Doping-induced enhancement of the switch rate of tilted O octahedra tunneling within multiwell potentials in La2-xSrxCuO4

Recent anelastic relaxation experiments demonstrated that the O octahedra in La2CuCO4 can switch between the minima of a multiwell potential both in a slow collective fashion and locally with a tunneling driven dynamics. New results are presented for low Sr doping (x <= 0.03) on the absorption peak due to the local tilt motion.This peak is drastically shifted to lower temperature with increasing x, demonstrating that doping enhances the local tilt rate ?-1. These observations can be qualitatively explained supposing that a considerable fraction of the octahedra are able to tunnel between different tilt orientations forming tunneling systems (TS). The large enhancement of the rate even at small doping demonstrates that the transitions of the TS between their eigenstates occur with a rate ?-1 governed by the interaction with the excitations of the doped holes.