title: Magnetic field controlled charge density wave coupling in underdoped YBa2Cu3O6+x.
abstract: The application of magnetic fields to layered cuprates suppresses their high-temperature superconducting behaviour and reveals competing ground states. In widely studied underdoped YBa2Cu3O6+x (YBCO), the microscopic nature of field-induced electronic and structural changes at low temperatures remains unclear. Here we report an X-ray study of the high-field charge density wave (CDW) in YBCO. For hole dopings ∼0.123, we find that a field (B∼10 T) induces additional CDW correlations along the CuO chain (b-direction) only, leading to a three-dimensional (3D) ordered state along this direction at B∼15 T. The CDW signal along the a-direction is also enhanced by field, but does not develop an additional pattern of correlations. Magnetic field modifies the coupling between the CuO2 bilayers in the YBCO structure, and causes the sudden appearance of the 3D CDW order. The mirror symmetry of individual bilayers is broken by the CDW at low and high fields, allowing Fermi surface reconstruction, as recently suggested.
authors.affiliation: Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Chang
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: E
authors.initials: E
authors.lastname: Blackburn
authors.affiliation: Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland.
authors.forename: O
authors.initials: O
authors.lastname: Ivashko
authors.affiliation: European Spallation Source ERIC, Box 176, Lund SE-221 00, Sweden.
authors.forename: A T
authors.initials: AT
authors.lastname: Holmes
authors.affiliation: Department of Physics, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark.
authors.forename: N B
authors.initials: NB
authors.lastname: Christensen
authors.affiliation: Condensed Matter Physics &Materials Science Department, Brookhaven National Lab, Upton, New York 11973, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hücker
authors.affiliation: Department of Physics &Astronomy, University of British Columbia, Vancouver V6T-1Z1, Canada.|Canadian Institute for Advanced Research, Toronto M5G-1Z8, Canada.
authors.forename: Ruixing
authors.initials: R
authors.lastname: Liang
authors.affiliation: Department of Physics &Astronomy, University of British Columbia, Vancouver V6T-1Z1, Canada.|Canadian Institute for Advanced Research, Toronto M5G-1Z8, Canada.
authors.forename: D A
authors.initials: DA
authors.lastname: Bonn
authors.affiliation: Department of Physics &Astronomy, University of British Columbia, Vancouver V6T-1Z1, Canada.|Canadian Institute for Advanced Research, Toronto M5G-1Z8, Canada.
authors.forename: W N
authors.initials: WN
authors.lastname: Hardy
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Rütt
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany.
authors.forename: M V
authors.initials: MV
authors.lastname: Zimmermann
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: E M
authors.initials: EM
authors.lastname: Forgan
authors.affiliation: H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK.
authors.forename: S M
authors.initials: SM
authors.lastname: Hayden