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Anisotropic damping and wave vector dependent susceptibility of the spin fluctuations in La 2 − x Sr x CuO 4 studied by resonant inelastic x-ray scattering

DOI: 10.1103/PhysRevB.100.214510 DOI Help

Authors: H. C. Robarts (University of Bristol; Diamond Light Source) , M. Barthelemy (University of Bristol) , K. Kummer (European Synchrotron Radiation Facility (ESRF)) , Mirian Garcia-fernandez (Diamond Light Source) , J. Li (Diamond Light Source) , A. Nag (Diamond Light Source) , A. C. Walters (Diamond Light Source) , K. Zhou (Diamond Light Source; Swiss Light Source) , S. M. Hayden (University of Bristol)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 100

State: Published (Approved)
Published: December 2019
Diamond Proposal Number(s): 18469 , 18512

Abstract: We report high-resolution resonant inelastic x-ray scattering (RIXS) measurements of the collective spin fluctuations in three compositions of the superconducting cuprate system La 2 − x Sr x CuO 4 . We have mapped out the excitations throughout much of the two-dimensional ( h , k ) Brillouin zone. The spin fluctuations in La 2 − x Sr x CuO 4 are found to be fairly well described by a damped harmonic oscillator model, thus our data allows us to determine the full wave vector dependence of the damping parameter. This parameter increases with doping and is largest along the ( h , h ) line, where it is peaked near ( 0.2 , 0.2 ) . We have used a new procedure to determine the absolute wave vector dependent susceptibility for the doped compositions La 2 − x Sr x CuO 4 ( x = 0.12 , 0.16 ) by normalizing our data to La 2 CuO 4 measurements made with inelastic neutron scattering (INS). We find that the evolution with doping of the intensity of high-energy excitations measured by RIXS and INS is consistent. For the doped compositions, the wave vector dependent susceptibility is much larger at ( 1 4 , 1 4 ) than at ( 1 2 , 0 ) . It increases rapidly along the ( h , h ) line towards the antiferromagnetic wave vector of the parent compound ( 1 2 , 1 2 ) . Thus, the strongest magnetic excitations, and those predicted to favor superconductive pairing, occur towards the ( 1 2 , 1 2 ) position as observed by INS.

Journal Keywords: Spin dynamics; Superconductivity; High-temperature superconductors; Resonant inelastic x-ray scattering

Subject Areas: Materials, Physics

Instruments: I21-Resonant Inelastic X-ray Scattering (RIXS)

Other Facilities: European Synchrotron Radiation Facility Beamline ID32