Observation of magnetic vortex pairs at room temperature in a planar α-Fe2O3/Co heterostructure by Chmiel, FP, Price, NW, Johnson, RD, Lamirand, A, Schad, J, Laan, GVD, Harris, DT, Irwin, J, Rzchowski, MS, Eom, C-B, Radaelli, PG