Dear all,
Can somebody please put some light on how the position of band inversion, near or away the Fermi level affects the electrical transport and thermal properties in semi-metals?
Thanks in advance!
Dear Dr. P. Contreras Many thanks for sharing the above answer. Please suggest its relation to thermal properties too.
and band inversion is:- some of the orbitals of the valence band get contribution in the conduction band and vice versa. Please find the attached figure for your reference.
Thanks a lot for your kind response.
Dear Dr. P. Contreras Let me explain the band inversion by taking a general example.
suppose we have an insulator, which has a finite gap between the ground
state and all excited states. According to the principle of adiabatic continuity, a system will always remain in the ground state as a function of smooth deformation. Based on this, two insulators are topological equivalent, if they can be smoothly deformed into each other without closing the gap. Once the gap closes at the quantum critical point, the energy states get reversed, and in terms of band picture, we can say band inversion takes place. It is mainly the topological effect and occurs due to the presence of Spin-orbit coupling in Quantum spin-hall systems, also knowns as Topological insulators. PFA image for more clarification.
Please let me know if I am not able to make it clear.
Thanks a lot!
I found this discussion really informative and thought provoking. To understand the effect of band-inversion on thermal properties, you can calculate the phonon dispersion and heat capacities choosing s standard topological semimetal and insulator by computational or experimental methods. Comparing the results with DOS and band-structure, you'll be able to analyze the effect of separation-gap from the Fermi level on thermal properties. Temperature-dependence of phonon mean free path and various phonon scatterings can also lead to interesting results. As this topic really deals with core condensed matter physics, without proper data any comment might lead to rather crude elaborations.
On the other hand, electrical transport is a bit more trivial. In most materials, as the difference from Fermi level increases, transport weakens. However for semimetals, as there is some non-zero DOS near Fermi level, the property will be different a bit and highly depend on the DOS. These are interesting topics for further research.
Dear Dr. P. Contreras Many thanks for your constant replies to this thread, and yes, these are quantum spin hall insulators, and adiabatic deformation is just one way to understand the same. These things are clear to me, my concern is just to understand the effect of its position from the Fermi level on the electrical and thermal properties, in which electrical one is now clear to me. I am now a little worried about the thermal one.
Thanks a lot for the above links, and your efforts to make the things clear.
With Regards,
Payal
Dear Dr. P. Contreras , Many thanks for such a great effort and being very kind. and yes sir, green's function formalism has also been developed to describe the surface state like properties.
Thanks a lot!!
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