Measurements of the spin rotation and depolarization of implanted positive muons have revealed that La2SrCu2O6+δ, La2CaCu2O6+δ, and La1.9Y0.1CaCu2O6+δ, members of the double-layer perovskite family La2MCu2O6+δ (M=Ca,Sr), display magnetic ordering similar to that of La2−xSrxCuO4−y and YBa2Cu3Ox Their magnetic order parameters are remarkably close to those of the other layered cuprates. A superconducting minority phase has been detected in La2CaCu2O6+δ (δ≥0.02), with onset at ∼45 K and accompanied by a change in the muon-spin-precession signals from the majority antiferromagnetic phase, phenomena absent in La2SrCu2O6+δ. This behavior was attributed to mobility and local clustering of intercalated oxygen excess in the layer between the CuO2 planes.

This work was supported by NSERC (Canada), DOE Grant No. DE-FG05-88ER45353, the CICYT and the MIDAS project (Spain), and the CEE.

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.

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