/Tag: stanene

Composition and Stacking Dependent Topology in Bilayers from the Graphene Family. (arXiv:1811.05525v1 [cond-mat.mtrl-sci])

2018-11-15T02:29:17+00:00November 15th, 2018|Categories: Publications|Tags: , , |

We present a compositional and structural investigation of silicene, germanene, and stanene bilayers from first-principles. Due to the staggering of the individual layers, several stacking patterns are possible, most of which are not available to the bilayer graphene. This structural variety, in conjunction with the presence of the spin-orbit coupling, unveil a diversity of the electronic properties, with the appearance of distinct band features, including orbital hybridization and band inversion. We show that for particular cases, the intrinsic spin Hall response exhibits signatures of non-trivial electronic band topology, making these structures promising candidates to probe Dirac-like physics.

Published in: "arXiv Material Science".

Epitaxial growth of ultraflat stanene with topological band inversion

2018-11-05T16:34:21+00:00November 5th, 2018|Categories: Publications|Tags: |

Epitaxial growth of ultraflat stanene with topological band inversionEpitaxial growth of ultraflat stanene with topological band inversion, Published online: 05 November 2018; doi:10.1038/s41563-018-0203-5A flat stanene layer can be grown on Cu (111) by MBE growth, exhibiting topological properties as revealed by a combination of ARPES, STM and DFT calculations.

Published in: "Nature Materials".

Origin of topologically trivial states and topological phase transitions in low-buckled plumbene. (arXiv:1810.02934v1 [cond-mat.mtrl-sci])

2018-10-09T02:29:31+00:00October 9th, 2018|Categories: Publications|Tags: , |

Combining tight-binding (TB) models with first-principles calculations, we investigate electronic and topological properties of plumbene. Different from the other two-dimensional (2D) topologically nontrivial insulators in group IVA (from graphene to stanene), low-buckled plumbene is a topologically trivial insulator. The plumbene without spin-orbit coupling exhibits simultaneously two kinds of degeneracies, i.e., quadratic non-Dirac and linear Dirac band dispersions around the Gamma and K/K’ points, respectively. Our TB model calculations show that it is the coupling between the two topological states around the Gamma and K/K’ points that triggers the global topologically trivial property of plumbene. Quantum anomalous Hall effects with Chern numbers of 2 or -2 can be, however, achieved after an exchange field is introduced. When the plumbene is functionalized with ethynyl (PbC2H), quantum spin Hall effects appear due to the breaking of the coupling effect of the local topological states.

Published in: "arXiv Material Science".

Influence of edge magnetization and electric fields on zigzag silicene, germanene and stanene nanoribbons. (arXiv:1810.00628v1 [cond-mat.mes-hall])

2018-10-02T04:30:59+00:00October 2nd, 2018|Categories: Publications|Tags: , , |

Using a multi-orbital tight-binding model, we have studied the edge states of zigzag silicene, germanene, and stanene nanoribbons (ZSiNRs, ZGeNRs and ZSnNRs, respectively) in the presence of the Coulomb interaction and a vertical electric field. The resulting edge states have non-linear energy dispersions due to multi-orbital effects, and the nanoribbons show induced magnetization at the edges. Owing to this non-linear dispersion, ZSiNRs, ZGeNRs and ZSnNRs may not provide superior performance in field effect transistors, as has been proposed from single-orbital tight-binding model calculations. We propose an effective low-energy model that describes the edge states of ZSiNRs, ZGeNRs, and ZSnNRs. We demonstrate that the edge states of ZGeNR and ZSnNR show anti-crossing of bands with opposite spins, even if only out-of-plane edge magnetization is present. The ability to tune the spin polarizations of the edge states by applying an electric field points to future opportunities to fabricate silicene, germanene and stanene nanoribbons as spintronics devices.

Published : "arXiv Mesoscale and Nanoscale Physics".

Thermal transport characterization of carbon and silicon doped stanene nanoribbon: an equilibrium molecular dynamics study

2018-09-12T10:32:30+00:00September 12th, 2018|Categories: Publications|Tags: |

RSC Adv., 2018, 8,31690-31699DOI: 10.1039/C8RA06156D, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Ishtiaque Ahmed Navid, Samia SubrinaTunable thermal transport of doped stanene nanoribbon considering the impact of doping concentration, doping pattern, temperature and nanoribbon width.The

Published in: "RSC Advances".

Optical properties of excitons in buckled two-dimensional materials in an external electric field

2018-09-07T14:33:38+00:00September 7th, 2018|Categories: Publications|Tags: , , |

Author(s): Matthew N. Brunetti, Oleg L. Berman, and Roman Ya. KezerashviliWe study the binding energies and optical properties of direct and indirect excitons in monolayers and double-layer heterostructures of Xenes: silicene, germanene, and stanene. It is demonstrated that an external electric field can be used to tune the eigenenergies and optical properties of excitons…[Phys. Rev. B 98, 125406] Published Fri Sep 07, 2018

Published in: "Physical Review B".

