Interferometric Evidence of Nonvolatile Anomalous Phase Shifts in Exchange-Spin-Split Josephson Supercurrent Diodes

초록

The recent realization of zero-field, polarity-reversible supercurrent rectification in proximity-magnetized Rashba-type Pt Josephson junctions (JJs) enables the development of superconducting logic circuits and cryogenic memory applications. Here, we demonstrate a nonvolatile anomalous phase shift φ0 directly probed via superconducting quantum interferometry, providing phase-sensitive evidence of spontaneous time-reversal symmetry breaking in these Rashba-type systems. By replacing the Pt barrier with 5d or 4d element layers exhibiting different (para)magnetic susceptibilities, spin–orbit coupling properties, and electronic band structures, we elucidate the role of proximity effects in governing zero-field diode behavior. Ta (W) JJs exhibit zero-field diode efficiencies of ∼17% (∼5%) at 2 K, which are slightly (significantly) lower than those of Pt JJs. Notably, the diode polarity in Ta and W JJs is reversed relative to that in Pt JJs. Combined with the large zero-field diode efficiency (∼15% at 2 K) observed in highly magnetic-susceptible Pd JJs, these results show that nonvolatile φ0 and, consequently, zero-field diode performance can be tuned through proximity engineering of interfacial magnetic ordering and Rashba spin–orbit interaction.

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