High-temperature superconducting diode effect in artificial Josephson junction of Bi₂Sr₂CaCu₂O₈₊_δ

An exciting new development in the field of superconducting electronics is the unearthing of the superconducting diode effect (SDE) manifested due to various mechanisms. The effect is the superconducting analogue of the semiconducting p-n junction diode where a system behaves superconducting for one direction of current flow and dissipative for the other direction. The effect is tunable with a magnetic field in some specific systems. SDEs demonstrated so far, however, require very low temperatures for operation (~ 4 K or less), which impedes their use in technological applications. We demonstrate SDE in an artificial Josephson junction of twisted Bi₂Sr₂CaCu₂O_8+δ (BSCCO), a high-T_c van der Waals material. This system shows a diode effect even above 77 K and is independent of the twist angle. As a figure of merit, we also observe the highest asymmetry (60 %) between switching currents for positive and negative bias at 20 K. A very small magnetic field applied perpendicular to the junction plane tunes the diode effect. Interestingly, we observe the SDE originates from the artificial Josephson junction at the interface, which breaks inversion symmetry, and not from the intrinsic Josephson junctions of the bulk BSCCO crystal.