Magnetic Penetration Depth And Condensate Density Of Cuprate High-T-C Superconductors Determined By Muon-Spin-Rotation Experiments

We summarize our results of transverse-field muon-spin-relaxation (TF-mu SR) experiments on a variety of polycrystalline cuprate high-T(c) superconducting systems. In this paper we present the conditions under which the mu SR depolarization rate at low temperatures sigma(0) proportional to lambda(ab)(-2)(0) proportional to n(s)(0)/m(ab)* is determined in a unique way by the doping state of CuO(2) planes and the consequent critical temperature T(c). Disorder and pinning effects due to various sorts and amounts of dopant atoms do not affect sigma(0). From our results on YBa(2)CU(3)O(77-delta), YBa(2)Cu(4)O(8), and Y(2)Ba(4)CU(7)O(15-delta) (systems having both planes and chains) we conclude that a superconducting condensate is not only formed in the CuO(2) planes but is induced additionally in the CuO chains. This chain condensate is rapidly suppressed by any disorder in the chains and depends strongly on the oxygen ordering.