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)

Abstract

The superconductivity depression mechanisms at x≈1/8 in La2−xBaxCuO4 and Zn substitution in La2−xSrxCuO4 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 B3u 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.