Exciton-driven antiferromagnetic metal in a correlated van der Waals insulator

Journal Article · 10 August 2021 · Nature Communications

DOI: https://doi.org/10.1038/s41467-021-25164-8 · OSTI ID:1812556

Belvin, Carina A. ; Baldini, Edoardo ; Ozel, Ilkem Ozge; Mao, Dan; Po, Hoi Chun; Allington, Clifford J. ; Son, Suhan; Kim, Beom Hyun; Kim, Jonghyeon ; Hwang, Inho; Kim, Jae Hoon ; Park, Je-Geun ; Senthil, T.; Gedik, Nuh

Abstract Collective excitations of bound electron-hole pairs—known as excitons—are ubiquitous in condensed matter, emerging in systems as diverse as band semiconductors, molecular crystals, and proteins. Recently, their existence in strongly correlated electron materials has attracted increasing interest due to the excitons’ unique coupling to spin and orbital degrees of freedom. The non-equilibrium driving of such dressed quasiparticles offers a promising platform for realizing unconventional many-body phenomena and phases beyond thermodynamic equilibrium. Here, we achieve this in the van der Waals correlated insulator NiPS ₃ by photoexciting its newly discovered spin–orbit-entangled excitons that arise from Zhang-Rice states. By monitoring the time evolution of the terahertz conductivity, we observe the coexistence of itinerant carriers produced by exciton dissociation and a long-wavelength antiferromagnetic magnon that coherently precesses in time. These results demonstrate the emergence of a transient metallic state that preserves long-range antiferromagnetism, a phase that cannot be reached by simply tuning the temperature. More broadly, our findings open an avenue toward the exciton-mediated optical manipulation of magnetism.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: Gordon and Betty More Foundation EPiQS Initiative; Institute for Basic Science; National Research Foundation of Korea; National Science Foundation (NSF); Swiss National Science Foundation; USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
• Grant/Contract Number: SC0008739
• OSTI ID: 1812556
• Journal Information: Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 12; ISSN 2041-1723
• Publisher: Nature Publishing GroupCopyright Statement
• Country of Publication: United Kingdom
• Language: English