Achieving controllable multifunctionality through layer sliding

Abstract

Dynamical variation of physical properties in a controllable fashion provides exciting possibilities to obtain multifunctional materials. In this work, layer-sliding is employed to modify the structural, interfacial electronic and optical properties of unintercalated and Mg-intercalated two-dimensional (2D) van der Waals heterostructure (vdW-HS) consisting of buckled silicene and hexagonal boron nitride (hBN). The most stable stacking configuration of silicene over hBN is screened out and then intercalated with Mg at the interface. Dynamical-dependent changes in the properties of vdW-HS are performed by sliding silicene over hBN monolayer in the absence and presence of the intercalant. Layer-sliding is carried out in equal length intervals, and various parametric quantities related to the physical characteristics of the vdW-HS are repeatedly calculated and compared. Apart from various parametric quantities, stability of unintercalated and Mg-intercalated vdW-HS is also checked by means of relative total energies, binding energies and vdW gaps along the sliding pathway. Comparison of binding energies shows that the un-slided, half-slided, and fully-slided Mg-intercalated vdW-HS are 1.52, 1.44 and 1.42 eV more stable than the unintercalated vdW-HS. Opening of a small band gap of 12, 31 and 28 meV for un-slided, half-slided and fully-slided unintercalated vdW-HS, respectively, is worth mentioning. To study the interfacial electronic behavior, planar average charge density difference (Δρ) and charge transfer (ΔQ) are also calculated and varied via layer-sliding. Further, we calculated diverse optical spectra such as the complex dielectric function (DF), electron energy loss function [L(ω)], diagonal components of dielectric tensor [ε(iω)], refractive index [n(ω)], extinction coefficient [k(ω)], absorption coefficient [α(ω)], and reflectivity [R(ω)] for un-slided, half-slided and fully-slided unintercalated and Mg-intercalated vdW-HS. Interestingly, the polarization and energy losses have been reduced in the case of Mg-intercalated vdW-HS. The suggested layer-sliding method can be established as a general scheme for bringing multifunctionality into a layered material.