Superconductivity in the metastable 1T and 1T phases of MoS2 crystals

C. Shang, Y. Q. Fang, Q. Zhang, N. Z. Wang, Y. F. Wang, Z. Liu, B. Lei, F. B. Meng, L. K. Ma, T. Wu, Z. F. Wang, C. G. Zeng, F. Q. Huang, Z. Sun, and X. H. Chen
Phys. Rev. B 98, 184513 – Published 21 November 2018

Abstract

Transition-metal dichalcogenides open novel opportunities for the exploration of exciting new physics and devices. As a representative system, 2H-MoS2 has been extensively investigated owing to its unique band structure with a large band gap, degenerate valleys, and nonzero Berry curvature. However, experimental studies of metastable 1T polytypes have been a challenge for a long time, and electronic properties are obscure due to the inaccessibility of single phase without the coexistence of 1T, 1T, and 1T lattice structures, which hinder the broad applications of MoS2 in future nanodevices and optoelectronic devices. Using Kx(H2O)yMoS2 as the precursor, we have successfully obtained high-quality layered crystals of the metastable 1T-MoS2 with 3a×3a superstructure and metastable 1T-MoS2 with a×2a superstructure, as evidenced by structural characterizations through scanning tunneling microscopy, Raman spectroscopy, and x-ray diffraction. It is found that the metastable 1T-MoS2 is a superconductor with onset transition temperature (Tc) of 4.2 K, while the metastable 1T-MoS2 shows either superconductivity with Tc of 5.3 K or insulating behavior, which strongly depends on the synthesis procedure. Both of the metastable polytypes of MoS2 crystals can be transformed to the stable 2H phase with mild annealing at about 70 °C in He atmosphere. These findings provide pivotal information on the atomic configurations and physical properties of 1T polytypes of MoS2.

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  • Received 3 September 2018
  • Revised 21 October 2018

DOI:https://doi.org/10.1103/PhysRevB.98.184513

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

C. Shang1, Y. Q. Fang2,3, Q. Zhang1, N. Z. Wang1, Y. F. Wang1, Z. Liu1, B. Lei1, F. B. Meng1, L. K. Ma1, T. Wu1,4,5,6, Z. F. Wang1, C. G. Zeng1,7, F. Q. Huang2,3,4, Z. Sun1,6,8,*, and X. H. Chen1,4,5,6,†

  • 1Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Hefei National Laboratory for Physical Sciences at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
  • 2State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
  • 3State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Peking 100871, China
  • 4CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, China
  • 5CAS Center for Excellence in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China
  • 6Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
  • 7Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
  • 8National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China

  • *Corresponding author: zsun@ustc.edu.cn
  • Corresponding author: chenxh@ustc.edu.cn

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Issue

Vol. 98, Iss. 18 — 1 November 2018

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