Fig. 1: Experimental setup and diffraction images.

a Measurement geometry: a magnetic thin film sample is pumped by an optical infrared laser pulse and probed by a circularly polarized X-ray FEL pulse with an incident angle of Θ = 44° (wavevector k, s-polarization (σ) and p-polarization (π)) that scatters on the sample. Afterwards an IR-protected charge-coupled device (CCD) detector records the magnetic SAXS pattern. b MFM image of a typical labyrinth domain pattern of the [Ta(5.3 nm)/Co₂₀Fe₆₀B₂₀(0.93 nm)/Ta(0.08 nm)/MgO(2.0 nm)]_x20/Ta(1.6 nm) sample. The inset shows the FFT with the first order peak corresponding to isotropic distributed labyrinthine stripes with a domain periodicity of (455+/−30) nm. These magnetic structures lead to the SAXS signals for left-hand (CL) and right-hand (CR) circular polarized incident X-rays. d The resulting sum =  CL+CR (Eq. (1)) of the diffraction pattern confirms that the diffraction corresponds to the magnetic domains observed by MFM. e The dichroic scattering signal = CL-CR (Eq. (2)) and its azimuthal dependence f confirms the presence of c right-handed chiral Néel (cycloidal) domain walls.