Muon spin rotation in Sr2YRU1-uCUuO6

The magnetic and superconducting behaviors of sintered Sr2YRu1-uCuuO6 (for u = 0.05, 0.10, 0.15) were probed using transverse- and zero-field muon spi n rotation (mu(+) SR). In general, positive muons are attracted to oxygen i ons in the high-T-c oxides, and so, Sr2YRu1-uCuuO6 should (and does) presen t two types of mu(+) sites, those associated with the oxygen in the YRuO4 l ayers and those associated with the SrO-layer oxygen. The tranverse- and ze ro-field data for all three stoichiometries u exhibit a sudden onset of mag netic structure at T-N similar to 30 K, With a static local field of simila r to 3 kG. This transition is marked by a dramatic increase in the relaxati on rate as the temperature decreases below T-N, corresponding to an increas ed static disordering of the magnetic moments. Above T-N no static fields a re observed. Instead the data exhibit a slow dynamic depolarization, presum ably due to the rapid fluctuation of paramagnetic moments. Both transverse- and zero-field data also indicate a smaller second component (similar to 1 0%) which we associate with the SrO layer, exhibiting superconducting behav ior in transverse field with an observed T-c approximate to T-N similar to 30 K.