Towards Topological Quasi-Freestanding Stanene via Substrate Engineering. (arXiv:1807.09006v1 [cond-mat.mtrl-sci])

2018-07-25T02:29:32+00:00July 25th, 2018|Categories: Publications|Tags: , , |

In search for a new generation of spintronics hardware, material candidates for room temperature quantum spin Hall effect (QSHE) have become a contemporary focus of investigation. Inspired by the original proposal for QSHE in graphene, several heterostructures have been synthesized, aiming at a hexagonal monolayer of heavier group IV elements in order to promote the QSHE bulk gap via increased spin-orbit coupling. So far, however, the monolayer/substrate coupling, which can manifest itself in strain, deformation, and hybridization, has proven to be detrimental to the aspired QSHE conditions for the monolayer. Specifically focusing on stanene, the Sn analogue of graphene, we investigate how an interposing buffer layer mediates between monolayer and substrate in order to optimize the QSHE setting. From a detailed density functional theory study, we highlight the principal mechanisms induced by such a buffer layer to accomplish quasi-free standing stanene in its QSHE phase. We complement our theoretical predictions by presenting the first real attempts to grow a buffer layer on SiC(0001) on which stanene can be deposited.

Published in: "arXiv Material Science".

On the Optical Properties of Excitons in Buckled 2D Materials in an External Electric Field. (arXiv:1807.00407v1 [cond-mat.mes-hall])

2018-07-03T02:29:21+00:00July 3rd, 2018|Categories: Publications|Tags: , , |

We study the binding energies and optical properties of direct and indirect excitons in monolayers and double layer heterostructures of Xenes: silicene, germanene, and stanene. It is demonstrated that an external electric field can be used to tune the eigenenergies and optical properties of excitons by changing the effective mass of charge carriers. The Schr”{o}dinger equation with field-dependent exciton reduced mass is solved by using the Rytova-Keldysh (RK) potential for direct excitons, while both the RK and Coulomb potentials are used for indirect excitons. It is shown that for indirect excitons, the choice of interaction potential can cause huge differences in the eigenenergies at large electric fields and significant differences even at small electric fields. Furthermore, our calculations show that the choice of material parameters has a significant effect on the binding energies and optical properties of direct and indirect excitons. These calculations contribute to the rapidly growing body of research regarding the excitonic and optical properties of this new class of two dimensional semiconductors.

Published in: "arXiv Material Science".

Enhanced Electron Transport in Thin Copper Films via Atomic-Layer Materials Capping. (arXiv:1805.01517v1 [cond-mat.mtrl-sci])

2018-05-07T19:59:08+00:00May 7th, 2018|Categories: Publications|Tags: , , |

Using first-principles calculations based on density functional theory and non-equilibrium Green’s functions, we characterized the effect of surface termination on the electronic transport properties of nanoscale Cu slabs. With ideal, clean (111) surfaces and oxidized ones as baselines we explore the effect of capping the slabs with graphene, hexagonal boron nitrate, molybdenum disulfide and stanene. Surface oxide suppresses balistic conductance by a factor of 10 compared to the ideal surface. Capping the ideal copper surface with graphene slightly increase conductance but MoS$_2$ and stanene have the opposite effect due to stronger interactions at the interface. Interestingly, we find that capping atomistically roughed copper surfaces with graphene or MoS$_2$ decreases the resistance per unit length by 20 and 13%, respectively, due to reduced scattering. The results presented in this work suggest that two-dimensional materials can be used as an ultra-thin liner in metallic interconnect technology without increasing the interconnect line resistivity significantly.

Published in: "arXiv Material Science".

First principle investigation of Tunnel FET based on nanoribbons from topological two-dimensional material. (arXiv:1804.03440v1 [cond-mat.mes-hall])

2018-04-11T19:58:57+00:00April 11th, 2018|Categories: Publications|Tags: |

We explore nanoribbons from topological two-dimensional stanene as channel material in tunnel field effect transistors. This novel technological option offers the possibility to build pure one-dimensional (1D) channel devices (comprised of a 1D chain of atoms) due to localized states in correspondence of the nanoribbon edges. The investigation is based on first-principle calculations and multi-scale transport simulations to assess devices performance against industry requirements and their robustness with respect to technological issues like line edge roughness, detrimental for nanoribbons. We will show that edges states are robust with respect to the presence of non-idealities (e.g., atoms vacancies at the edges), and that 1D-channel TFETs exhibit interesting potential for digital applications and room for optimization in order to improve the Ion/Ioff at the levels required by the ITRS, while opening a path for the exploration of new device concepts at the ultimate scaling limits.

