First Principles Study On The Electronic Structure Of Two-dimensional Topological Insulators

Two dimensional topological insulator is an important branch of topological insulator.It not only has unique physical properties different from traditional insulator,but also has unique advantages compared with the three-dimensional topological insulator found in recent years.It has a significant application prospect in the manufacturing and innovation of electronic devices.Therefore,it is of great practical significance to find two-dimensional topological insulator with practical value.Many two-dimensional topological insulator materials have been predicted theoretically by using the first principles of computation.However,because most of them are difficult to be realized in practice,we still need to find the large gap topological insulator which is easier to be realized in experiments.Therefore,the main work of this paper is to obtain large gap topological insulator which can be used in practice by absorbing transition metal elements on VA group elements.We adsorbed Mo and W atoms on the blue phosphorene and applied appropriate strain.According to the calculation of HSE,the topological band gap of blue phosphorene adsorbing Mo atom is 94meV,and that of blue phosphorene adsorbing W atom is 218meV;through the adsorption of Os atom on arsenene,antimonene and bismuthene,we get the topological insulator with a band gap of about 200meV under the calculation of GGA.Because GGA usually underestimates the band gap,we reasonably speculate that this series of materials are topological insulators with reverse band gap greater than 200 meV.By analyzing the mechanism of orbital splitting,we analyzed the mechanism of topological insulation of the two-dimensional topological insulator.