title: Direct evidence for charge stripes in a layered cobalt oxide.
abstract: Recent experiments indicate that static stripe-like charge order is generic to the hole-doped copper oxide superconductors and competes with superconductivity. Here we show that a similar type of charge order is present in La5/3Sr1/3CoO4, an insulating analogue of the copper oxide superconductors containing cobalt in place of copper. The stripe phase we have detected is accompanied by short-range, quasi-one-dimensional, antiferromagnetic order, and provides a natural explanation for the distinctive hourglass shape of the magnetic spectrum previously observed in neutron-scattering measurements of La2-xSrxCoO4 and many hole-doped copper oxide superconductors. The results establish a solid empirical basis for theories of the hourglass spectrum built on short-range, quasi-static, stripe correlations.
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Babkevich
authors.affiliation: Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy, University of Central Lancashire, Preston, Lancashire PR1 2HE, UK.
authors.forename: P G
authors.initials: PG
authors.lastname: Freeman
authors.affiliation: Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Enderle
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Oxford OX1 3PU, UK.
authors.forename: D
authors.initials: D
authors.lastname: Prabhakaran
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Oxford OX1 3PU, UK.
authors.forename: A T
authors.initials: AT
authors.lastname: Boothroyd