Scalable superconducting diodes achieve record operation at 86 K

Background and challenges

Superconducting diodes, which allow electrical current to flow preferentially in one direction without energy dissipation, are key components for next-generation low-power electronics and for exploring time-reversal symmetry in quantum systems. However, achieving both high operating temperatures and scalable device integration has remained a long-standing challenge. While the superconducting diode effect has been demonstrated in various platforms, including superlattices, two-dimensional materials, and microbridges, most implementations rely on low-transition-temperature superconductors, limiting their practical applicability. Layered cuprate superconductors naturally host intrinsic Josephson junctions formed by atomic-scale barriers, which have been widely used in terahertz sources and detectors. Recent studies have further demonstrated high-temperature superconducting diode effects in twisted Bi₂Sr₂CaCu₂O_8+δ (BSCCO) flakes, where artificial Josephson junctions exhibit twist-angle-dependent nonreciprocity, highlighting the potential of cuprate systems. However, these approaches still face challenges in device uniformity and scalable fabrication. In contrast, intrinsic Josephson junctions offer atomic-scale thickness and inherent scalability, yet their potential for nonreciprocal superconducting transport remains largely unexplored, particularly in achieving both high performance and large-scale integration.

A scalable high-temperature platform

Recently, a research team led by Prof. Huabing Wang at Nanjing University developed a scalable platform for high-temperature superconducting diodes based on intrinsic Josephson junctions in BSCCO. By introducing a wedge-shaped geometry to break spatial inversion symmetry and applying magnetic field control, the team realized a robust superconducting diode effect operating up to 86 K, setting a new record for this class of devices. The diode efficiency can be continuously tuned by adjusting the number of stacked junctions, offering a flexible route for device optimization.

Microscopic mechanism and performance optimization

To understand the underlying mechanism, the researchers established a microscopic model based on the Lawrence-Doniach framework, capturing the coupled dynamics of interlayer and intralayer supercurrents. The study reveals that the wedge geometry induces spatially nonuniform current distributions, leading to a strongly anharmonic current-phase relation. This anharmonicity, significantly enhanced by the atomic-scale thickness of intrinsic junction barriers, plays a central role in generating the superconducting diode effect. Both theoretical analysis and experimental measurements show that the diode performance strongly depends on the number of junctions. As the number of stacked junctions decreases, the anharmonicity becomes more pronounced, resulting in enhanced nonreciprocity. In the single-junction limit, the device reaches optimal performance. By exploiting surface intrinsic Josephson junctions, the team fabricated single-junction devices with a diode efficiency of up to 40 percent, significantly outperforming multi-junction counterparts.

Zero-field memory and large-scale integration

Importantly, the researchers also observed a robust zero-field memory effect in these devices. This effect arises from trapped magnetic vortices within the material, which preserve time-reversal symmetry breaking even after the external magnetic field is removed. As a result, the diode polarity can be programmed and retained without continuous power input, enabling nonvolatile functionality. In addition, the team demonstrated excellent scalability by fabricating an array of 201 intrinsic Josephson diodes. The array exhibits highly consistent and reproducible behavior, highlighting the potential of this platform for large-scale integration. This work establishes intrinsic Josephson junctions as a promising route toward high-temperature, scalable, and programmable superconducting electronics, opening new opportunities for energy-efficient information technologies.

The study, titled “Scalable high-temperature superconducting diodes enabled by intrinsic Josephson junctions,” was published in National Science Review. The work was carried out through collaboration among Nanjing University, Purple Mountain Laboratories, and University of Antwerp. Co-corresponding authors include Dr. Yangyang Lyu, Prof. Yong-Lei Wang, and Prof. Huabing Wang (Research Institute of Superconductor Electronics, Nanjing University), and Prof. Da Wang (National Laboratory of Solid State Microstructures & School of Physics, Nanjing University).