title: Observation of momentum-resolved charge fluctuations proximate to the charge-order phase using resonant inelastic x-ray scattering.
abstract: In strongly correlated electron systems, enhanced fluctuations in the proximity of the ordered states of electronic degrees of freedom often induce anomalous electronic properties such as unconventional superconductivity. While spin fluctuations in the energy-momentum space have been studied widely using inelastic neutron scattering, other degrees of freedom, i.e., charge and orbital, have hardly been explored thus far. Here, we use resonant inelastic x-ray scattering to observe charge fluctuations proximate to the charge-order phase in transition metal oxides. In the two-leg ladder of Sr(14-x)Ca(x)Cu24O41, charge fluctuations are enhanced at the propagation vector of the charge order (qCO) when the order is melted by raising temperature or by doping holes. In contrast, charge fluctuations are observed not only at qCO but also at other momenta in a geometrically frustrated triangular bilayer lattice of LuFe2O4. The observed charge fluctuations have a high energy (~1 eV), suggesting that the Coulomb repulsion between electrons plays an important role in the formation of the charge order.
authors.affiliation: SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan.|Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ishii
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Naka
authors.affiliation: Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.|CREST, JST, Chiyoda, Tokyo 102-0076, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ishihara
authors.affiliation: SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Jarrige
authors.affiliation: SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan.|Research Center for Neutron Science and Technology, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ikeuchi
authors.affiliation: Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Murakami
authors.affiliation: Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kudo
authors.affiliation: Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Koike
authors.affiliation: Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nagata
authors.affiliation: Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Fukada
authors.affiliation: Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ikeda
authors.affiliation: SPring-8, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148, Japan.|School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Mizuki