In partial fulfillment of the requirements for the degree of 

Doctor of Philosophy in Physics 

School of Physics Thesis Dissertation Defense

Fatemeh Borhani

Dr. Itamar Kimchi, School of Physics, Georgia Institute of Technology (Advisor)

Emergence of Chirality from Crystalline Defects in Kitaev Spin Liquids

Date: Friday, March 6, 2026

Time: 8:30 a.m.

Location: Howey N110 

Committee members:

Dr. Dragomir Davidovic, School of Physics, Georgia Institute of Technology

Dr. Martin Mourigal, School of Physics, Georgia Institute of Technology

Dr. Zhigang Zhang, School of Physics, Georgia Institute of Technology

Dr. Joshua Kretchmer, School of Chemistry and Biochemistry, Georgia Institute of Technology

Abstract:

We study the spin-1/2 Kitaev honeycomb gapless spin liquid in the presence of various defects that create odd-sided plaquettes, including topological dislocations and Stone-Wales–type local lattice defects. These defects induce local chirality and orbital magnetization. While the clean Kitaev model exhibits no finite-temperature phase transitions, a finite defect density leads to a genuine phase transition, with a transition temperature that scales with the defect density. This disorder-driven instability arises from an emergent long-range ferromagnetic interaction, r^γ (γ≈2.7), between defect-induced chiralities, mediated by the nearly gapless Majorana fermions.