Non-reciprocity of vortex-limited critical current in conventional superconducting micro-bridges

Non-reciprocity in the critical current has been observed in a variety of superconducting systems and has been called the superconducting diode effect. The origin underlying the effect depends on the symmetry breaking mechanisms at play. We investigate superconducting micro-bridges of NbN and also NbN/magnetic insulator (MI) hybrids. We observe a large diode efficiency of approximate to 30% when an out-of-plane magnetic field as small as 25 mT is applied. In both NbN and NbN/MI hybrid, we find that the diode effect vanishes when the magnetic field is parallel to the sample plane. Our observations are consistent with the critical current being determined by the vortex surface barrier. Unequal barriers on the two edges of the superconductor strip result in the diode effect. Furthermore, the rectification is observed up to 10 K, which makes the device potential for diode based applications over a larger temperature range than before.

Automated summary

Non-reciprocity in the critical current, known as the superconducting diode effect, has been observed in NbN micro-bridges and NbN/magnetic insulator hybrids. The origin of this effect is related to the symmetry breaking mechanisms. The diode effect disappears when the magnetic field is parallel to the sample plane. The rectification is observed at temperatures up to 10 K, expanding the potential applications of this device.