Superconductivity In Electron-Doped Arsenene

Compared to normal materials,two dimensional materials possess many unique properties and have been attracted more attention.Researches on low dimensional materials plays great role on the understanding of superconduc-tivity.The first maded two dimensional material is graphene which generated mountains of studies on layered materials.Latterly,the silicene and ger-manene which belong to the same family of graphene have been produced and studied.Borophene demonstrated lots of different structures since the electron deficiency property.Therefore borophene has different types depends on the coordination number.Phosphorene has been widely focused because the excellent carrier mobility and proper band gap.As the same family of VA,arsenene is more stable compared to the phosphorene,which can be exist stably in laboratories.Meanwhile,arsenene demonstrates a better band gap compared to graphene.In these reasons,the research on arsenene can make a good impact on the understanding of 2D materials properties and guideline on 2D materials application.On the other hand,induced superconductivity in 2D materials is the tar-get which people have been looking for.The BCS theory is the most mature theory that people have been discovered.The basic idea of BCS theory is making two electrons which possess the opposite momentum and spin to form the so called‘Cooper pair'.Based upon this theory,the density of states at Fermi surface and electron-phonon coupling is two important factors af-fect materials'superconductivity.Since the carrier concentration and stress will change these two factors,finding ways to change carrier concentration and stress are main thoughts to adjust materials'superconductivity.In actu-al materials preparation,the substrate plays important roles such as charge transition and interaction on the prepared materials.The roles which sub-strates play on have the same effects as mentioned above.Based upon these methods,Li intercalated graphene is observed superconductivity of transition temperature at 7.1 K experimentally.While the borophene has the transition temperature as high as 24.7 K on hole doped and stress conditions.How-ever,It hasn't been observed since the interaction between borophene and substrate suppress the temperature rapidly and the high temperature hasn't been observed experimentally.Therefore,the effects of carrier concentration and stress is uncertain.We expected that inducing superconductivity in ar-senene through electron doping and stress,and find the effects of these two methods,which will give some positive advices on experiments.Density functional theory is a well-developed and mature theory to cal-culate materials properties.The core idea of this theory is replacing the wave functions which contain 3N degrees by charge density which contains only 3degrees to describe interacting fermions system which is greatly simplifies the calculations.Kohn-Sham theory suggests that put the many-body interacting term in the exchange-correlation term to get the non-interacting electrons sys-tem under effective potential rather than N-electrons interacting system and get Kohn-Sham functions.Solving these self-consistent Kohn-Sham functions we will finally get requiring physical quantities.Density functional perturba-tion theory can gain the phonon frequencies by solving secular equation which obtained by calculating the linear response between charge density and force.And calculated electron-phonon coupling data through Eliashberg theory and find the properties of materials'superconductivity.In order to introduce the superconductivity,the electron and phonon properties of electron-doped arsenene is studied by first principle density func-tion theory.The electron-doped arsenene will become phonon-mediated su-perconductor.And the main contribution accounts for superconductivity of phonon is the A₁mode at K point while the electron coupling most with phonon is the arsenic p_z-like orbits.Meanwhile,the calculation results showed that the transition temperature will above 4.7 K without stress when the dop-ing is 0.2 electron per unit cell which the temperature is higher than liquid helium.Further increase the doping concentration to 0.2 electron per unit cell and apply 12%biaxial tensile stress will enhance the temperature to as high as about 30 K.Since the relatively small doping concentration,easier stress condition and stable gray arsenic as precursor,it can be expected to be observed in experiment.