A model which couples the normal state electrons to the two level systems provided by the apex oxygen atoms in high Tc superconductors is presented. A path integral approach is used to describe the quantum tunneling between the minima of the double well potential. The model is applied to evaluate the out of plane electrical resistivity \rho_c in the YBCO compound. At small values of the tunneling energy the electrons follow the double well potential quasiadiabatically and the short range Coulomb correlations lead to a negative slope d\rho_c /dT up to about 150K. The obtained numerical values of \rho_c are in good agreement with experimental analysis. By increasing the tunneling energy the adiabatic approximation breaks down and the two level system scattering mechanism produces a T^2 contribution to \rho_c.
Anharmonic Effects on the out-of-plane Electrical Resistivity ρc in YBCO Superconductors
ZOLI, Marco
1995-01-01
Abstract
A model which couples the normal state electrons to the two level systems provided by the apex oxygen atoms in high Tc superconductors is presented. A path integral approach is used to describe the quantum tunneling between the minima of the double well potential. The model is applied to evaluate the out of plane electrical resistivity \rho_c in the YBCO compound. At small values of the tunneling energy the electrons follow the double well potential quasiadiabatically and the short range Coulomb correlations lead to a negative slope d\rho_c /dT up to about 150K. The obtained numerical values of \rho_c are in good agreement with experimental analysis. By increasing the tunneling energy the adiabatic approximation breaks down and the two level system scattering mechanism produces a T^2 contribution to \rho_c.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
