Fig. 1: Magnetic response of the EuS/Nb bilayer to an ac current \({I}_{x}^{ac}\).
a Schematic diagram of the measurement setup, showing a EuS/Nb Hall bar structure, along with the scanning SQUID-on-tip (SOT) probe. b SOT image of the ac out-of-plane (OOP) component of the magnetic field \({B}_{z}^{ac}(x,\, y)\) modulated with respect to an oscillating transport current with root-mean-square (RMS) value \({I}_{x}^{ac}\simeq 0.15\)mA < Ic. Blue (red) corresponds to a positive (negative) OOP component of the field emanating from the Nb strip. The device was zero-field cooled to 4.2 K, below the superconducting transition (Tc ~ 5.5 K) and Curie temperature (TC ~ 20 K). c Same as (b) but with RMS value \({I}_{x}^{ac}\simeq 0.42\)mA > Ic. In this case, the polarity of the signal depends on whether the magnetic feature appears in phase (blue) or at a π-phase (red) with respect to the oscillating current. The value of the measured magnetic field can be obtained from the color bar on the right side of the images. d R(T) measurements of the device showing the superconducting transition.
