Alexandria Digital Research Library

Exotic, topological, and many body localized quantum phase transitions

Author:
Slagle, Kevin Jacob
Degree Supervisor:
Cenke Xu
Place of Publication:
[Santa Barbara, Calif.]
Publisher:
University of California, Santa Barbara
Creation Date:
2016
Issued Date:
2016
Topics:
Condensed matter physics
Keywords:
Exotic
Symmetry protected
Many body localization
Topological order
Spin liquid
Quantum phase transition
Genres:
Online resources and Dissertations, Academic
Degree Grantor:
University of California, Santa Barbara. Physics
Dissertation:
Ph.D.--University of California, Santa Barbara, 2016
Description:

In this thesis we will study recent examples of exotic, topological, and many body localized quantum phase transitions. In Chapter 2 we study the quantum phase transition between the Z2 spin liquid and valence bond solid (VBS) orders on a triangular lattice. We find a possible nematic Z2 spin liquid intermediate phase and predict a continuous 3d XY* transition to the neighboring columnar and resonating-plaquette VBS phases. In Chapter 3 we demonstrate that an extended Kane-Mele Hubbard model on a bilayer honeycomb lattice has two novel quantum phase transitions. The first is a quantum phase transition between the weakly interacting gapless Dirac fermion phase and a strongly interacting fully gapped and symmetric trivial phase, which cannot be described by the standard Gross-Neveu model. The second is a quantum critical point between a quantum spin Hall insulator with spin Sz conservation and the previously mentioned strongly interacting fully gapped phase. We argue that the first quantum phase transition is related to the Z16 classification of the topological superconductor 3He-B phase with interactions, while the second quantum phase transition is a topological phase transition described by a bosonic O(4) nonlinear sigma model field theory with a Theta-term. In Chapter 4 we propose that if the highest and lowest energy eigenstates of a Hamiltonian belong to different SPT phases, then this Hamiltonian can't be fully many body localized. In Chapter 5 we study the disordered XYZ spin chain and its marginally many body localized critical lines, which we find to be characterized by an effective central charge c'=ln2 and continuously varying critical exponents.

Physical Description:
1 online resource (133 pages)
Format:
Text
Collection(s):
UCSB electronic theses and dissertations
ARK:
ark:/48907/f37m081x
ISBN:
9781369146745
Catalog System Number:
990046969110203776
Rights:
Inc.icon only.dark In Copyright
Copyright Holder:
Kevin Slagle
File Description
Access: Public access
Slagle_ucsb_0035D_13021.pdf pdf (Portable Document Format)