Abstract
It is now well established that many of the technologically important properties of two-dimensional (2D) materials, such as the extremely high carrier mobility in graphene1 and the large direct band gaps in MoS2 monolayers2, arise from quantum confinement. However, the influence of reduced dimensions on electron–phonon (e–ph) coupling and its attendant dephasing effects in such systems has remained unclear. Although phonon confinement3,4,5,6,7 is expected to produce a suppression of e–ph interactions in 2D systems with rigid boundary conditions6,7, experimental verification of this has remained elusive8. Here, we show that the e–ph interaction is, indeed, modified by a phonon dimensionality crossover in layered Nb3SiTe6 atomic crystals. When the thickness of the Nb3SiTe6 crystals is reduced below a few unit cells, we observe an unexpected enhancement of the weak-antilocalization signature in magnetotransport. This finding strongly supports the theoretically predicted suppression of e–ph interactions caused by quantum confinement of phonons.
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Acknowledgements
The authors are grateful to J. DiTusa for informative discussions. The work at Tulane is supported by the US National Science Foundation under grant DMR-1205469 and the NSF EPSCoR Cooperative Agreement No. EPS-1003897, with additional support from the Louisiana Board of Regents. P.W.A. and T.J.L. acknowledge the support of the US Department of Energy, Office of Science, Basic Energy Sciences, under Award No.DE-FG02-07ER46420. L.Y.A. and P.B.S. acknowledge the support of the Russian Science Foundation (project #14-12-01217) and are grateful to the Joint Supercomputer Center of the Russian Academy of Sciences and ‘Lomonosov’ Research Computing Center for the opportunity of using a cluster computer for the quantum-chemical calculations. P.B.S. acknowledges a Grant of the President of the Russian Federation for government support of young PhD scientists MK-6218.2015.2 (project ID 14.Z56.15.6218-MK). Z.I.P. acknowledges the support of the Leading Science School program (No NSh-2886.2014.2). D.N. and H.J. acknowledge support through the US Department of Energy, Office of Science, Basic Energy Sciences award DE-FG02-06ER46337. The work at UNO is supported by the US National Science Foundation under the NSF EPSCoR Cooperative Agreement No. EPS-1003897, with additional support from the Louisiana Board of Regents.
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J.H., J.Y.L., H.W.Z. and Z.Q.M. carried out bulk sample growth and characterization, including XRD, resistivity and specific heat measurements. J.H., X.L., C.L.Y. and J.W. fabricated the nano-devices. J.H., X.L., T.J.L., P.W.A., S.M.A.R., and L.S. collected resistivity and magnetotransport data for the nano-devices. J.H. and J.B.H. carried out TEM measurements. H.J. and D.N. performed Raman spectrum measurements. L.Y.A., Z.I.P. and P.B.S. calculated the electronic structure. J.H., J.W., Z.Q.M., P.W.A., D.N. and P.B.S. analysed the data and wrote the manuscript. J.H. and X.L. contributed equally to this work. This project was supervised by Z.Q.M. and J.W.
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Hu, J., Liu, X., Yue, C. et al. Enhanced electron coherence in atomically thin Nb3SiTe6. Nature Phys 11, 471–476 (2015). https://doi.org/10.1038/nphys3321
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DOI: https://doi.org/10.1038/nphys3321
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