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Title: Emergence of coherence in the charge-density wave state of 2H-NbSe2

A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature Tcdw. Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2H-NbSe2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on the electronic dispersion, giving rise to an energy gap. The phase transition at Tcdw marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. As a result, our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in ‘pseudogap’ states.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [7] ;  [8] ;  [4] ;  [9] ;  [10] ;  [7] ;  [11] ;  [11] ;  [7] ;  [7]
  1. Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Virginia, Charlottesville, VA (United States)
  2. Univ. of Virginia, Charlottesville, VA (United States); Univ. of Illinois, Chicago, IL (United States)
  3. Temple Univ., Philadelphia, PA (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States); Karlsruhe Inst. of Technology (Germany)
  5. Drexel Univ., Philadelphia, PA (United States)
  6. Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
  7. Argonne National Lab. (ANL), Argonne, IL (United States)
  8. Argonne National Lab. (ANL), Argonne, IL (United States); Cornell Univ., Ithaca, NY (United States)
  9. Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Amsterdam (Netherlands)
  10. Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Illinois, Chicago, IL (United States)
  11. The Ohio State Univ., Columbus, OH (United States)
Publication Date:
OSTI Identifier:
1210744
Grant/Contract Number:
SC0012575; SC0005035; FG02-07ER46423; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Related Information: CCDM partners with Temple University (lead); Brookhaven National Laboratory; Drexel University; Duke University; North Carolina State University; Northeastern University; Princeton University; Rice University; University of Pennsylvania; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Univ. of Texas, Austin, TX (United States); Argonne National Laboratory (ANL), Argonne, IL (United States
Sponsoring Org:
USDOE SC Office of Basic Energy Sciences (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE catalysis (heterogeneous); solar (photovoltaic); energy storage (including batteries and capacitors); hydrogen and fuel cells; defects; mechanical behavior; materials and chemistry by design; synthesis (novel materials)