All Questions
9
questions
3
votes
0
answers
78
views
Zero frequency limit of Hall conductivity not quantized?
The transverse conductivity $\sigma_{xy}$ at zero frequency is quantized when the chemical potential $\mu$ is within the gap for a topological system, such as quantum Hall effect and Haldane model. ...
- 3,701
4
votes
0
answers
110
views
Does Hall conductivity change sign with chemical potential?
The transverse conductivity $\sigma_{xy}$ at zero frequency is quantized when the chemical potential $\mu$ is within the gap for a topological system. A typical plot of $\sigma_{xy}(\mu)$ is like the ...
- 3,701
1
vote
0
answers
99
views
The flat-band basis, Green's function projectors, and TKNN
Bernevig & Hughes' book "Topological Insulators and Topological Superconductors" have a derivation of the TKNN invariant in terms of the finite-temperature Green's function. From the ...
1
vote
0
answers
70
views
Is Hall conductivity time-reversal-odd at finite frequency in a topological system?
In some topological materials, e.g., the quantum (anomalous) Hall state and some related variants, the Hall conductivity $\sigma_{xy}$ is quantized and directly related to the Chern number, which ...
- 3,701
5
votes
1
answer
484
views
Difference between "ordinary" quantum Hall effect and quantum anomalous Hall effect
I am reading a review article on Weyl semimetal by Burkov where he writes, top of page 5:
A 3D quantum anomalous Hall insulator may be obtained by making a stack of 2D quantum Hall insulators [Ref. ...
- 508
2
votes
0
answers
107
views
How does Laughlin argument for hierarchical fractional quantum Hall effect work?
For 1 level and 1 layer $1/q$ FQHE let's say $q=5$ we have the following argument for Laughlin gauge principle. It says that if we adiabatically increase the flux from $0$ to $q\phi_0$ of a corbino ...
- 1,369
1
vote
1
answer
1k
views
How to calculate Edge states of Topological insulators
Topological insulators are novel state of matter in which bulk is insulator and edges are gapless. How do we calculate these gapless states? I am reading the following PRL
Feng Liu and Katsunori ...
- 831
2
votes
1
answer
2k
views
Why is disorder essential for the Integer Quantum Hall effect IQHE?
The title already gives away the question. I see that disorder effects that the Landau levels are broadened out. They allow states to be either extended through the whole solid or localized to a ...
- 808
3
votes
0
answers
911
views
Simple model of edge states for a two-dimensional topological insulator
Quantum spin Hall states or, topological insulators are novel states of matter that have insulating bulk and gapless edge states. Are there any simple models that show these features?
See e.g. the ...