Published : "arXiv Mesoscale and Nanoscale Physics".

Stanene Nanomesh as Anode Material for Na-ion Batteries

2018-03-31T23:13:45+00:00March 31st, 2018|Categories: Publications|Tags: , |

J. Mater. Chem. A, 2018, Accepted ManuscriptDOI: 10.1039/C8TA01716F, PaperLiyuan Wu, Pengfei Lu, Ruge Quhe, qian wang, Chuanghua Yang, Pengfei Guan, Kesong YangTwo-dimensional (2D) materials are showing promising potential in the energy storage applications such as being as electrodes of metal-ion batteries. Here, we

Published in: "Journal of Materials Chemistry A".

Thermal transport characterization of stanene/silicene heterobilayer and stanene bilayer nanostructures

2018-03-08T14:31:14+00:00March 8th, 2018|Categories: Publications|Tags: , , |

Recently, stanene and silicene based nanostructures with low thermal conductivity have incited noteworthy interest due to their prospect in thermoelectrics. Aiming at the possibility of extracting lower thermal conductivity, in this study, we have proposed and modeled stanene/silicene heterobilayer nanoribbons, a new heterostructure and subsequently characterized their thermal transport by using an equilibrium molecular dynamics simulation. In addition, the thermal transport in bilayer stanene is also studied and compared. We have computed the thermal conductivity of the stanene/silicene and bilayer stanene nanostructures to characterize their thermal transport phenomena. The studied nanostructures show good thermal stability within the temperature range of 100–600 K. The room temperature thermal conductivities of pristine 10 nm × 3 nm stanene/silicene hetero-bilayer and stanene bilayer are estimated to be 3.63 ± 0.27 W m −1 K −1 and 1.31 ± 0.34 W m −1

Published in: "Nanotechnology".

Semimetal behavior of bilayer stanene. (arXiv:1802.01351v1 [cond-mat.mes-hall])

2018-02-06T19:59:06+00:00February 6th, 2018|Categories: Publications|Tags: , |

Stanene is a two-dimensional (2D) buckled honeycomb structure which has been studied recently owing to its promising electronic properties for potential electronic and spintronic applications in nanodevices. In this article, we present a first-principles study of electronic properties of fluorinated bilayer stanene. The effect of tensile strain, intrinsic spin-orbit, and van der Waals interactions are considered within the framework of density functional theory. The electronic band structure shows a very small overlap between valence and conduction bands at the {Gamma} point which is a characteristic of semimetal in fluorinated bilayer stanene. A relatively high value of tensile strain is needed to open an energy band gap in the electronic band structure and the parity analysis reveals that the strained nanostructure is a trivial insulator. According to our results, despite the monolayer fluorinated stanene, the bilayer one is not an appropriate candidate for topological insulator.

Published : "arXiv Mesoscale and Nanoscale Physics".

Superconductivity in few-layer stanene

2018-01-15T18:31:54+00:00January 15th, 2018|Categories: Publications|Tags: |

Superconductivity in few-layer staneneSuperconductivity in few-layer stanene, Published online: 15 January 2018; doi:10.1038/s41567-017-0031-6Stanene is a single sheet of tin atoms. Here, it is shown that a few stacked layers of stanene can be a superconductor. Changing the thickness of the substrate modifies the form of superconductivity and critical temperature.

Published in: "Nature Physics".

Gapped electronic structure of epitaxial stanene on InSb(111)

2018-01-11T16:30:37+00:00January 11th, 2018|Categories: Publications|Tags: , |

Author(s): Cai-Zhi Xu, Yang-Hao Chan, Peng Chen, Xiaoxiong Wang, David Flötotto, Joseph Andrew Hlevyack, Guang Bian, Sung-Kwan Mo, Mei-Yin Chou, and Tai-Chang ChiangStanene, a single tin atomic layer akin to graphene, is a quantum spin Hall insulator. Its spin-polarized edge states within the gap would be well suited for spintronic applications, but this attractive property has not been realized because the substrate for supporting stanene in prior experiments leads to a metallic contact that fills the band gap and shorts out the quantum spin Hall channels. By judiciously selecting InSb(111) as the substrate, the resulting system shows a large gap of 0.44 eV well suited for room-temperature device operations. Stanene on InSb(111) is thus a strong contender for next-generation spintronic technology.[Phys. Rev. B 97, 035122] Published Thu Jan 11, 2018

Published in: "Physical Review B".

Stanene grows on silver

2018-01-06T00:29:18+00:00January 5th, 2018|Categories: News|Tags: , |

Graphene’s heaviest cousin shows promise for nanoelectronics, spintronics and potential quantum-computing applications.

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