Extended Polymorphism of Two-Dimensional Material

Masaro Yoshida*, Jianting Ye, Yijin Zhang, Yasuhiko Imai, Shigeru Kimura, Akihiko Fujiwara, Terukazu Nishizaki, Norio Kobayashi, Masaki Nakano, Yoshihiro Iwasa

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)


When controlling electronic properties of bulk materials, we usually assume that the basic crystal structure is fixed. However, in two-dimensional (2D) materials, atomic structure or to functionalize their properties. Various polymorphs can exist in transition metal dichalcogenides (TMDCs) from which 2D materials are generated, and polymorphism has drastic on the electronic states. Here we report the discovery of an polymorph is attracting growing interest as a controlling parameter unprecedented polymorph of a TMDC 2D material. By mechanical exfoliation, we made thin flakes from a single crystal of 2Ha-type tantalum disulfide (TaS2), a metallic TMDC with a charge-density-wave (CDW) phase. Microbeam X-ray diffraction measurements and electrical transport measurements indicate that thin flakes possess a polymorph different from any one known in TaS2 bulk crystals. Moreover, the flakes with the unique polymorph displayed the dramatically enhanced CDW ordering temperature. The present results suggest the potential existence of diverse structural and electronic phases accessible only in 2D materials.

Original languageEnglish
Pages (from-to)5567-5571
Number of pages5
JournalNano Letters
Issue number9
Publication statusPublished - Sep-2017


  • Polymorphism
  • two-dimensional material
  • charge-density-wave (CDW)
  • electric double layer transistor (EDLT)
  • microbeam X-ray diffraction
  • MOS2
  • 2H-NBSE2
  • 4HB-TAS2
  • 1T-TAS2

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