Spatial Magnetic Phase Separation in the Oxygen Deficient Perovskite SrCoO$_{3-y}$*

We report here the unique local structure of the magnetically phase separated perovskite SrCoO$_{3-y}$ by means of transverse field (TF) and zero field (ZF) muon spin rotation. Previously we reported samples of SrCoO$_{3}$ and SrCoO$_{2.875}$ have unique magnetic and crystallographic phases, whereas samples of intermediate composition have multiple magnetic transitions but a single structural phase (\textit{Appl. Phys. Lett}. \textbf{99}, 052503 (2011)). Muon measurements establish that the intermediate compounds show spatially separated, distinct magnetic phases -- true magnetic phase separation. In addition, the two magnetic phases evolve with temperature in an unusual way indicating that the two phases remain coupled.