Letter | Published:

Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit

Nature volume 546, pages 270273 (08 June 2017) | Download Citation

Abstract

Since the discovery of graphene1, the family of two-dimensional materials has grown, displaying a broad range of electronic properties. Recent additions include semiconductors with spin–valley coupling2, Ising superconductors3,4,5 that can be tuned into a quantum metal6, possible Mott insulators with tunable charge-density waves7, and topological semimetals with edge transport8,9. However, no two-dimensional crystal with intrinsic magnetism has yet been discovered10,11,12,13,14; such a crystal would be useful in many technologies from sensing to data storage15. Theoretically, magnetic order is prohibited in the two-dimensional isotropic Heisenberg model at finite temperatures by the Mermin–Wagner theorem16. Magnetic anisotropy removes this restriction, however, and enables, for instance, the occurrence of two-dimensional Ising ferromagnetism. Here we use magneto-optical Kerr effect microscopy to demonstrate that monolayer chromium triiodide (CrI3) is an Ising ferromagnet with out-of-plane spin orientation. Its Curie temperature of 45 kelvin is only slightly lower than that of the bulk crystal, 61 kelvin, which is consistent with a weak interlayer coupling. Moreover, our studies suggest a layer-dependent magnetic phase, highlighting thickness-dependent physical properties typical of van der Waals crystals17,18,19. Remarkably, bilayer CrI3 displays suppressed magnetization with a metamagnetic effect20, whereas in trilayer CrI3 the interlayer ferromagnetism observed in the bulk crystal is restored. This work creates opportunities for studying magnetism by harnessing the unusual features of atomically thin materials, such as electrical control for realizing magnetoelectronics12, and van der Waals engineering to produce interface phenomena15.

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References

  1. 1.

    et al. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004)

  2. 2.

    , , & Spin and pseudospins in layered transition metal dichalcogenides. Nat. Phys. 10, 343–350 (2015)

  3. 3.

    et al. Superconductivity protected by spin-valley locking in ion-gated MoS2. Nat. Phys. 12, 144–149 (2016)

  4. 4.

    et al. Evidence for two-dimensional Ising superconductivity in gated MoS2. Science 350, 1353–1357 (2015)

  5. 5.

    et al. Ising pairing in superconducting NbSe2 atomic layers. Nat. Phys. 12, 139–143 (2015)

  6. 6.

    et al. Nature of the quantum metal in a two-dimensional crystalline superconductor. Nat. Phys. 12, 208–212 (2015)

  7. 7.

    et al. Gate-tunable phase transitions in thin flakes of 1T-TaS2. Nat. Nanotechnol. 10, 270–276 (2015)

  8. 8.

    et al. Topological insulator behavior in monolayer WTe2. Preprint at (2016)

  9. 9.

    , , & Quantum spin Hall effect in two-dimensional transition metal dichalcogenides. Science 346, 1344–1347 (2014)

  10. 10.

    , , & Coupling of crystal structure and magnetism in the layered, ferromagnetic insulator CrI3. Chem. Mater. 27, 612–620 (2015)

  11. 11.

    & CrXTe3 (X = Si, Ge) nanosheets: two dimensional intrinsic ferromagnetic semiconductors. J. Mater. Chem. C 2, 7071–7076 (2014)

  12. 12.

    , , & Robust intrinsic ferromagnetism and half semiconductivity in stable two-dimensional single-layer chromium trihalides. J. Mater. Chem. C 3, 12457–12468 (2015)

  13. 13.

    et al. Ultrathin nanosheets of CrSiTe3: a semiconducting two-dimensional ferromagnetic material. J. Mater. Chem. C 4, 315–322 (2016)

  14. 14.

    , , , & Magnetic ground state of semiconducting transition-metal trichalcogenide monolayers. Phys. Rev. B 91, 235425 (2015)

  15. 15.

    , , & Emergent phenomena induced by spin–orbit coupling at surfaces and interfaces. Nature 539, 509–517 (2016)

  16. 16.

    & Absence of ferromagnetism or antiferromagnetism in one- or two-dimensional isotropic Heisenberg models. Phys. Rev. Lett. 17, 1133–1136 (1966)

  17. 17.

    et al. Unconventional quantum Hall effect and Berry’s phase of 2π in bilayer graphene. Nat. Phys. 2, 177–180 (2006)

  18. 18.

    , , , & Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010)

  19. 19.

    et al. Emerging photoluminescence in monolayer MoS2. Nano Lett. 10, 1271–1275 (2010)

  20. 20.

    & Metamagnetism. Adv. Phys. 26, 487–650 (1977)

  21. 21.

    , , & Magnetism in the few-monolayers limit: a surface magneto-optic Kerr-effect study of the magnetic behavior of ultrathin films of Co, Ni, and Co-Ni alloys on Cu(100) and Cu(111). Phys. Rev. B 49, 3962–3971 (1994)

  22. 22.

    et al. Experimental confirmation of universality for a phase transition in two dimensions. Nature 378, 597–600 (1995)

  23. 23.

