Theoretical Study On Physical Properties Of Two-dimensional Topological Insulators

The bulk states of topological insulators are insulating,while the edge states(or surface states)are spin resolved and across the Fermi level in the band gap.Hence,due to the unique electronic properties and wide application prospects in superconducting,spin electronic devices and quantum computation etc,the topological insulators become one of the most attractive research topics in condensed matter physics.At present,scientists predicted many topological insulators theoretically,but few of them can be actually fabricated.Since it is extremely hard to synthesize the free-standing two dimensional topological insulators,they need to be grown on a substrate and then the proximity effect of the substrate must be taken into account.In this dissertation,ab initio calculation and tight-binding method were carried out to study the structural,electronic and topological properties of two kinds of two-dimensional topological insulator Hg Te and IIIV(Ga Bi,In Bi,Tl Bi,Tl As and Tl Sb)monolayer on the(0001)surface of ?-Al2O3.We found that the structures of Hg Te and IIIV monolayers are well supported by ?-Al2O3 and the topological properties are preserved.Our works pave a way for the realization and application of the quantum spin Hall state.