Time-reversal symmetry breaking superconductivity between twisted cuprate superconductors

• DOI: 10.1126/science.abl8371
• Publication Date: 2023-12-07T19:00:38Z
• Authors: S. Y. Frank Zhao; Xiaomeng Cui; Pavel A. Volkov; Hyobin Yoo; Sangmin Lee; Jules A. Gardener; Austin J. Akey; Rebecca Engelke; Yuval Ronen; Ruidan Zhong; Genda Gu; Stephan Plugge; Tarun Tummuru; Miyoung Kim; Marcel Franz; Jedediah H. Pixley; Nicola Poccia; Philip Kim
• Keywords: T-symmetry

Twisted interfaces between stacked van der Waals (vdW) cuprate crystals present a platform for engineering superconducting order parameters by adjusting stacking angles. Using cryogenic assembly technique, we construct twisted vdW Josephson junctions (JJs) at atomically sharp Bi2Sr2CaCu2O8+x crystals, with quality approaching the limit set intrinsic JJs. Near 45° twist angle, observe fractional Shapiro steps and Fraunhofer patterns, consistent existence of two degenerate ground states related time-reversal symmetry (TRS). By programming JJ current bias sequence, controllably break TRS to place into either states, realizing reversible diodes without external magnetic fields. Our results open path topological devices higher temperatures.