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Title: Charge density wave transition in single-layer titanium diselenide

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 behavior of the Bardeen-Cooper-Schrieffer (BCS) gap implies a mean-field CDW order in the single layer and an anisotropic CDW order in the bulk.
Authors:
 [1] ;  [2] ;  [3] ; ORCiD logo [4] ;  [5] ; ORCiD logo [6] ;  [6] ;  [6] ;  [7]
  1. Univ. of Illinois, Urbana-Champaign, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Academia Sinica, Taipei (Taiwan)
  3. Univ. of Illinois, Urbana-Champaign, IL (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nanjing Univ. (China); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. Academia Sinica, Taipei (Taiwan); Georgia Inst. of Technology, Atlanta, GA (United States); National Taiwan Univ., Taipei (Taiwan)
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  7. Univ. of Illinois, Urbana-Champaign, IL (United States); National Taiwan Univ., Taipei (Taiwan)
Publication Date:
Grant/Contract Number:
AC03-76SF00515; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; physical sciences; condensed matter
OSTI Identifier:
1237589
Alternate Identifier(s):
OSTI ID: 1378649

Chen, P., Chan, Y. -H., Fang, X. -Y., Zhang, Y., Chou, M. Y., Mo, S. -K., Hussain, Z., Fedorov, A. -V., and Chiang, T. -C.. Charge density wave transition in single-layer titanium diselenide. United States: N. p., Web. doi:10.1038/ncomms9943.
Chen, P., Chan, Y. -H., Fang, X. -Y., Zhang, Y., Chou, M. Y., Mo, S. -K., Hussain, Z., Fedorov, A. -V., & Chiang, T. -C.. Charge density wave transition in single-layer titanium diselenide. United States. doi:10.1038/ncomms9943.
Chen, P., Chan, Y. -H., Fang, X. -Y., Zhang, Y., Chou, M. Y., Mo, S. -K., Hussain, Z., Fedorov, A. -V., and Chiang, T. -C.. 2015. "Charge density wave transition in single-layer titanium diselenide". United States. doi:10.1038/ncomms9943. https://www.osti.gov/servlets/purl/1237589.
@article{osti_1237589,
title = {Charge density wave transition in single-layer titanium diselenide},
author = {Chen, P. and Chan, Y. -H. and Fang, X. -Y. and Zhang, Y. and Chou, M. Y. and Mo, S. -K. and Hussain, Z. and Fedorov, A. -V. and Chiang, T. -C.},
abstractNote = {A single molecular layer of titanium diselenide (TiSe2) 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 TiSe2 exhibits a charge density wave (CDW) transition at critical temperature TC=232±5 K, which is higher than the bulk TC=200±5 K. Angle-resolved photoemission spectroscopy measurements reveal a small absolute bandgap at room temperature, which grows wider with decreasing temperature T below TC 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 behavior of the Bardeen-Cooper-Schrieffer (BCS) gap implies a mean-field CDW order in the single layer and an anisotropic CDW order in the bulk.},
doi = {10.1038/ncomms9943},
journal = {Nature Communications},
number = ,
volume = 6,
place = {United States},
year = {2015},
month = {11}
}

Works referenced in this record:

Generalized Gradient Approximation Made Simple
journal, October 1996
  • Perdew, John P.; Burke, Kieron; Ernzerhof, Matthias
  • Physical Review Letters, Vol. 77, Issue 18, p. 3865-3868
  • DOI: 10.1103/PhysRevLett.77.3865

Projector augmented-wave method
journal, December 1994

Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set
journal, July 1996

Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set
journal, October 1996

From ultrasoft pseudopotentials to the projector augmented-wave method
journal, January 1999