Utilization of the interaction between spin and heat currents is the central focus of the field of spin caloritronics. Chiral phonons possessing angular momentum arising from the broken symmetry of a non-magnetic material create the potential for generating spin currents at room temperature in response to a thermal gradient, precluding the need for a ferromagnetic contact. Here we show the observation of spin currents generated by chiral phonons in a two-dimensional layered hybrid organic–inorganic perovskite implanted with chiral cations when subjected to a thermal gradient. The generated spin current shows a strong dependence on the chirality of the film and external magnetic fields, of which the coefficient is orders of magnitude larger than that produced by the reported spin Seebeck effect. Our findings indicate the potential of chiral phonons for spin caloritronic applications and offer a new route towards spin generation in the absence of magnetic materials.
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Source data are provided with this paper. The source data for the Supplementary Information are available from the corresponding author upon reasonable request.
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J.L. acknowledges the financial support from the National Science Foundation under award number CBET 1943813 for the ultrafast measurements, thermal characterizations and thermal modelling. D.S. acknowledges the financial support provided by the US Department of Energy, Office of Science, under the grant number DE-SC0020992 for the device fabrications. D.S. and W.Y. acknowledge the support through the Center for Hybrid Organic–Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences for material synthesis, thin-film preparations and magnetic characterizations. J.L. acknowledges partial financial support from the North Carolina Space Grant New Investigator Award for the student aids. D.S. and J.L. also acknowledge the partial financial support from the North Carolina State University Research and Innovation Seed Funding for the student aids. The X-ray diffraction of the perovskite thin films in this work was performed at the Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), which is supported by the National Science Foundation, grant ECCS-1542015, as part of the National Nanotechnology Coordinated Infrastructure (NNCI). The circular dichroism measurements were performed at the UNC Macromolecular Interactions Facility supported by the National Cancer Institute of the National Institutes of Health under award number P30CA016086.
The authors declare no competing interests.
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Supplementary Discussion, Figs. 1–22 and Tables 1–5.
Supplementary Video 1
The time-dependent spin current is visualized with different applied external magnetic fields.
Source Data Fig. 2
Source data for transient and spatial temperature in Fig. 2a–c; transient Kerr rotation signals in Fig. 2d.
Source Data Fig. 3
Source data for transient Kerr rotation signals plotted in Fig. 3b–f.
Source Data Fig. 4
Source data for transient MOKE data plotted in Fig. 4a–e.
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Kim, K., Vetter, E., Yan, L. et al. Chiral-phonon-activated spin Seebeck effect. Nat. Mater. 22, 322–328 (2023). https://doi.org/10.1038/s41563-023-01473-9