Independent Control of Low-Energy Resonant States and Polaron States by the Zn-Doping and the Structural Transition in La2?x Sr x CuO4 and La2?x Ba x CuO4 (x=0.11)

摘要

The superconductivity depression mechanisms at x≈1/8 in La2?x Ba x CuO4 and Zn substitution in La2?x Sr x CuO4 were investigated by Raman scattering. About 80% of low-energy electronic states are two-dimensional at x≈1/8 and form the Fermi arc around (π/2,π/2). The low-energy states are composed of the resonant peak relating to the insulator–metal transition and the polaron states of the B 3u phonons. Zn substitution depresses the resonant peak, while the LTT structure depresses the polaron states. The superconductivity is suppressed if one of them is reduced.