Open AccessEvidence for strong electron-lattice coupling in La{sub 2{minus}x}Sr{sub x}NiO{sub 4}
Author(s) -
R. J. McQueeney,
J. L. Sarrao
Publication year - 1999
Language(s) - English
Resource type - Reports
DOI - 10.2172/334199
Subject(s) - non blocking i/o , cuprate , condensed matter physics , inelastic neutron scattering , crystallite , lattice (music) , phonon , doping , spectral line , neutron diffraction , crystal structure , inelastic scattering , scattering , materials science , physics , crystallography , chemistry , biochemistry , acoustics , optics , catalysis , astronomy
The inelastic neutron scattering spectra were measured for several Sr concentrations of polycrystalline La{sub 2{minus}x}Sr{sub x}NiO{sub 4}. The authors find that the generalized phonon density-of-states is identical for x = 0 and x = 1/8. For x = 1/3 and x = 1/2, the band of phonons corresponding to the in-plane oxygen vibrations (> 65 meV) splits into two subbands centered at 75 meV and 85 meV. The lower frequency band increases in amplitude for the x = 1/2 sample, indicating that it is directly related to the hole concentration. These changes are associated with the coupling of oxygen vibrations to doped holes which reside in the NiO{sub 2} planes and are a signature of strong electron-lattice coupling. Comparison of La{sub 1.9}Sr{sub 0.1}CuO{sub 4} and La{sub 1.875}Sr{sub 0.125}NiO{sub 4} demonstrates that much stronger electron-lattice coupling occurs for particular modes in the cuprate for modest doping and is likely related to the metallic nature of the cuprate