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 Copy

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

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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