Muon Spin Relaxation Studies of Zn-Substitution Effects in High- Tc Cuprate Superconductors

We have performed transverse-field muon spin relaxation measurements of the Zn-substituted cuprate high- Tc superconductors: La2-xSrx(Cu1-yZny)O4 and YBa2(Cu1-yZny)3O6.63. The superconducting carrier density/effective mass ns/m* ratio at T→0 decreases with increasing Zn concentration, in a manner consistent with our “swiss cheese” model in which charge carriers within an area πξab2 around each Zn are excluded from the superfluid. We discuss this result in the context of Bose condensation, pair localization, and pair breaking.