Fig. 1: Observation of SAF skyrmions.
a Material stack for the SAF. Buff. denotes Ta(3)/Pt(2.5) (thicknesses in nanometres). b Out-of-plane hysteresis loop measured by vibrating sample magnetometry. mz denotes the reduced out-of-plane component of the magnetisation. c, d X-ray magnetic circular dichroism scanning transmission X-ray microscopy (XMCD-STXM) images acquired at c the Co L3 and d the Fe L3 absorption edges after out-of-plane demagnetisation. An isolated skyrmion is observed at the top of the image (Sk.2). e XMCD-STXM image acquired at the Co edge showing an isolated skyrmion (Sk.1). The image was recorded at zero field after the successive application of an external magnetic field (180 mT) out of and in the plane of the layers. f, g XMCD microcopy images obtained from amplitudes of ptychography reconstructions of the skyrmion in the black box in e acquired at the Co and Fe edges, respectively. h Normalised XMCD signal obtained from line-scans along the diameter of skyrmions Sk.1 and Sk.2, in c, d, f, g, respectively. The signal for Co is inverted for comparison purposes and the solid lines are Gaussian fits. i Distribution of skyrmion diameters extracted from various STXM images. Scale bar in c–e and in f, g is 1 μm and 500 nm, respectively.
