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 spin rotation (mu(+) SR). In general, positive muons are attracted to oxygen ions in the high-T-c oxides, and so, Sr2YRu1-uCuuO6 should (and does) present two types of mu(+) sites, those associated with the oxygen in the YRuO4 layers and those associated with the SrO-layer oxygen. The tranverse- and zero-field data for all three stoichiometries u exhibit a sudden onset of magnetic structure at T-N similar to 30 K, With a static local field of similar to 3 kG. This transition is marked by a dramatic increase in the relaxation rate as the temperature decreases below T-N, corresponding to an increased static disordering of the magnetic moments. Above T-N no static fields are observed. Instead the data exhibit a slow dynamic depolarization, presumably due to the rapid fluctuation of paramagnetic moments. Both transverse- and zero-field data also indicate a smaller second component (similar to 10%) which we associate with the SrO layer, exhibiting superconducting behavior in transverse field with an observed T-c approximate to T-N similar to 30 K.