Two-dimensional heavy fermions in the van der Waals metal CeSiI

• 成果类型: Article
• 署名作者: Posey, Victoria A.; Turkel, Simon; Rezaee, Mehdi; Devarakonda, Aravind; Kundu, Asish K.; Ong, Chin Shen; Thinel, Morgan; Chica, Daniel G.; Vitalone, Rocco A.; Jing, Ran; Xu, Suheng; Needell, David R.; Meirzadeh, Elena; Feuer, Margalit L.; Jindal, Apoorv; Cui, Xiaomeng; Valla, Tonica; Thunstrom, Patrik; Yilmaz, Turgut; Vescovo, Elio; Graf, David; Zhu, Xiaoyang; Scheie, Allen; May, Andrew F.; Eriksson, Olle; Basov, D. N.; Dean, Cory R.; Rubio, Angel; Kim, Philip; Ziebel, Michael E.; Millis, Andrew J.; Pasupathy, Abhay N.; Roy, Xavier
• 署名单位: Columbia University; Columbia University; United States Department of Energy (DOE); Brookhaven National Laboratory; Harvard University; Uppsala University; United States Department of Energy (DOE); Brookhaven National Laboratory; State University System of Florida; Florida State University; United States Department of Energy (DOE); Oak Ridge National Laboratory; United States Department of Energy (DOE); Los Alamos National Laboratory; United States Department of Energy (DOE); Oak Ridge National Laboratory; Uppsala University; Max Planck Society; European Theoretical Spectroscopy Facility (ETSF); University of Basque Country; Simons Foundation; Flatiron Institute
• 刊物名称: Nature
• ISSN/ISSBN: 0028-6319
• DOI: 10.1038/s41586-023-06868-x
• 发表日期: 2024-01-18
• 关键词: exchange interactions; electronic-structure; quantum criticality; crystal-field; kondo-lattice; superconductivity; pseudopotentials; magnetism

摘要

Heavy-fermion metals are prototype systems for observing emergent quantum phases driven by electronic interactions1-6. A long-standing aspiration is the dimensional reduction of these materials to exert control over their quantum phases7-11, which remains a significant challenge because traditional intermetallic heavy-fermion compounds have three-dimensional atomic and electronic structures. Here we report comprehensive thermodynamic and spectroscopic evidence of an antiferromagnetically ordered heavy-fermion ground state in CeSiI, an intermetallic comprising two-dimensional (2D) metallic sheets held together by weak interlayer van der Waals (vdW) interactions. Owing to its vdW nature, CeSiI has a quasi-2D electronic structure, and we can control its physical dimension through exfoliation. The emergence of coherent hybridization of f and conduction electrons at low temperature is supported by the temperature evolution of angle-resolved photoemission and scanning tunnelling spectra near the Fermi level and by heat capacity measurements. Electrical transport measurements on few-layer flakes reveal heavy-fermion behaviour and magnetic order down to the ultra-thin regime. Our work establishes CeSiI and related materials as a unique platform for studying dimensionally confined heavy fermions in bulk crystals and employing 2D device fabrication techniques and vdW heterostructures12 to manipulate the interplay between Kondo screening, magnetic order and proximity effects. We present comprehensive thermodynamic and spectroscopic evidence for an antiferromagnetically ordered heavy-fermion ground state in the van der Waals metal CeSiI.