All Questions
10
questions
0
votes
2
answers
111
views
What is the physical meaning of adiabatically varying the wavevector $k$ as a parameter to calculate the Chern number for topological effects?
Could it mean something like applying a weak electric field and perturbing the band structure? Or some other weak perturbation? Or is that the wrong idea?
- 107
1
vote
1
answer
910
views
What is a bulk state and bulk bands?
I am a bachelor student and I started studying topology and I came across two terms I have never seen before: Bulk band structure and bulk states.
Can someone explain these two terms or provide me a ...
- 155
2
votes
0
answers
79
views
Topology of Helium 3A and 3B
The question concerns the topology and dimensions of Helium 3A and 3B
A. The Helium 3A phase shows the same low energy excitations as those of a 2 spatial dimensional chiral p-wave superconductor --- ...
- 4,336
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
6
votes
1
answer
387
views
Is topological surface state always tangential to bulk bands?
Think of a topologically nontrivial $D$-dimensional system. Its bulk bands form a $D+1$-dimensional manifold ($+1$ from energy). Its surface/edge bands form a $D$-dimensional one. Is the latter always ...
- 3,701
0
votes
1
answer
424
views
Winding number of SSH model 3
SSH model can be written as
$$H=-\sum_n\big[Jc_n^\dagger d_n + J'd_n^\dagger c_{n+1}\big]+h.c.$$
in Fourier space
$$H(k)=
\begin{bmatrix}
c_k^\dagger && d_{k}^\dagger
\end{bmatrix}
\begin{...
- 1,335
2
votes
1
answer
228
views
Units related to chemical potential and orbital magnetization
I am studying this paper: Physical Review B 74, 024408 (2006) (arxiv)
Abstract
We derive a multi-band formulation of the orbital magnetization in a normal periodic insulator (i.e., one in which the ...
- 486
0
votes
2
answers
868
views
Chern number for the systems with open boundary conditions
For two-dimensional materials with periodic boundary conditions, we can solve the Bloch states and substitute them into the definition of Chern number, as shown in the picture:
In the case of open ...
9
votes
1
answer
559
views
AKLT state and Nobel physics prize 2016
The AKLT Hamiltonian and the chain is described in Wikipedia, and also the page 17 of this year Nobel Prize advanced information
I have questions concerning the info released by nobelprize.org, and ...
user32229
2
votes
2
answers
420
views
What can we learn from a band structure diagram?
Other than the band gap and its magnitude, what are the things that we can immediately learn about the properties of the material just by glancing at its band structure?
Can we say something about ...
- 366