Giant Electron-Phonon Anomaly in Doped and Other Cuprates
Figure 11
Temperature dependence of the bond-stretching phonons at select wavevectors. Energy scans taken on La1.875Ba0.125CuO4 (a, b) and on La1.85 Sr0.15 CuO4 (c, d, e) at 10 K (a, c) and 330 K (b, d) [37]. The phonon at is “normal” in that it has a Gaussian lineshape on top of a linear background. This background results from multiphonon and incoherent scattering and has no strong dependence on Q. The intensity reduction of this phonon in La1.875Ba0.125CuO4 from 10 K (a) to 330 K (b) is consistent with the Debye-Waller factor. At , there is extra intensity on top of the background in the tail of the main peak. It originates from one-phonon scattering that extends to the lowest investigated energies, while the peak intensity is greatly suppressed as discussed in the text. The effect is reduced but does not disappear at 330 K. Note that 330 K in (b) is shown instead of 300 K in the same plot in [37] because of a typographical error in the latter. Integrated intensity of the phonon decreases from to due to the decrease of the structure factor.
