Mechanical and electronic properties of pristine and Ni-doped Si, Ge, and Sn sheets

Abstract

Silicene, a graphene analogue of silicon, has been generating immense interest due to its potential for applications in miniaturized devices. Unlike planar graphene, silicene prefers a buckled structure. Here we explore the possibility of stabilizing the planar form of silicene by Ni doping using first principles density functional theory based calculations. It is found that planar as well as buckled structure is stable for Ni-doped silicene, but the buckled sheet has slightly lower total energy. The planar silicene sheet has unstable phonon modes. A comparative study of the mechanical properties reveals that the in-plane stiffness of both the pristine and the doped planar silicene is higher compared to that of the buckled silicene. This suggests that planar silicene is mechanically more robust. Electronic structure calculations of the planar and buckled Ni-doped silicene show that the energy bands at the Dirac point transform from linear behavior to parabolic dispersion. Furthermore, we extend our study to Ge and Sn sheets that are also stable and the trends of comparable mechanical stability of the planar and buckled phases remain the same.

Elemental Analogues of Graphene: Silicene, Germanene, Stanene, and Phosphorene

“…The classic composite structures of Group IV elements form YX and YX 3 structures (where Y = B, C, N, Al, P, Ni, Fe, and Co) . Typical atomic arrangements of YX and YX 3 are depicted in Figure b.…”

Induce magnetism into silicene by embedding transition-metal atoms

“…[25][26][27] In the case of graphene, SV can result in local magnetic moment without any TM impurity, 28 but for silicene, SV defect retains the nonmagnetic behavior. 26 In the past years, metal atoms adsorbed on silicene surface has been proposed, [29][30][31][32][33] but the study of transition metal atoms doped into the vacancy site of silicene is rare. 34 Here, we systematically performed first-principles calculations to explore the structures and magnetic properties of TM atoms from Sc to Zn embedded into silicene with SV and DV defects.…”

Physically founded phonon dispersions of few-layer materials and the case of borophene

“…[13][14][15] It is therefore surprising that no consensus exists as to whether unstrained few-layer systems should always display one flexural phonon branch with quadratic phonon dispersion at long wavelengths, even though this is what elasticity theory predicts. [16] Indeed, many recent abinitio calculations report three linear-dispersion acoustic branches (silicene, [17][18][19] [24]), whereas some other abinitio calculations, and virtually every empirical potential calculation, report one quadratic and two linear acoustic branches (silicene, [25] phosphorene, [26,27] [28]). Arguments have even been given to suggest that in a buckled system the flexural branch dispersion should no longer be quadratic.…”