Spin-orbit-induced gap modification in buckled honeycomb XBi and XBi₃(X  =  B, Al, Ga, and In) sheets

Abstract

The band structure and stability of XBi and XBi3 (X = B, Al, Ga, and In) single sheets are predicted using first-principles calculations. It is demonstrated that the band gap values of these new classes of two-dimensional (2D) materials depend on both the spin-orbit coupling (SOC) and type of group-III elements in these hetero-sheets. Thus, topological properties can be achieved, allowing for viable applications based on coherent spin transport at room temperature. The spin-orbit effects are proved to be essential to explain the tunability by group-III atoms. A clear effect of including SOC in the calculations is lifting the spin degeneracy of the bands at the  of the Brillouin zone. The nature of the band gaps, direct or indirect, is also tuned by SOC, and by the appropriate X element involved. It is observed that, in the case of XBi single sheets, band inversions naturally occur for GaBi and InBi, which exhibit band gap values around 172 meV. This indicates that these 2D materials are potential candidates for topological insulators. On the contrary, a similar type of band inversion, as obtained for the XBi, was not observed in the XBi3 band structure. In general, the calculations, taking into account SOC, reveal that some of these buckled sheets exhibit sizable gaps, making them suitable for applications in room-temperature spintronic devices.

Twin Domain Structure in Magnetically Doped Bi2Se3 Topological Insulator

“…Calculations were treated in the scalar relativistic approximation, where on-site spin-orbit coupling was involved into the scalar relativistic Hamiltonian as a perturbation. An inclusion of spin-orbit coupling is needed to achieve a proper description of the electronic structure [ 5 , 8 , 47 ]. A basic screened impurity model was included to improve treating electrostatics of disordered systems [ 48 ].…”

Spin Polarization Properties of Pentagonal PdSe2 Induced by 3D Transition-Metal Doping: First-Principles Calculations

“…In our first-principles calculations, we adopt the Vienna Ab Initio Simulation Package (VASP) equipped with the projector-augmented-wave (PAW) method to study the electron-ion interactions [34]. The Perdew-Burke-Ernzerh (PBE) functional of the generalized gradient approximation (GGA) is considered to treat the electron exchange correlation, which produces the correct ground-state structure of the combined systems [35,36,37]. In our calculations, the model of the 2 × 2 × 1 pristine single-layer PdSe 2 (24 atoms) is given, the distance between adjacent PdSe 2 layer set as 20 Å to avoid the effects induced by periodic boundary conditions.…”

Theoretical Investigations of the Hexagonal Germanium Carbonitride

“…In addition, the effects of temperature and pressure on the Debye temperature, thermal expansion coefficient, heat capacity, and Grüneisen parameters were discussed in detail utilizing the quasi-harmonic Debye model. In addition, other III–V group compounds have also been studied extensively, including three-dimensional materials [ 17 , 18 , 19 , 20 , 21 , 22 ] and some low-dimensional materials, such as few-layer h -AlN [ 23 ], buckled honeycomb XBi and XBi 3 (X = B, Al, Ga, and In) sheets [ 24 ], and buckled III-Bi sheets [ 25 ].…”