Large exchange splitting in monolayer graphene magnetized by an antiferromagnet

Abstract

Spin splitting in graphene is required to develop graphene-based multifunctional spintronic devices with low dissipation and long-distance spin transport. Magnetic proximity effects are a promising route to realize exchange splitting in the material, which is otherwise intrinsically non-spin-polarized. Here, we show that monolayer graphene can be magnetized by coupling to an antiferromagnetic thin film of chromium selenide, resulting in an exchange splitting energy as high as 134 meV at 2 K. This exchange splitting is shown through shifts in the quantum Hall plateau and quantum oscillations in the graphene, and its energy can be modulated through field cooling, with the exchange splitting energy increasing with positive field cooling and decreasing with negative field cooling. Our experimental demonstration of magnetism in graphene at low temperatures is supported by measurements of resistivity dependence on temperature and magneto-optic Kerr measurements.

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Fig. 1: Characterizations of the AFM and graphene/AFM heterostructure.
Fig. 2: Quantum Hall plateau and quantum oscillations shifted by field cooling.
Fig. 3: Shifts of quantum Hall plateaux and quantum oscillations modulated by AFM.
Fig. 4: Magnetic phase transition from transport measurements and the MOKE signal.

Data availability

The data that support the plots within this paper and other findings of this study are available in figshare with the identifier 10.6084/m9.figshare.12331154 (https://figshare.com/articles/dataset/source-data-for-Gr-CrSe-paper_xlsx/12331154).

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Acknowledgements

The transport measurement and theoretical modelling in this work were supported by Spins and Heat in Nanoscale Electronic Systems (SHINES), an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under award #SC0012670. We are also grateful for support from the National Science Foundation (NSF) (DMR-1411085 and DMR-1810163) and the ARO programme (contract no. W911NF-15-1-10561). Research was performed in part at the NIST Center for Nanoscale Science and Technology. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by NSF grant no. OCI-1053575. Specifically, it used the Bridges system (supported by NSF award no. ACI-1445606) at the Pittsburgh Supercomputing Center (PSC). Certain commercial equipment, instruments or materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

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Contributions

Y.W., G.Y. and K.L.W. conceived and designed the experiment. K.L.W. supervised the work. L.P. grew the CrSe samples. Y.W. carried out the fabrication and transport measurements. G.Y. and A. Lee performed the theoretical calculations and machine learning. A.J.G., D.A.G., J.A.B. and W.R.II performed and analysed the X-ray spectroscopy and neutron diffraction. Q.P. performed the MOKE measurements. A. Li and X. Han performed the transmission electron microscopy measurement. All authors contributed to the measurement and analyses. Y.W., G.Y., A.J.G. and K.L.W. wrote the manuscript with contributions from all the authors.

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Correspondence to Kang L. Wang.

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Supplementary Figs. 1–10 and Sections A–K.

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Wu, Y., Yin, G., Pan, L. et al. Large exchange splitting in monolayer graphene magnetized by an antiferromagnet. Nat Electron 3, 604–611 (2020). https://doi.org/10.1038/s41928-020-0458-0

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