Friedel oscillations and charge-density wave pinning in quasi-one-dimensional conductors: An x-ray diffraction study

We present an x-ray diffraction study of the vanadium-doped blue bronze ${\mathrm{K}}_{0.3}\left({\mathrm{Mo}}_{0.972}{\mathrm{V}}_{0.028}\right){\mathrm{O}}_3.$ At low temperature, we have observed both an intensity asymmetry of the $\pm {2k}_F$ satellite reflections relative to the pure compound, and a profile asymmetry of each satellite reflections. We show that the profile asymmetry is due to Friedel oscillation around the V substituant and that the intensity asymmetry is related to the charge-density-wave (CDW) pinning. These two effects, intensity, and profile asymmetries, give access to the local properties of CDW in disordered systems, including the pinning and even the phase shift of Friedel oscillations.