Novel insulator to metal transition and superconductivity in Sr-doped La2CuO4

We have studied the charge dynamics, of Sr-doped La2CuO4 at hole concentration p = 0.07. We observed a clear indication of the competition between two new characteristic collective modes of the Wigner lattice orders suggested earlier: one corresponds to a T-c = 15 K superconductivity and the other to T, = 30 K. Our results naturally explain the recent observation of metallic transport in extremely low (1%) Sr-doped La2CuO4 and establish a novel insulator to metal transition mechanism and superconductivity in the two-dimensional Wigner lattice ground state.-Ne suggest that the fluctuations of the relative phase between the superconducting condensate and the Wigner lattice order can provide an answer to the unidentifted mode in the c-axis conductivity that appears only below T-c.