Charge density wave transition in single-layer titanium diselenide
- Univ. of Illinois, Urbana-Champaign, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Academia Sinica, Taipei (Taiwan)
- Univ. of Illinois, Urbana-Champaign, IL (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nanjing Univ. (China); SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Academia Sinica, Taipei (Taiwan); Georgia Inst. of Technology, Atlanta, GA (United States); National Taiwan Univ., Taipei (Taiwan)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Univ. of Illinois, Urbana-Champaign, IL (United States); National Taiwan Univ., Taipei (Taiwan)
© 2015 Macmillan Publishers Limited. All rights reserved. A single molecular layer of titanium diselenide (TiSe 2 ) is a promising material for advanced electronics beyond graphene - a strong focus of current research. Such molecular layers are at the quantum limit of device miniaturization and can show enhanced electronic effects not realizable in thick films. We show that single-layer TiSe 2 exhibits a charge density wave (CDW) transition at critical temperature T C =232±5 K, which is higher than the bulk T C =200±5 K. Angle-resolved photoemission spectroscopy measurements reveal a small absolute bandgap at room temperature, which grows wider with decreasing temperature T below T C in conjunction with the emergence of (2 × 2) ordering. The results are rationalized in terms of first-principles calculations, symmetry breaking and phonon entropy effects. The observed Bardeen-Cooper-Schrieffer (BCS) behaviour of the gap implies a mean-field CDW order in the single layer and an anisotropic CDW order in the bulk.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC03-76SF00515; AC02-05CH11231
- OSTI ID:
- 1237589
- Alternate ID(s):
- OSTI ID: 1378649
- Journal Information:
- Nature Communications, Vol. 6; ISSN 2041-1723
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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