Observation of superconducting diode effect

Area of Science:

• Condensed matter physics
• Quantum electronics
• Materials science

Background:

• Nonlinear optical and electrical effects arise from broken spatial inversion symmetry, enabling direction-selective particle transport.
• Semiconductor diodes exhibit nonreciprocal resistance but suffer from energy loss due to finite resistance.

Purpose of the Study:

• To realize a superconducting diode with unidirectional zero resistance, overcoming energy loss limitations of conventional diodes.
• To demonstrate a magnetically controllable superconducting diode in an artificial superlattice structure.

Main Methods:

• Fabrication of an artificial superlattice [Nb/V/Ta]_n lacking a center of inversion.
• Direct-current measurements to observe the resistance versus current behavior at the superconducting-to-normal transition.

Main Results:

• Observation of a nonreciprocal resistance curve, indicating diode behavior in the superconducting state.
• Demonstration of unidirectional zero resistance in the [Nb/V/Ta]_n superlattice due to nonreciprocal critical current.
• Attribution of the effect to magnetochiral anisotropy from broken spatial-inversion and time-reversal symmetries.

Conclusions:

• The developed superconducting diode enables phase-coherent and direction-selective charge transport.
• This breakthrough paves the way for constructing non-dissipative electronic circuits.
• The study highlights the potential of engineered superlattices for novel electronic functionalities.