Time-reversal symmetry breaking superconductivity between twisted cuprate superconductors

• 成果类型: Article
• 署名作者: Zhao, S. Y. Frank; Cui, Xiaomeng; Volkov, Pavel A.; Yoo, Hyobin; Lee, Sangmin; Gardener, Jules A.; Akey, Austin J.; Engelke, Rebecca; Ronen, Yuval; Zhong, Ruidan; Gu, Genda; Plugge, Stephan; Tummuru, Tarun; Kim, Miyoung; Franz, Marcel; Pixley, Jedediah H.; Poccia, Nicola; Kim, Philip
• 署名单位: Harvard University; Rutgers University System; Rutgers University New Brunswick; University of Connecticut; Sogang University; Seoul National University (SNU); Harvard University; United States Department of Energy (DOE); Brookhaven National Laboratory; University of British Columbia; University of British Columbia; Shanghai Jiao Tong University; Shanghai Jiao Tong University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-13273
• DOI: 10.1126/science.abl8371
• 发表日期: 2023-12-22
• 页码: 1422-1427
• 关键词: intrinsic josephson-junctions; zero-voltage state; grain-boundaries; shapiro steps; bi2sr2cacu2o8+delta; TRANSITION; BEHAVIOR; field; oscillations; stacks

摘要

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