University of Illinois Urbana-Champaign

Emergence of charge density wave domain walls above the superconducting dome in TiSe2

Joe, Young Il

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https://hdl.handle.net/2142/49590

Description

Title
Emergence of charge density wave domain walls above the superconducting dome in TiSe2
Author(s)
Joe, Young Il
Issue Date
2014-05-30T16:51:23Z
Director of Research (if dissertation) or Advisor (if thesis)
Abbamonte, Peter M.
Doctoral Committee Chair(s)
Chiang, Tai-Chang
Committee Member(s)
  • Phillips, Philip W.
  • Grosse Perdekamp, Matthias
  • Abbamonte, Peter M.
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2014-05-30T16:51:23Z
Keyword(s)
  • charge density wave
  • incommensurate charge density wave
  • domain wall
  • X-ray diffraction
  • transition metal dichacogenide
  • superconductivity
  • high pressure
  • low temperature
Abstract
Superconductivity (SC) in so-called “unconventional superconductors” is nearly always found in the vicinity of another ordered state, such as antiferromagnetism, charge density wave (CDW), or stripe order. This suggests a fundamental connection between SC and fluctuations in some other order parameter. 1T-TiSe2 is a prototypical CDW material in the transtion-metal dichalcogenide family and was previously shown to exhibit SC when the CDW is suppressed by hydrostatic pressure or intercalation of Cu atoms. Here, we present detailed high pressure x-ray scattering study on 1T-TiSe2. We found that the CDW phase of 1T-TiSe2 is completely suppressed on the application of hydrostatic pressure and established the existence of a quantum critical point (QCP) at $P_c = 5.1 +- 0.2 GPa, which is more than 1 GPa beyond the end of the SC region. Unexpectedly, at P = 3 GPa we observed a weakly first order, incommensurate CDW phase, suggesting the presence of a Lifshitz tricritical point somewhere above the superconducting dome. Our study suggests that SC in 1T-TiSe2 may not be directly connected to the QCP of the CDW order, but to the formation of CDW domain walls.
Graduation Semester
2014-05
Permalink
http://hdl.handle.net/2142/49590
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Copyright 2014 Young Il Joe

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