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Electrical and thermal generation of spin currents by magnetic bilayer graphene

Abstract

Ultracompact spintronic devices greatly benefit from the implementation of two-dimensional materials that provide large spin polarization of charge current together with long-distance transfer of spin information. Here spin-transport measurements in bilayer graphene evidence a strong spin–charge coupling due to a large induced exchange interaction by the proximity of an interlayer antiferromagnet (CrSBr). This results in the direct detection of the spin polarization of conductivity (up to 14%) and a spin-dependent Seebeck effect in the magnetic graphene. The efficient electrical and thermal spin–current generation is the most technologically relevant aspect of magnetism in graphene, controlled here by the antiferromagnetic dynamics of CrSBr. The high sensitivity of spin transport in graphene to the magnetization of the outermost layer of the adjacent antiferromagnet, furthermore, enables the read-out of a single magnetic sublattice. The combination of gate-tunable spin-dependent conductivity and Seebeck coefficient with long-distance spin transport in a single two-dimensional material promises ultrathin magnetic memory and sensory devices based on magnetic graphene.

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Fig. 1: Induced magnetism in bilayer graphene by the proximity of CrSBr.
Fig. 2: Spin transport in bilayer graphene with spin-polarized conductivity.
Fig. 3: SDSE in the magnetized bilayer graphene.
Fig. 4: Temperature dependence of the spin signal.
Fig. 5: AHE in a bilayer graphene/CrSBr vdW heterostructure.

Data availability

The authors declare that all data supporting the findings of this study are available within the paper and its Supplementary Information. Any further related information can be provided by the corresponding author upon reasonable request. Source data are provided with this paper.

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Acknowledgements

We thank M. H. D. Guimarães and E. J. Telford for discussions and T. J. Schouten, H. Adema, H. de Vries, A. Joshua and J. G. Holstein for technical support. This research received funding from the Dutch Foundation for Fundamental Research on Matter (FOM) as a part of the Netherlands Organisation for Scientific Research (NWO), FLAG-ERA (15FLAG01-2), the European Union’s Horizon 2020 research and innovation programme under grant agreements no. 785219 and no. 881603 (Graphene Flagship Core 2 and Core 3), NanoNed, the Zernike Institute for Advanced Materials and the Spinoza Prize awarded in 2016 to B.J.v.W. by NWO. Synthesis, structural characterization and magnetic measurements are supported as part of Programmable Quantum Materials, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under award DE-SC0019443. A.H.D. is supported by the NSF graduate research fellowship program (DGE 16-44869).

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T.S.G. and B.J.v.W. conceived the project. T.S.G. fabricated the devices and performed the main experiments and data analysis with the help of A.A.K. and supervision of B.J.v.W. A.A.K. performed the analytical modelling. T.S.G. and D.K.d.W. performed the measurements and data analysis of the AHE. A.H.D. and X.R. synthesized the CrSBr crystals and performed the SQUID magnetometry and analysis. T.S.G. wrote the manuscript and Supplementary Information with help from A.A.K. All the authors discussed the results and commented on the manuscript.

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Correspondence to Talieh S. Ghiasi.

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Ghiasi, T.S., Kaverzin, A.A., Dismukes, A.H. et al. Electrical and thermal generation of spin currents by magnetic bilayer graphene. Nat. Nanotechnol. 16, 788–794 (2021). https://doi.org/10.1038/s41565-021-00887-3

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