Seminarium "Teoria i Modelowanie Nanostruktur"

Topological insulators (TIs) are a new class of quantum matter withinsulating bulks and conducting edge/surface states which are protected bythe time-reversal symmetry. Topological Crystalline insulators (TCIs) havesimilar features like TIs, though crystal symmetries protect these states.It will be shown that thick films of (Pb,Sn)Te and (Pb,Sn)Se, for highenough content of Sn when the band gap is inverted, are TCIs whose helicalDirac-like surface states are protected by mirror symmetries.However, (111)-oriented ultrathin films of such materials exhibit quantumspin Hall phase (or 2D TI), which is due to the intersection of thevalence and conduction bands within particular thicknesses. Suchpredictions will be demonstrated and endorsed by electric band structuresand edge spectral function calculation