Mathematical theory for topological insulators

In summary: You can go through the Laughlin variational wave function, the Haldane hierarchy, the composite fermion, the moore read pfaffian, and the MR pfaffian for the half filled case. There are great reviews by Jain, Willett, and Wen.
  • #1
taishizhiqiu
63
4
I have been learning topological insulators recently, and I become more and more curious about the link between topological insulators and mathematical theory these days.

I know topological insulators have something to do with fiber bundles and K-theory. I have a relatively good background of undergraduate topology and recently I have read some introduction about fiber bundles and K-theory. What is missing in my mind is the link between math and physics. That is, what exactly do we regard as fiber bundles and classify them as trivial and non-trivial?

Can someone kindly give me the answer or some references?
 
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  • #2
Look at the books by Fradkin, Bernevig/Hughes, and Wen.

When you talk about TIs or the IQHE/FQHE, the nontrivial topology is in the Bloch wave function. You are looking at the Berry phase of this wave function and the fact that the wf must be single valued gives you some quantization condition. For the QHE you get the chern number, for TIs you get a Z2 invariant. If the system is topologically nontrivial, you cannot define a wf that is valid globally. This is the same idea as the Dirac monopole or Aharanov Bohm effect
 
  • #3
radium said:
Look at the books by Fradkin, Bernevig/Hughes, and Wen.

When you talk about TIs or the IQHE/FQHE, the nontrivial topology is in the Bloch wave function. You are looking at the Berry phase of this wave function and the fact that the wf must be single valued gives you some quantization condition. For the QHE you get the chern number, for TIs you get a Z2 invariant. If the system is topologically nontrivial, you cannot define a wf that is valid globally. This is the same idea as the Dirac monopole or Aharanov Bohm effect
Can you give me names of the books? I can't find them on google.
 
  • #4
Field theories of condensed matter, topological insulators and topological superconductors, and quantum field theory of many body systems: from the origin of sound to an origin of light and electrons. The first two have chapters explicitly on Z2 TIs and TSCs. The second has a chapter or two on the IQHE and FQHE and a chapter about topology in condensed matter. It does not explicitly discuss Z2 TIs but does discuss things you should know about them.

In general, the best way to learn about these states is to start from the integer QHE, then go to the Haldane model for graphene, then go to the KM model in graphene (it is good to read that paper and a few of the ones after that) then go to 3D TIs/FKM model. Then you can learn about TSCs (the mapping from the quantum ising model to the majorana chain is very important).

If you want to learn about the FQHE, I would save that for last, it is incredibly subtle.
 

FAQ: Mathematical theory for topological insulators

What is a topological insulator?

A topological insulator is a material that behaves as an insulator in its interior, but has conducting properties on its surface or edges. This is due to its unique electronic band structure, which is protected by topology and not affected by small changes in the material's properties.

What is the mathematical theory behind topological insulators?

The mathematical theory for topological insulators is based on topology, a branch of mathematics that studies the properties of geometric objects that are preserved under continuous deformations. In topological insulators, the electronic band structure is described using topological invariants, such as the Chern number and the Z2 index, which are calculated using mathematical techniques such as Berry curvature and K-theory.

How are topological insulators different from conventional insulators?

Unlike conventional insulators, which are defined by their large band gap between the valence and conduction bands, topological insulators have a non-trivial band gap and exhibit conducting properties on their surface. This is due to their unique electronic band structure, which is protected by topology and not affected by impurities or defects in the material.

What are the potential applications of topological insulators?

Topological insulators have potential applications in fields such as spintronics, quantum computing, and energy harvesting. Their unique electronic properties, such as the spin-momentum locking effect, allow for efficient manipulation and control of electron spin, which is important for these technologies. They also have potential applications in creating low-power and high-speed electronic devices.

How are topological insulators experimentally characterized?

Topological insulators can be experimentally characterized using various techniques, such as angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), and transport measurements. These techniques can provide information about the electronic band structure and topological invariants, which can confirm the presence of topological surface states in the material. Other techniques, such as Raman spectroscopy and X-ray diffraction, can also provide valuable information about the crystal structure and properties of topological insulators.

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