Static magnetic order in Bi2Sr2YCu2Ox and spin freezing in Bi2SrYCaCu2Ox detected by muon-spin rotation

Muon-spin rotation measurements have been performed on insulating samples of Y-doped Bi2Sr2CaCu2Ox. In Bi2Sr2YCu2Ox muon-spin precession frequencies have been observed in zero applied field which are attributed to antiferromagnetic ordering, probably in the CuO2 planes. The transition is broad with an ordering temperature of about 210 K. Bi2SrYCaCu2Ox appears to be a disordered magnetic system with a spin-freezing temperature of 15 K. These results establish that there are strong magnetic correlations in the Bi 2:2:1:2 phase which are analogous to those observed previously in La2-xSrxCuO4 and YBa2Cu3Ox.