Letter | Published:

Valley magnetoelectricity in single-layer MoS2

Nature Materials volume 16, pages 887891 (2017) | Download Citation

Abstract

The magnetoelectric (ME) effect, the phenomenon of inducing magnetization by application of an electric field or vice versa, holds great promise for magnetic sensing and switching applications1. Studies of the ME effect have so far focused on the control of the electron spin degree of freedom (DOF) in materials such as multiferroics2 and conventional semiconductors3. Here, we report a new form of the ME effect based on the valley DOF in two-dimensional Dirac materials4,5,6. By breaking the three-fold rotational symmetry in single-layer MoS 2 via a uniaxial stress, we have demonstrated the pure electrical generation of valley magnetization in this material, and its direct imaging by Kerr rotation microscopy. The observed out-of-plane magnetization is independent of in-plane magnetic field, linearly proportional to the in-plane current density, and optimized when the current is orthogonal to the strain-induced piezoelectric field. These results are fully consistent with a theoretical model of valley magnetoelectricity driven by Berry curvature effects. Furthermore, the effect persists at room temperature, opening possibilities for practical valleytronic devices.

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Acknowledgements

We acknowledge W. Shan, D. Xiao, I. Sodemann and L. Fu for fruitful discussions. The research was supported by the National Science Foundation DMR-1420451 for sample and device fabrication and the US Department of Energy, Office of Basic Energy Sciences under award no. DESC0013883 and the Air Force Office of Scientific Research under grant FA9550-14-1-0268 for optical spectroscopy measurements. Support for data analysis and modelling was provided by the Air Force Office of Scientific Research under grant FA9550-16-1-0249 (K.F.M.) and the National Science Foundation DMR-1410407 (J.S.). This work was also supported by the National Research Foundation of Korea Grant funded by the Korean government (S2017A040300024) (J.L.) and a David and Lucille Packard Fellowship and a Sloan Fellowship (K.F.M.).

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Affiliations

  1. Department of Physics and Center for 2-Dimensional and Layered Materials, the Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA

    • Jieun Lee
    • , Zefang Wang
    • , Hongchao Xie
    • , Kin Fai Mak
    •  & Jie Shan
  2. Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, Gyeonggi-do 16499, Korea

    • Jieun Lee

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Contributions

J.L., K.F.M. and J.S. conceived and designed the experiments, analysed the data and co-wrote the manuscript. J.L., Z.W. and H.X. fabricated the devices and performed the measurements. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Kin Fai Mak or Jie Shan.

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DOI

https://doi.org/10.1038/nmat4931

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