A diode is an element that has the characteristic that a current flows well in the forward direction but hardly flows in the reverse direction.Among them, semiconductor diodes are used in many electronic components such as rectifiers, mixers, and photodetectors.

　However, since the electrical resistance of semiconductors is not zero, energy loss in each component becomes a problem.Therefore, it has been desired to impart the characteristics of a diode to a superconductor having zero electrical resistance instead of a semiconductor, that is, to realize a superconducting diode having zero resistance only in a specific direction.

　In this study, in a superconducting artificial lattice having an asymmetric structure consisting of a niobium (Nb) layer, a vanadium (V) layer, and a tantalum (Ta) layer, superconducting-normal conduction switching is possible depending on the direction of the external magnetic field and current. discovered.This means that the Nb / V / Ta artificial lattice functions as a superconducting diode, which is the first demonstration of the superconducting diode effect.

　When there is a spatial inversion symmetry breaking in the material, the non-linear response of the current causes non-reciprocal charge transport.This non-reciprocal charge transport phenomenon has been applied to various components constituting electronic circuits as diode elements, but there have been few reports on superconducting materials so far. The Nb / V / Ta artificial lattice is considered to have non-reciprocity because the spatial inversion symmetry is broken in the thin film stacking direction.

　The superconducting diode effect observed in this study is expected to contribute significantly to the establishment of energy-dissipating and direction-controllable charge transport technology, and it is expected that electronic circuits with extremely small energy loss will be realized in the future.

Paper information:[Nature] Observation of superconducting diode effect