Abstract
In recent years, research on spin ordering phenomena has broadened to include intermolecular exchange interactions in organic–inorganic crystals and goes beyond the traditional focus on interatomic interactions. However, a crystallized framework used for stabilizing parallel spin alignment through an ordered lattice is indispensable to ferromagnetism. Here we demonstrate room-temperature ferromagnetic order in two-dimensional confined molecule-based monolayers. The confinement effect of the van der Waals interlayer space enables cobaltocene molecules to self-assemble into a monolayer with a honeycomb-like configuration. The spontaneous uniform spin orientation—ferromagnetic coupling—is established by an intermolecular vibronic superexchange interaction, involving a cooperative dynamic Jahn–Teller effect in the confined cobaltocene monolayer. The molecular cobaltocene monolayers exhibit a ferromagnetic transition temperature above room temperature and have a large saturation magnetization.
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Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (grant nos. 21925110, U2032161, 21890751, 22272158, 22303092, 22225301 and 22321001), the National Key R&D Program on Nano Science & Technology of the Ministry of Science and Technology, China (grant no. 2022YFA1203601), the China Academy of Sciences (CAS) Project for Young Scientists in Basic Research (grant no. YSBR-070), University of Science & Technology of China (USTC) Research Funds of the Double First-Class Initiative (grant no. YD2060002004), the Youth Innovation Promotion Association, CAS (grant no. 2018500), the Strategic Priority Research Program, CAS (grant nos. XDB36000000 and XDB0450101), the Innovation Program for Quantum Science and Technology (grant no. 2021ZD0303302), the Key R&D Program of Shandong Province (grant no. 2021CXGC010302), the Users with Excellence Project of Hefei Science Center, CAS (grant no. 2021HSC-UE004), and the National Postdoctoral Program for Innovative Talents (grant nos. BX20190307 and BX20190308). We appreciate the support from beamline 1W1B of the Beijing Synchrotron Radiation Facility, Beijing, China, and beamlines BL12B-a and BL11U of the NSRL, Hefei, China. We thank the electron microscopy facility of the Cryo-EM Centre of USTC for their support and the super computer centres of USTC and CAS for their support. This work was partially carried out at the USTC Centre for Micro and Nanoscale Research and Fabrication.
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C.W. conceived the idea, experimentally realized the study, co-wrote the paper, supervised the entire project and is responsible for the infrastructure and project direction. Y.G. designed and experimentally realized the study, co-wrote the paper and supervised the entire project. Yuhua Liu, H.L., B.Y. and Yang Liu contributed equally to this work; they experimentally realized the study, analysed the data and co-wrote the paper. These works were assisted by J.P., Y.S., Y.Q., K.C., W.C., W.Y. and J.Z. The HAADF-STEM data collection was performed by Y. Lin. and X.T. Theoretical calculations were carried out by H.L. and X.W., Y.X. supervised the whole experimental procedure and co-wrote the paper. All authors discussed the results and commented on and revised the paper.
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Liu, Y., Lv, H., Yuan, B. et al. Room-temperature long-range ferromagnetic order in a confined molecular monolayer. Nat. Phys. 20, 281–286 (2024). https://doi.org/10.1038/s41567-023-02312-z
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DOI: https://doi.org/10.1038/s41567-023-02312-z
