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【Abstract】

A supercurrent diode exhibits different critical current magnitudes for opposite current directions. This effect is closely tied to the symmetry of the superconducting state, and serves as a new probe for unconventional superconductivity. For iron chalcogenides superconductors, we observed a field-free supercurrent diode effect in a van der Waals (vdW) Josephson junction (JJ) composed of Fe(Te,Se), providing clear evidence of time-reversal symmetry breaking. This finding establishes the essential symmetry requirement for Majorana bound states to emerge at zero field in Fe(Te,Se) from a new perspective. In FeSe/FeSe vdW JJ, we further observed a 0-pi juxtaposed Fraunhofer interference pattern alongside a field-free supercurrent diode effect with a symmetric field dependence. This observation challenges the expected antisymmetric field dependence from magnetic fields, suggesting an even stronger time-reversal symmetry breaking in FeSe. Beyond revealing fundamental symmetry properties, supercurrent rectification offers practical applications in cryogenic electronics, akin to semiconductor diodes. By integrating multiferroic NiI2 into a vdW JJ, we strategically designed the symmetry of the JJ to augment the diode’s field resilience. This design enables the supercurrent diode to withstand stray fields up to industrial standards for the first time. These advancements in supercurrent diode research and vdW JJs hold significant implications for quantum computing.