Presentation Momentum-resolved charge fluctuations proximate to the charge-order phase measured by resonant inelastic x-ray scattering

石井, 賢司  ,  吉田, 雅洋  ,  中, 惇  ,  石原, 純夫  ,  Jarrige, Ignace  ,  池内, 和彦  ,  村上, 洋一  ,  工藤, 一貴  ,  小池, 洋二  ,  永田, 知子  ,  深田, 幸正  ,  池田, 直  ,  水木純一郎

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. Spin fluctuations in the energy-momentum space have been studied widely using inelastic neutron scattering, and resonant inelastic x-ray scattering (RIXS) at the transition metal L-edge has become a complementary technique in measuring spin-flip magnetic excitations recently. In contrast, other degrees of freedom, i.e., charge and orbital, have hardly been explored so far.We applied the K-edge RIXS technique to two systems that show a charge order and observed the momentum-resolved charge fluctuations proximate to the charge-ordered phase in strongly correlated transition metal oxides. In the two-leg ladder of Sr14-xCaxCu24O41, charge fluctuations are enhanced at the propagation vector of the charge order (qCO) when the order is melted by raising the 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 high energy (~ 1 eV), suggesting that Coulomb repulsion between electrons is the principal interaction of the charge order.
International Conference on Low-Energy Electrodynamics in Solids, 2016

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