Ab initio study of the structural, electronic, magnetic, and optical properties of silicene nanoribbons

Abstract

We present first-principles calculations of structural, electronic, magnetic, and optical properties of zigzagoriented silicene nanoribbons, which, being endowed with spin-polarized edge states, are promising candidates as building blocks of future spintronic devices. The minimal width for a structurally stable planar structure having zigzag edges corresponds to a 4-chain ribbon, whose ground state presents antiferromagnetically coupled spin-polarized edges, and a lattice parameter along the nanoribbon axis contracted (∼5%) with respect to the bulk value. Starting from the dependence of structural and electronic properties on the ribbon width, we present theoretical predictions for the optical spectra of narrow nanoribbons, in which excitonic effects are relevant due to the confinement in a quasi-one-dimensional structure. Especially for light polarized parallel to the ribbon axis, we find significant differences in the position of optical absorption peaks of ribbons with ferroor antiferromagnetically coupled edges, showing that optical spectra can be used as a fingerprint of the magnetic coupling of electronic edge states.

First-Principles Calculations of the Effects of Edge Functionalization and Size on the Band Gap of Be3N2 Nanoribbons: Implications for Nanoelectronic Devices

“…More importantly, it is useful in estimating the critical property of semiconductors such as carrier mobility of holes and electrons along with the magnetic moment of an electron. The quantum confinement and edge hybridization are the cause of the width-dependent band gap (usually decreases with the 1/ W α approach) in NRs and need to be addressed in detail. , …”

“…The quantum confinement and edge hybridization are the cause of the width-dependent band gap (usually decreases with the 1/W α approach) in NRs and need to be addressed in detail. 49,50 Now, we turn our attention toward the width-dependent electronic band structure of H-, F-, and Cl-passivated ABe 3 N 2n and ZBe 3 N 2 -n NRs. We have calculated the electronic structure of all NRs along the high symmetry Γ−X path to examine the occurrence of modulation in the electronic nature and deviation in the band gap as a function of width.…”

Time-Dependent Density Functional Theory Investigation on the Electronic and Optical Properties of Poly-C,Si,Ge-acenes

“… 24 Further computational investigations on poly-Si,Ge-acenes 25 − 27 and silicene or germanene nanoribbons have been published over the years. 28 − 34 …”

“…Structural transition from non-planar to planar conformations in the Si 6– n C n H 6 ( n = 0–6) series was later investigated using higher-level coupled cluster methods, showing that deviation from planarity in hexasilabenzene is caused by the pseudo-Jahn–Teller effect . Further computational investigations on poly-Si,Ge-acenes − and silicene or germanene nanoribbons have been published over the years. − …”

Tuning the electronic properties ot two-dimensional systems

“…Calculations on silicene and germanene nanoribbons also predict more exotic electronic states, such as topological edge states, which can be tuned by the ribbon width [191], edge functionalization [192], the substrate [193], and external elec-93 tric [194] or magnetic fields [195]. Edge reconstructions can dramatically alter the electronic properties of the edges.…”