Direct observation of a superconducting vortex diode

Magnetic response to an ac current

The device consists of a EuS/Nb bilayer patterned into a Hall bar (Fig. 1a; see Methods). We assume that there should be no effect on the magnetic properties of the EuS film due to the coupling with superconducting Nb. We verify this assumption by performing global magnetization measurements on an unpatterned EuS/Nb device with identical thicknesses, which show a negligible difference across the SC transition temperature (Supplementary Fig. S1). We apply an ac current \({I}_{x}^{ac}\) along the EuS/Nb wires and simultaneously record the magnetic field…