Reversible field-free superconducting diode effect controlled by an antiferromagnet

Abstract: The semiconductor diode, which allows current to flow preferentially in one direction, is a fundamental building block of numerous modern electronic circuits. Its superconducting analogue---the superconducting diode effect---enables directional dissipationless current flow and may provide similar functionality in future superconducting quantum circuits. Realization of such a nonreciprocal supercurrent requires broken time-reversal symmetry. At zero applied field, this has been typically associated either with intrinsic unconventional superconductivity or extrinsic spin-split electronic states induced by magnetic proximity. Here we demonstrate a field-free superconducting diode effect in conventional superconducting Al proximitized by collinear antiferromagnetic CuMnAs, whose electronic structure breaks time-reversal symmetry without generating spin splitting. By tuning the proximity effect through an insulating AlAs interlayer and correlating the reversal of the diode polarity with the reversal of the remanent Néel state, we establish that the antiferromagnet controls the superconducting diode effect. Our results show that neither spin-split bands nor net magnetization is required for a magnetically controlled field-free superconducting diode effect, extending superconducting nonreciprocity to a broader class of collinear compensated magnets.