EFFECT OF ZN DOPING ON CHARGE-TRANSPORT IN YBA2CU3O7+GAMMA

The resistivity and the in-plane Hall coefficient are investigated on Zn-doped YBa2Cu3O7-y single crystals with emphasis on the underdoped spin-gap phase (y similar to 0.37) where a correlation between charge transport and spin dynamics is clearly seen. The doped Zn acts as a strong potential scatterer on one hand, and induces a local spin magnetic moment on the other even when the charge carriers are not localized. It is found that the characteristic temperature in these transport coefficients, which indicates that a spin gap starts to open, do not change with Zn doping in contrast to a radical depression of the superconducting transition temperature.