Numerical study of excitonic orders in strongly correlated systems
Abstract/Contents
- Abstract
- Harnessing unconventional phases of matter in strongly-correlated electron systems holds great promise for the functionalization of quantum properties of materials. Soon after the prediction of Bose-Einstein condensation, it was realized that the concept of condensation can be generalized to arbitrary systems of bosonic quasiparticles, including excitons -- bound pairs of electrons and holes. Understanding the emergence of excitonic instabilities from strong electronic interactions has remained challenging for numerical methods, including determinant quantum Monte Carlo (DQMC), due to the notorious sign problem. In this thesis, I present sign-free DQMC studies of excitonic orders in multi-band Hubbard-like models. First, I show results for a bilayer Hubbard model with equal and opposite electron-hole doping in the two layers, which is proposed to be an ideal platform to study excitonic orders due to suppressed recombination of inter-layer electrons and holes. Here, our study demonstrates convincing evidence for the existence of the bi-excitonic condensation phase in the vicinity of the high-symmetric point at finite electron-hole doping, as well as a competing (pi, pi) charge density wave (CDW) state. Furthermore, we analytically investigate the strong coupling limit of the model, providing physical insight underlying the emergence of the bi-excitonic condensation phase. Second, I discuss a half-filled two-orbital Hubbard-Kanamori model with broken orbital degeneracy, which accounts for the role of Hund's coupling in transition-metal compounds and other materials of multi-orbital nature. For strong inverted (negative) Hund's coupling, we find numerical evidence for the emergence of a Z2 symmetry breaking excitonic density order, which competes with an anti-ferro-orbital (AFO) order as a function of orbital splitting and Hund's coupling.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2022; ©2022 |
| Publication date | 2022; 2022 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Huang, Xuxin |
|---|---|
| Degree supervisor | Devereaux, Thomas Peter, 1964- |
| Degree supervisor | Heinz, Tony F |
| Thesis advisor | Devereaux, Thomas Peter, 1964- |
| Thesis advisor | Heinz, Tony F |
| Thesis advisor | Kivelson, Steven |
| Degree committee member | Kivelson, Steven |
| Associated with | Stanford University, Department of Applied Physics |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Xu-Xin Huang. |
|---|---|
| Note | Submitted to the Department of Applied Physics. |
| Thesis | Thesis Ph.D. Stanford University 2022. |
| Location | https://purl.stanford.edu/bh435zn8216 |
Access conditions
- Copyright
- © 2022 by Xuxin Huang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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