1202.4994 (C. J. Bonnoit et al.)

Probing electronic order via coupling to low energy phonons in
superconducting Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+δ}$    [PDF]

C. J. Bonnoit, D. R. Gardner, R. Chisnell, A. H. Said, Y. Okada, T. Kondo, T. Takeuchi, H. Ikuta, D. E. Moncton, Y. S. Lee

We report high-resolution inelastic x-ray scattering measurements of the
acoustic phonons in the single-layer cuprate
$Bi_{2}Sr_{2-x)La_{x}CuO_{6+\delta}$. These measurements reveal anomalous
broadening of the longitudinal acoustic phonon near the (1/4,1/4,0) wavevector.
The observed wavevector and its doping dependence indicate the coupling of the
phonons to an underlying electronic density wave state. In addition, a
comparison of the scattered intensities for x-ray energy-gain and x-ray
energy-loss indicates that both time-reversal and inversion symmetries are
broken in the material. Upon cooling, the effects of symmetry breaking are
enhanced in the pseudogap state.

View original: http://arxiv.org/abs/1202.4994