Following the recent isolation of monolayer CrI3 (ref. 1), many more two-dimensional van der Waals magnetic materials have been isolated2,3,4,5,6,7,8,9,10,11,12. Their incorporation in van der Waals heterostructures offers a new platform for spintronics5,6,7,8,9, proximity magnetism13 and quantum spin liquids14. A primary question in this field is how exfoliating crystals to the few-layer limit influences their magnetism. Studies of CrI3 have shown a different magnetic ground state for ultrathin exfoliated films1,5,6 compared with the bulk, but the origin is not yet understood. Here, we use electron tunnelling through few-layer crystals of the layered antiferromagnetic insulator CrCl3 to probe its magnetic order and find a tenfold enhancement of the interlayer exchange compared with bulk crystals. Moreover, temperature- and polarization-dependent Raman spectroscopy reveals that the crystallographic phase transition of bulk crystals does not occur in exfoliated films. This results in a different low-temperature stacking order and, we hypothesize, increased interlayer exchange. Our study provides insight into the connection between stacking order and interlayer interactions in two-dimensional magnets, which may be relevant for correlating stacking faults and mechanical deformations with the magnetic ground states of other more exotic layered magnets such as RuCl3 (ref. 14).
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The data that support the findings of this study are available at https://dataverse.harvard.edu/dataverse/crcl3.
Huang, B. et al. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature 546, 270–273 (2017).
Gong, C. et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. Nature 546, 265–269 (2017).
Huang, B. et al. Electrical control of 2D magnetism in bilayer CrI3. Nat. Nanotechnol. 13, 544–548 (2018).
Seyler, K. L. et al. Ligand-field helical luminescence in a 2D ferromagnetic insulator. Nat. Phys. 14, 277–281 (2018).
Klein, D. R. et al. Probing magnetism in 2D van der Waals crystalline insulators via electron tunneling. Science 360, 1218–1222 (2018).
Song, T. et al. Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures. Science 360, 1214–1218 (2018).
Wang, Z. et al. Very large tunneling magnetoresistance in layered magnetic semiconductor CrI3. Nat. Commun. 9, 2516 (2018).
Kim, H. H. et al. One million percent tunnel magnetoresistance in a magnetic van der Waals heterostructure. Nano Lett. 18, 4885–4890 (2018).
Ghazaryan, D. et al. Magnon-assisted tunneling in van der Waals heterostructures based on CrBr3. Nat. Electron. 1, 344–349 (2018).
Kuo, C.-T. et al. Exfoliation and Raman spectroscopic fingerprint of few-layer NiPS3 van der Waals crystals. Sci. Rep. 6, 20904 (2016).
Lee, J.-U. et al. Ising-type magnetic ordering in atomically thin FePS3. Nano Lett. 16, 7433–7438 (2016).
Burch, K. S., Mandrus, D. & Park, J.-G. Magnetism in two-dimensional van der Waals materials. Nature 563, 47–52 (2018).
Zhong, D. et al. Van der Waals engineering of ferromagnetic semiconductor heterostructures for spin and valleytronics. Sci. Adv. 3, e1603113 (2017).
Banerjee, A. et al. Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet. Nat. Mater. 15, 733–740 (2016).
Dillon, J. F. & Olson, C. E. Magnetization, resonance, and optical properties of the ferromagnet CrI3. J. Appl. Phys. 36, 1259–1260 (1965).
Cable, J. W. et al. Neutron diffraction investigation of antiferromagnetism in CrCl3. J. Phys. Chem. Solids 19, 29–34 (1961).
Narath, A. & Davis, H. L. Spin-wave analysis of the sublattice magnetization behavior of antiferromagnetic and ferromagnetic CrCl3. Phys. Rev. 137, A163–A178 (1965).
Kuhlow, B. Magnetic ordering in CrCl3 at the phase transition. Phys. Status Solidi A 72, 161–168 (1982).
McGuire, M. A. et al. Magnetic behavior and spin-lattice coupling in cleavable van der Waals layered CrCl3. Cryst. Phys. Rev. Mater. 1, 014001 (2017).
McGuire, M. A., Dixit, H., Cooper, V. R. & Sales, B. C. Coupling of crystal structure and magnetism in the layered, ferromagnetic insulator CrI3. Chem. Mater. 27, 612–620 (2015).
McGuire, M. A. Crystal and magnetic structures in layered, transition metal dihalides and trihalides. Crystals 7, 121 (2017).
