Antiferromagnetic phase transition in a 3D fermionic Hubbard model

• 成果类型: Article
• 署名作者: Shao, Hou-Ji; Wang, Yu-Xuan; Zhu, De-Zhi; Zhu, Yan-Song; Sun, Hao-Nan; Chen, Si-Yuan; Zhang, Chi; Fan, Zhi-Jie; Deng, Youjin; Yao, Xing-Can; Chen, Yu-Ao; Pan, Jian-Wei
• 署名单位: Chinese Academy of Sciences; University of Science & Technology of China, CAS; Chinese Academy of Sciences; University of Science & Technology of China, CAS; Chinese Academy of Sciences; University of Science & Technology of China, CAS; Chinese Academy of Sciences; University of Science & Technology of China, CAS; Hefei National Laboratory; Chinese Academy of Sciences; University of Science & Technology of China, CAS
• 刊物名称: Nature
• ISSN/ISSBN: 0028-4143
• DOI: 10.1038/s41586-024-07689-2
• 发表日期: 2024-08-08
• 关键词: high-temperature superconductors; mott insulator; atoms; physics; simulations; gases

摘要

The fermionic Hubbard model (FHM)1 describes a wide range of physical phenomena resulting from strong electron-electron correlations, including conjectured mechanisms for unconventional superconductivity. Resolving its low-temperature physics is, however, challenging theoretically or numerically. Ultracold fermions in optical lattices2,3 provide a clean and well-controlled platform offering a path to simulate the FHM. Doping the antiferromagnetic ground state of a FHM simulator at half-filling is expected to yield various exotic phases, including stripe order4, pseudogap5, and d-wave superfluid6, offering valuable insights into high-temperature superconductivity7-9. Although the observation of antiferromagnetic correlations over short10 and extended distances11 has been obtained, the antiferromagnetic phase has yet to be realized as it requires sufficiently low temperatures in a large and uniform quantum simulator. Here we report the observation of the antiferromagnetic phase transition in a three-dimensional fermionic Hubbard system comprising lithium-6 atoms in a uniform optical lattice with approximately 800,000 sites. When the interaction strength, temperature and doping concentration are finely tuned to approach their respective critical values, a sharp increase in the spin structure factor is observed. These observations can be well described by a power-law divergence, with a critical exponent of 1.396 from the Heisenberg universality class12. At half-filling and with optimal interaction strength, the measured spin structure factor reaches 123(8), signifying the establishment of an antiferromagnetic phase. Our results provide opportunities for exploring the low-temperature phase diagram of the FHM. Antiferromagnetic phase transition is observed in a three-dimensional fermionic Hubbard system comprising lithium-6 atoms in a uniform optical lattice with approximately 800,000 sites.