    , & Critical behavior of the uniaxial ferromagnetic monolayer Fe(110) on W(110). Phys. Rev. B 54, 15224–15233 (1996)

  24. 24.

    & Experiments on simple magnetic model systems. Adv. Phys. 50, 947–1170 (1974)

  25. 25.

    , & 2D Ising-like ferromagnetic behaviour for the lamellar Cr2Si2Te6 compound: a neutron scattering investigation. Europhys. Lett. 29, 251 (1995)

  26. 26.

    , , , & Ferromagnetic two-dimensional crystals: single layers of K2CuF4. Phys. Rev. B 88, 201402 (2013)

  27. 27.

    et al. Raman spectroscopy of atomically thin two-dimensional magnetic iron phosphorus trisulfide (FePS3) crystals. 2D Mater. 3, 031009 (2016)

  28. 28.

    , , , & Magneto-elastic coupling in a potential ferromagnetic 2D atomic crystal. 2D Mater. 3, 025035 (2016)

  29. 29.

    & Magnetization, resonance, and optical properties of the ferromagnet CrI3. J. Appl. Phys. 36, 1259 (1965)

  30. 30.

    The magnetic anisotropy and spin reorientation of nanostructures and nanoscale films. J. Phys. Condens. Matter 16, R603 (2004)

  31. 31.

    Measurement of magneto-optical Kerr effect using piezo-birefringent modulator. Jpn. J. Appl. Phys. 20, 2403 (1981)

  32. 32.

    , & The reflectivity spectra of some group VA transition metal dichalcogenides. J. Phys. C 8, 4236 (1975)

  33. 33.

    et al. Fast and reliable identification of atomically thin layers of TaSe2 crystals. Nano Res. 6, 191–199 (2013)

  34. 34.

    et al. Making graphene visible. Appl. Phys. Lett. 91, 063124 (2007)

  35. 35.

    & Optical properties of chromium trihalides in the region 1-11 eV. Bull. Am. Phys. Soc. II 13, 3 (1968)

  36. 36.

    et al. Ellipsometric determination of optical constants for silicon and thermally grown silicon dioxide via a multi-sample, multi-wavelength, multi-angle investigation. J. Appl. Phys. 83, 3323 (1998)

  37. 37.

    Magneto-optical effects in transition metal systems. Rep. Prog. Phys. 59, 1665–1735 (1996)

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Acknowledgements

Work at the University of Washington was mainly supported by the Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division (DE-SC0008145 and SC0012509), and a University of Washington Innovation Award. Work at the Massachusetts Institute of Technology was supported by the Center for Integrated Quantum Materials under NSF grant DMR-1231319 as well as the Gordon and Betty Moore Foundation’s EPiQS Initiative (grant GBMF4541 to P.J.-H.). Device fabrication was supported in part by the Center for Excitonics, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award Number DESC0001088. D.H.C.’s contribution is supported by DE-SC0002197. Work at Carnegie Mellon University is supported by DOE BES DE-SC0012509. W.Y. is supported by the Croucher Foundation (Croucher Innovation Award), the RGC of Hong Kong (HKU17305914P), and the HKU ORA. Work at Oak Ridge National Laboratory (M.A.M.) was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. X.X. and D.X. acknowledge the support of a Cottrell Scholar Award. X.X. acknowledges the support from the Clean Energy Institute (funded by the State of Washington) and from a Boeing Distinguished Professorship in Physics.

Author information

Author notes

    • Bevin Huang
    • , Genevieve Clark
    •  & Efrén Navarro-Moratalla

    These authors contributed equally to this work.

Affiliations

  1. Department of Physics, University of Washington, Seattle, Washington 98195, USA

    • Bevin Huang
    • , Kyle L. Seyler
    • , Ding Zhong
    • , Emma Schmidgall
    • , David H. Cobden
    •  & Xiaodong Xu
  2. Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA

    • Genevieve Clark
    •  & Xiaodong Xu
  3. Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

    • Efrén Navarro-Moratalla
    • , Dahlia R. Klein
    •  & Pablo Jarillo-Herrero
  4. Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA

    • Ran Cheng
    •  & Di Xiao
  5. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

    • Michael A. McGuire
  6. Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China

    • Wang Yao

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Contributions

X.X. and P.J.-H. supervised the project. E.N.-M. and M.A.M. synthesized and characterized the bulk CrI3 crystal. E.N.-M. and D.R.K. fabricated the samples and analysed the layer thickness, assisted by G.C. and B.H. B.H. built the MOKE setup with help from E.S. and D.Z. G.C. and B.H. performed the MOKE measurements, assisted by K.L.S. and E.N.-M. R.C., D.X. and W.Y. provided theoretical support. B.H., G.C., E.N.-M., X.X., P.J.-H., D.X. and D.H.C. wrote the paper with input from all authors. All authors discussed the results.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Pablo Jarillo-Herrero or Xiaodong Xu.

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DOI

https://doi.org/10.1038/nature22391

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