Mu-Sr In Oxygen Deficient Yba2cu3ox(6.5-Less-Than-Or-Equal-To-X-Less-Than-Or-Equal-To-7.0)

A systematic mu-SR study of the local magnetic field distribution in a series of oxygen deficient YBa2Cu3O(x) samples with 6.5 less-than-or-equal-to x less-than-or-equal-to 7.0 is reported. Special attention was given to perform the experiments under the same conditions, so that the oxygen content of the measured samples was the only parameter varied. The behavior of the depolarization rate sigma as a function of the oxygen content x was found to have strong similarities with the behavior of the critical temperature T(c) as a function of x. In particular, two step-like increases of sigma were observed above x = 6.7 and 6.9. The temperature dependence of the normalized depolarization rate sigma(T)/sigma(0) is well described by the two-fluid model for x greater-than-or-equal-to 6.781(1) and clearly deviates from this behavior for x less-than-or-equal-to 6.704(1). Our results are compared to those obtained by other groups.