single longitudinal optical phonon branch. In the overdoped regime the preferential coupling to this branch decreases and the 2DEL undergoes a crossover to a more conventional metallic state with weaker short-range electron-phonon interaction. These results place constraints on the theoretical description of superconductivity and allow a unified understanding of the transport properties in SrTiO3-based 2DELs.
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Z
authors.identifier: 0000-0002-4854-2170
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: McKeown Walker
authors.affiliation: Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: A
authors.identifier: 0000-0001-5239-6826
authors.initials: A
authors.lastname: Tamai
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.|Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Z
authors.initials: Z
authors.lastname: Ristic
authors.affiliation: Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: F Y
authors.identifier: 0000-0002-3970-8837
authors.initials: FY
authors.lastname: Bruno
authors.affiliation: Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: de la Torre
authors.affiliation: Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Riccò
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: N C
authors.identifier: 0000-0002-2334-8494
authors.initials: NC
authors.lastname: Plumb
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Shi
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, 12489 Berlin, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Hlawenka
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, 12489 Berlin, Germany.
authors.forename: J
authors.identifier: 0000-0001-9947-6700
authors.initials: J
authors.lastname: Sánchez-Barriga
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, 12489 Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Varykhalov
authors.affiliation: Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK.
authors.forename: T K
authors.identifier: 0000-0003-4201-4462
authors.initials: TK
authors.lastname: Kim
authors.affiliation: Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK.
authors.forename: M
authors.initials: M
authors.lastname: Hoesch
authors.affiliation: SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK.
authors.forename: P D C
authors.identifier: 0000-0002-6523-9034
authors.initials: PD
authors.lastname: King
authors.affiliation: School of Physics and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
authors.forename: W
authors.initials: W
authors.lastname: Meevasana
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: U
authors.initials: U
authors.lastname: Diebold
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.|Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Mesot
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: B
authors.identifier: 0000-0002-3747-8484
authors.initials: B
authors.lastname: Moritz
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.|Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Devereaux
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Radovic
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.|Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.|SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK.
authors.forename: F
authors.identifier: 0000-0001-7104-7541
authors.initials: F
authors.lastname: Baumberger