title: Evidence for short-range-ordered charge stripes far above the charge-ordering transition in La1.67Sr0.33NiO4.
abstract: The temperature evolution of structural effects associated with charge order (CO) and spin order in La1.67Sr0.33NiO4 has been investigated using neutron powder diffraction. We report an anomalous shrinking of the c/a lattice parameter ratio that correlates with T(CO). The sign of this change can be explained by the change in interlayer Coulomb energy between the static-stripe-ordered state and the fluctuating-stripe-ordered state or the charge-disordered state. In addition, we identify a contribution to the mean-square displacements of Ni and in-plane O atoms whose width correlates quite well with the size of the pseudogap extracted from the reported optical conductivity, with a non-Debye-like component that persists below and well above T(CO). We infer that dynamic charge-stripe correlations survive to T∼2T(CO).
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: A M Milinda
authors.initials: AM
authors.lastname: Abeykoon
authors.forename: Emil S
authors.initials: ES
authors.lastname: Božin
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Yin
authors.forename: Genda
authors.initials: G
authors.lastname: Gu
authors.forename: John P
authors.initials: JP
authors.lastname: Hill
authors.forename: John M
authors.initials: JM
authors.lastname: Tranquada
authors.forename: Simon J L
authors.initials: SJ
authors.lastname: Billinge