RESONANT IONIC BONDING AND HIGH-TC SUPERCONDUCTIVITY

The implications of an electronic coupling model in high T(c) supercon ductors of YBCO are discussed in which the pairing mechanism is based upon the ionic bonding. Specifically, the bonding reaction Cu + O reve rsible Cu++ + O-- resonates at a frequency of I/2piHBAR in the CuO pla nes, where I = 0.4 eV is the ionic bonding energy. We formulate an Ham iltonian which allows for the reduction of the total energy by I each time two holes or two electrons form a pair. The total energy consists of kinetic energy calculable from band theory, and the ionic bonding energy proportional to I. We calculate (i) the effective Ginzburg-Land au free energy for all T < T(c), (ii) the energy gap, (iii) the anisot ropic London penetration depths, and (iv) the anisotropic coherence le ngths. General agreement is found between our calculations and experim ental data.