Questions tagged [topological-insulators]

For questions about modeling topological insulators (materials which are insulating in the bulk, but have conductive surface states due to specific topology of their band structure).

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5
votes
0answers
49 views

Calculating the Chern number on a 2D surface of a 3D insulator

I want to calculate the Chern number of a surface of 3D time reversal insulator. I know the 3D topological insulator was characterised by the Z2 index. And the Chern number was used characterised the ...
10
votes
2answers
101 views

About the surface Greens function method for calculating the surface state

Currently I'm using some software package to do the data analysis from the DFT calculation so that I can study the surface state of some topological insulator. I found that the method they use is ...
8
votes
1answer
91 views

Topological order in Weyl Semimetal

Is the topological phase in a Weyl semimetal is intrinsic or symmetry protected? How can we realize that? If symmetry protected, which symmetry protects the topological phase of non-centrosymmetric ...
9
votes
1answer
165 views

Can the fermi level of a semiconductor be below the valence band?

I was looking at the data on this page for a NiWO4 calculation. I can see unoccupied bands near the fermi level that appear to be below the band gap. What does this actually mean physically or is it ...
12
votes
2answers
277 views

What is the difference between Ultrasoft, ONCV and PAW Pseudopotentials? Which is better for a spin-orbit coupled calculation?

I am trying to do spin-orbit coupled calculations for various topological insulators. I have found papers using Quantum Espresso with ONCV pseudopotentials and papers using VASP with PAW ...
9
votes
0answers
75 views

Is the non-trivial band topology in a system, caused by spin-orbit-coupling or band inversion?

How can we know that the non-trivial band topology in a system is driven by spin-orbit coupling (SOC) or by band inversion? Based on my understanding, SOC causes the band inversion and makes the ...
11
votes
1answer
62 views

Edge states in Topological Semimetals

Does it make any sense to calculate edge states for topological semimetals while they don't have any global gap?
15
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3answers
1k views

Magnetism and Topology

Can magnetism and topological insulating behavior coexist in a material? If yes, can someone refer to a recent work?
10
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3answers
136 views

How to model Topological Insulators from first-principles?

Topological insulators and quantum materials are gaining increasing interest across the physical, chemical and materials communities. Today, one can go to the Topological Materials Database and see ...
25
votes
1answer
793 views

What is band inversion and how to recognize it in band structure?

Band inversion is a key ingredient of a topologically nontrivial material$^1$. What is band inversion? How to recognize it in a band structure? What conclusions can I infer if I observe band inversion ...
16
votes
1answer
59 views

What are good resources to study crystallographic defects in different dimensional systems and their topological dimensionality?

I wonder if there are any books or resources that may address one or more of the following questions: What kinds of defects are important for topology? Especially crystallographic defects. How do ...
17
votes
1answer
99 views

What exactly is a topological insulator and how to recognize one from band structure?

Four years ago, the Nobel Prize in physics was awarded for "for theoretical discoveries of topological phase transitions and topological phases of matter." In line with this, I heard of topological ...