Superconductivity and hybrid soft modes in
- Karlsruhe Institute of Technology, Karlsruhe (Germany)
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Drexel Univ., Philadelphia, PA (United States)
- Univ. of Amsterdam, Amsterdam (The Netherlands)
The interplay between superconductivity and charge-density-wave (CDW) order plays a central role in the layered transition-metal dichalcogenides. 1T-TiSe2 forms a prime example, featuring superconducting domes on intercalation as well as under applied pressure. Here, we present high energy-resolution inelastic x-ray scattering measurements of the CDW soft phonon mode in intercalated CuxTiSe2 and pressurized 1T-TiSe2 along with detailed ab-initio calculations for the lattice dynamical properties and phonon-mediated superconductivity. We find that the intercalation-induced superconductivity can be explained by a solely phonon-mediated pairing mechanism, while this is not possible for the superconducting phase under pressure. We argue that a hybridization of phonon and exciton modes in the pairing mechanism is necessary to explain the full observed temperature-pressure-intercalation phase diagram. Finally, these results indicate that 1T-TiSe2 under pressure is close to the elusive state of the excitonic insulator.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- Materials Sciences and Engineering Division; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1352569
- Alternate ID(s):
- OSTI ID: 1335193
- Journal Information:
- Physical Review B, Vol. 94, Issue 21; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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