Disorder driven transition beyond two-component, single-flavor Dirac physics in silicene

12th Europhysical Conference on Defects in Insulating Materials

材料科学;物理学

Goswami, Partha^1

Deshbandhu College, University of Delhi, Kalkaji, New Delhi

110019, India^1

关键词: Band insulators;    Dirac fermions;    Enhanced scattering;    Intrinsic spin-orbit couplings;    Orbit coupling;    Spin-orbit couplings;    Spin-polarized;    Topological insulators;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/80/1/012006/pdf
DOI  :  10.1088/1757-899X/80/1/012006

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

We consider the topological insulator (TI) phase of silicenein the presence of an applied electric field Ezperpendicular to its plane. These are assembly of Dirac fermions on a low-buckled 2D hexagonal lattice. The buckled structure generates a staggered sub-lattice potential between silicon atoms at A sites and B sites for the applied field. The starting point of our investigation is the Hamiltonian involving the Dirac kinetic energy, a mass gap term, and the spin-orbit coupling. Tuning of Ezallows for rich behaviour starting from a TI state to a band insulator(BI)with a valley-spin-polarized metal (VSPM) at a critical value in between. As long as the impurity potential strength V0is of the same order as the intrinsic spin-orbit coupling (SOC) tso(∼ 4 meV), VSPM phase is protected. The effective "two-component, single-flavorDirac physics" remains valid in this phase.Theincrease in V0, however, leads to the disappearance of this phase due to enhanced scattering processes, i.e. the out-of-plane electric field driven topological insulator to metal transition, being predicted for our system, will not be observable when the impurity potential is very high. The enhancement in SOC (tso) or the Rashbaspin-orbit coupling effect (t2), however, does not lead to such a scenario.