Location of the superconducting hole condensate in Sr2YRu1-uCuuO6 by mu(+)SR

The magnetic and superconducting characteristics of sintered Sr2YRu1-uCuuO6 (for u = 0.05, 0.10, 0.15) were probed using transverse- and zero-field mu on-spin rotation (mu(+)SR). Since positive muons are attracted to oxygen io ns in the high-T-C oxides, Sr2YRu1-uCuuO6 should (and does) present two typ es of mu(+) sites, one in the YRuO4 layers and the other in the SrO layers. The transverse- and zero-field mu SR spectra for all three stoichiometries exhibit magnetic ordering at and below T-N approximate to 30 K, with a sta tic local field of similar to 3 kG. This transition is marked by a dramatic increase in the mu(+) spin relaxation rate as the temperature decreases be low T-N, corresponding to an increased static disordering of the magnetic m oments. Above T-N no static fields are observed. Instead, the data exhibit a slow dynamic depolarization, presumably due to rapid fluctuation of magne tic moments. Both transverse- and zero-field data also indicate a smaller s econd component (similar to 10%) that we associate with the SrO layer, exhi biting superconducting behavior in transverse field with an observed bulk T -C approximate to T-N similar to 30 K. (C) 2000 Elsevier Science B.V. All r ights reserved.