Resonating–valence-bond theory of phase transitions and superconductivity inLa2CuO4-based compounds

We identify the mysterious high-T ‘‘twitch’’ transition in ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$ with the mean-field resonating-valence-bond transition of the Heisenberg model of Baskaran, Zou, and Anderson. The structure distortions are caused by Coulomb correlations of the pair wave function. In the pure compound the pseudo-Fermi surface of the spin soliton nests and antiferromagnetism occurs at 240 K. We discuss briefly superconductivity and the nature of excitations in the system.