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Large-area high-quality 2D ultrathin Mo2C superconducting crystals

Abstract

Transition metal carbides (TMCs) are a large family of materials with many intriguing properties and applications, and high-quality 2D TMCs are essential for investigating new physics and properties in the 2D limit. However, the 2D TMCs obtained so far are chemically functionalized, defective nanosheets having maximum lateral dimensions of 10 μm. Here we report the fabrication of large-area high-quality 2D ultrathin α-Mo2C crystals by chemical vapour deposition (CVD). The crystals are a few nanometres thick, over 100 μm in size, and very stable under ambient conditions. They show 2D characteristics of superconducting transitions that are consistent with Berezinskii–Kosterlitz–Thouless behaviour and show strong anisotropy with magnetic field orientation; moreover, the superconductivity is also strongly dependent on the crystal thickness. Our versatile CVD process allows the fabrication of other high-quality 2D TMC crystals, such as ultrathin WC and TaC crystals, which further expand the large family of 2D materials.

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Figure 1: Large-area 2D ultrathin α-Mo2C crystals fabricated by CVD.
Figure 2: Characterization of 2D ultrathin α-Mo2C crystals.
Figure 3: 2D superconducting characteristics of ultrathin α-Mo2C crystals.
Figure 4: BKT transition of 2D ultrathin α-Mo2C crystals.
Figure 5: Thickness dependence of superconductivity of 2D ultrathin α-Mo2C crystals.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 51325205, 51290273, 51221264, 51172240 and 11374019), the Ministry of Science and Technology of China (No. 2012AA030303) and the Chinese Academy of Sciences (Nos. KGZD-EW-303-1 and KGZD-EW-T06).

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W.R. conceived and supervised the project, and designed the experiments; C.X. and L.C. designed and carried out growth experiments under the supervision of W.R. and H.-M.C.; Z.L. performed TEM measurements and analyses under the supervision of X.-L.M.; L.W. and J.G. carried out transport measurements under the supervision of N.K.; W.R. and N.K. analysed data and wrote the manuscript. All the authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Ning Kang or Wencai Ren.

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The authors declare no competing financial interests.

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Xu, C., Wang, L., Liu, Z. et al. Large-area high-quality 2D ultrathin Mo2C superconducting crystals. Nature Mater 14, 1135–1141 (2015). https://doi.org/10.1038/nmat4374

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