Browsing by Author "Lamago, D"
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- ItemHighly anisotropic anomaly in the dispersion of the copper-oxygen bond-bending phonon in superconducting YBa2Cu3O7 from inelastic neutron scattering(American Physical Society, 2011-10-19) Raichle, M; Reznik, D; Lamago, D; Heid, R; Li, Y; Bakr, M; Ulrich, C; Hinkov, V; Hradil, K; Lin, CT; Keimer, BMotivated by predictions of a substantial contribution of the "buckling'' vibration of the CuO2 layers to d-wave superconductivity in the cuprates, we have performed an inelastic neutron scattering study of this phonon in an array of untwinned crystals of YBa2Cu3O7. The data reveal a pronounced softening of the phonon at the in-plane wave vector q = (0, 0.3) upon cooling below similar to 105 K, but no corresponding anomaly at q = (0.3,0). Based on the observed in-plane anisotropy, we argue that the electron-phonon interaction responsible for this anomaly supports an electronic instability associated with a uniaxial charge-density modulation and does not mediate d-wave superconductivity. © 2011, American Physical Society.
- ItemSpin-gap evolution upon Ca doping in the spin-ladder series Sr(14−x)CaxCu24O41 studied by inelastic neutron scattering(Americal Physical Society, 2013-07-03) Deng, G; Tsyrulin, N; Bourges, P; Lamago, D; Rønnow, HM; Kenzelmann, M; Danilkin, SA; Pomjakushina, E; Conder, KThe spin-gap evolution upon Ca doping in Sr14-xCaxCu24O41 was systematically investigated using inelastic neutron scattering. We discover that the singlet-triplet spin-gap excitation survives in this series with x up to 13, indicating the singlet dimer ground state in these compounds. This observation corrects the previous speculation that the spin gap collapses at x similar to 13 by the NMR technique. The strong intensity modulation along Q(H) in x = 0 gradually evolves into a Q-independent feature in x > 11. This could be attributed to the localized Cu moment magnetism developing into an itinerant magnetism with increasing x. It is a surprise that the spin gap persists in the normal state of this spin-ladder system with metallic behavior, which evidences the possibility of magnetically mediated carrier pairing mechanism in a two-leg spin-ladder lattice. © 2013, American Physical Society.