Fig. 1. Scanning Kerr microscopy.

a Overview of ac MOKE microscopy setup. The sample is surrounded by a coil that generates an out-of-plane ac magnetic field. b Unmodulated Kerr ellipticity map taken at T = 120 K reveals stripe-like magnetic domains. c–j ac MOKE maps measured at temperatures ranging from 120 to 174 K. A 28 Oe ac magnetic field was applied at a frequency of 1 kHz. The normalized ac Kerr ellipticity amplitude ${\mathrm{\Phi }}_{\mathrm{AC}}/{\mathrm{\Phi }}_{\mathrm{DC}}$ is significantly reduced at 140 K.