Magnetic frustration model and superconductivity in doped planar CuO₂ systems

We present a model for the magnetic phases and superconductivity in doped planar CuO₂ systems. Electronic holes on the oxygen ions introduce local ferromagnetic exchange couplings between the Cu spins. The resulting frustration destroys the antiferromagnetic state characterizing the undoped planes, and generates a new spin-glass phase. This frustration also yields an attractive interaction between the holes, whose range decreases with increasing doping. We use the BCS approximation to obtain an estimate of the superconducting transition temperature T_c(x) for La_2-xSr_xCuO₄.