MacNeill, D. et al. Gigahertz frequency antiferromagnetic resonance and strong magnon–magnon coupling in the layered crystal CrCl3. Phys. Rev. Lett. 123, 047204 (2019).
Jiang, S. et al. Controlling magnetism in 2D CrI3 by electrostatic doping. Nat. Nanotechnol. 13, 549–553 (2018).
Thiel, L. et al. Probing magnetism in 2D materials at the nanoscale with single spin microscopy. Science 364, 973–976 (2019).
Jiang, P. et al. Stacking tunable interlayer magnetism in bilayer CrI3. Phys. Rev. B 99, 144401 (2019).
Soriano, D. et al. Interplay between interlayer exchange and stacking in CrI3 bilayers. Solid State Commun. 299, 113662 (2019).
Sivadas, N. et al. Stacking-dependent magnetism in bilayer CrI3. Nano Lett. 18, 7658–7664 (2018).
Simmons, J. G. Generalized formula for the electric tunnel effect between similar electrodes separated by a thin insulating film. J. Appl. Phys. 34, 1793–1803 (1963).
Miao, G.-X., Müller, M. & Moodera, J. S. Magnetoresistance in double spin filter tunnel junctions with nonmagnetic electrodes and its unconventional bias dependence. Phys. Rev. Lett. 102, 076601 (2009).
Moodera, J. S., Meservey, R. & Hao, X. Variation of the electron-spin polarization in EuSe tunnel junctions from zero to near 100% in a magnetic field. Phys. Rev. Lett. 70, 853–856 (1993).
Worledge, D. C. & Geballe, T. H. Magnetoresistive double spin filter tunnel junction. J. Appl. Phys. 88, 5277–5279 (2000).
Hao, X., Moodera, J. S. & Meservey, R. Spin-filter effect of ferromagnetic europium sulfide tunnel barriers. Phys. Rev. B 42, 8235–8243 (1990).
Glamazda, A. et al. Relation between Kitaev magnetism and structure in α-RuCl3. Phys. Rev. B 95, 174429 (2017).
Cao, H. B. et al. Low-temperature crystal and magnetic structure of α-RuCl3. Phys. Rev. B 93, 134423 (2016).
Bermudez, V. M. Unit-cell vibrational spectra of chromium trichloride and chromium tribromide. Solid State Commun. 19, 693–697 (1976).
Larson, D. T. & Kaxiras, E. Raman spectrum of CrI3: an ab initio study. Phys. Rev. B 98, 085406 (2018).
Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018).
Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).
Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).
Perdew, J. P. & Zunger, A. Self-interaction correction to density-functional approximations for many-electron systems. Phys. Rev. B 23, 5048–5079 (1981).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Klimeš, J., Bowler, D. R. & Michaelides, A. Chemical accuracy for the van der Waals density functional. J. Phys. Condens. Matter 22, 022201 (2010).
Klimeš, J., Bowler, D. R. & Michaelides, A. Van der Waals density functionals applied to solids. Phys. Rev. B 83, 195131 (2011).
Dion, M. et al. Van der Waals density functional for general geometries. Phys. Rev. Lett. 92, 246401 (2004).
Dudarev, S. L. et al. Electron-energy-loss spectra and the structural stability of nickel oxide: an LSDA+U study. Phys. Rev. B 57, 1505–1509 (1998).
This work was supported by the Center for Integrated Quantum Materials under NSF grant DMR-1231319 (D.R.K., E.K. and S.F.), the DOE Office of Science, Basic Energy Sciences under award DE-SC0018935 (D.M.), as well as the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant GBMF4541 to P.J.-H.; D.R.K. acknowledges partial support by the NSF Graduate Research Fellowship Program under grant no. 1122374. R.C. acknowledges support from the Alfred P. Sloan Foundation. Q.S. is supported by the Xu Xin International Student Exchange Scholarship from Nanjing University. E.K. and S.F. are also supported by the ARO MURI award no. W911NF-14-0247. Work done at AmesLaboratory (M.X., R.A.R. and P.C.C.) was performed under contract no. DE-AC02-07CH11358. R.A.R. was supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant GBMF4411. The computations in this paper were run on the Odyssey cluster supported by the FAS Division of Science, Research Computing Group at Harvard University.
The authors declare no competing interests.
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Klein, D.R., MacNeill, D., Song, Q. et al. Enhancement of interlayer exchange in an ultrathin two-dimensional magnet. Nat. Phys. (2019) doi:10.1038/s41567-019-0651-0
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