On the Nature of Charge Density Waves, Superconductivity and Their Interplay in 1T-TiSe₂

1. Front Matter

   Pages i-xvi

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2. Introduction

   • Chuan Chen

   Pages 1-14

3. Excitonic Character of CDW in TiSe2

   • Chuan Chen

   Pages 15-29

4. Phenomenological Model of Coexisting CDW and Superconductivity in TiSe2

   • Chuan Chen

   Pages 31-49

5. Excitonic CDW Fluctuations and Superconductivity

   • Chuan Chen

   Pages 51-67

6. Anomalous Quantum Metal Phase in TiSe2

   • Chuan Chen

   Pages 69-81

7. Conclusions

   • Chuan Chen

   Pages 83-85

8. Back Matter

   Pages 87-105

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This thesis presents analytical theoretical studies on the interplay between charge density waves (CDW) and superconductivity (SC) in the actively studied transition-metal dichalcogenide 1T-TiSe2. It begins by reapproaching a years-long debate over the nature of the phase transition to the  commensurate CDW (CCDW) state and the role played by the intrinsic tendency towards excitonic condensation in this system.  A Ginzburg-Landau phenomenological theory was subsequently developed to understand the experimentally observed transition from commensurate to incommensurate CDW (ICDW) order with doping or pressure, and the emergence of a superconducting dome that coexists with ICDW. Finally, to characterize microscopically the effects of the interplay between CDW and SC, the spectrum of CDW fluctuations beyond mean-field was studied in detail. In the aggregate, the work reported here provides an encompassing understanding of what are possibly key microscopic underpinnings of the CDWand SC physics in TiSe2.   

• Charge Density Waves
• Superconductivity and charge density waves
• TiSe2
• Transition Metal Dichalcognides
• Discommensuration
• Ginzburg-Landau theory
• CDW Fluctuations
• Excitonic condensation

• Center for Advanced 2D Materials, National University of Singapore, Singapore, Singapore

  Chuan Chen

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