[ASAP] Beyond Graphene: Chemistry of Group 14 Graphene Analogues: Silicene, Germanene, and Stanene
ACS NanoDOI: 10.1021/acsnano.9b04466
Published in: "ACS Nano".
Spin-orbit coupling in elemental two-dimensional materials. (arXiv:1907.05152v1 [cond-mat.mes-hall])
The fundamental spin-orbit coupling and spin mixing in graphene and rippled honeycomb lattice materials silicene, germanene, stanene, blue phosphorene, arsenene, antimonene, and bismuthene is investigated from first principles. The intrinsic spin-orbit coupling in graphene is revisited using multi-band $kcdot p$ theory, showing the presence of non-zero spin mixing in graphene despite the mirror symmetry. However, the spin mixing itself does not lead to the the Elliott-Yafet spin relaxation mechanism, unless the mirror symmetry is broken by external factors. For other aforementioned elemental materials we present the spin-orbit splittings at relevant symmetry points, as well as the spin admixture $b^2$ as a function of energy close to the band extrema or Fermi levels. We find that spin-orbit coupling scales as the square of the atomic number Z, as expected for valence electrons in atoms. For isolated bands, it is found that $b^2sim Z^4$. The spin-mixing parameter also exhibits giant anisotropy which, to a large extent, can be controlled by tuning the Fermi level. Our results for $b^2$ can be directly transferred to spin relaxation time due to the Elliott-Yafet mechanism, and therefore provide an estimate of the upper limit for spin lifetimes in materials with space inversion center.
Published : "arXiv Mesoscale and Nanoscale Physics".
Hematene: a 2D magnetic material in van der Waals or non-van der Waals heterostructures
In this article, we study theoretically the properties of hematene, a new antiferromagnetic 2D material exfoliated from hematite. Hematene is not a van-der Waals material, but it can still be obtained by liquid exfoliation of hematite crystals. Its properties might be quite different from those of the bulk and to establish such differences is one of the aims of this study. A detailed study of hematene by density functional theory has been carried out to look at the electronic properties of this iron oxide material. Results show that freestanding hematene is antiferromagnetic with a magnetic moment of 4 ##IMG## [http://ej.iop.org/images/2053-1583/6/4/045002/tdmab2501ieqn001.gif] per atom and an insulator/semiconductor with a bandgap of almost 1.0 eV. The stability of hematene is confirmed by calculating its phonon spectrum. Hematene supported on gold and stanene was also investigated: while no significant changes are found for the contact with the former,…
Published in: "2DMaterials".
Estudio del crecimiento del Sn/Ag(111): explorando la posibilidad de formacion de estaneno. (arXiv:1906.01159v1 [cond-mat.mes-hall])
In recent years, 2D materials have attracted increasing attention from the scientific community due to their superlative properties. The stanene, a graphene like compound formed by Sn atoms, may have unique properties because of the spin-orbit coupling SOC (such as the Quantum Spin Hall Effect QSH, topological superconductivity, among others), that could eventually have applications in spintronics and quantum computing. In the experiment stanene epitaxial growth was explored by evaporating Sn onto a Ag(111) substrate. Partial results using spectroscopic techniques such as LEED and XPS agreed with literature. Regarding measurements made with UPS/ARPES, dispersion relations were obtained for the surface state of the Sn/Ag(111) sample: for 1/3ML of Sn they matched with the reported results for the surface alloy Ag$_2$Sn; conversely, for (1/3+0,5)ML of Sn they mismatched with the reported parabolic relation for the stanene, particularly, they were indistinguishable from the surface alloy one. Probably, lack of formation of stanene was caused by an excessive heating during the sample preparation process, that could have produced an increase in the surface alloy Ag$_2$Sn thickness.
Published : "arXiv Mesoscale and Nanoscale Physics".
Tuning the structural and electronic properties and chemical activities of stanene monolayers by embedding 4d Pd: a DFT study
RSC Adv., 2019, 9,16069-16082DOI: 10.1039/C9RA01472A, Paper Open Access   This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Amirali AbbasiThe structural, electronic and chemical activities of stanene monolayers can be effectively tuned by introducing Pd atoms.The content of this RSS Feed
Published in: "RSC Advances".
High-temperature tunable superfluidity of polaritons in $mathrm{Xene}$ monolayers in an optical microcavity
Author(s): Matthew N. Brunetti, Oleg L. Berman, and Roman Ya. KezerashviliWe study tunable polaritons in monolayers of silicene, germanene, and stanene (Xenes) via an external electric field in an open optical microcavity whose length can be adjusted. An external electric field applied perpendicular to the plane of the Xene monolayer simultaneously changes the band gap an…[Phys. Rev. B 99, 195417] Published Mon May 13, 2019
Published in: "Physical Review B".
Spin-valley coupled thermoelectric energy converter with strained honeycomb lattices. (arXiv:1905.00984v1 [cond-mat.mtrl-sci])
A caloritronic device setup is proposed that harnesses the intrinsic spin-valley locking of two-dimensional honeycomb lattices with graphene-like valleys, for instance, silicene and stanene. Combining first-principles and analytic calculations, we quantitatively show that when sheets of such materials are placed on a ferromagnetic substrate and held between two contacts at different temperatures, an interplay between the electron degrees-of-freedom of charge, spin, and valley arises. A manifestation of this interplay are finite charge, spin, and valley currents. Uniaxial strain that adjusts the buckling height in silicene-type of lattices, in conjunction with an applied electric field, is shown to further modulate the aforementioned currents. We link these calculations to a Seebeck-like thermopower generator and obtain expressions (and means to optimize them) for two spin-valley polarized performance metrics–the thermodynamic efficiency and thermoelectric figure of merit. A closing summary outlines possible enhancements to presented results through the inherent topological order and substrate-induced external Rashba spin-orbit coupling that exists in silicene-type materials.
Published in: "arXiv Material Science".
Symmetry-adapted real-space density functional theory for cylindrical geometries: application to large X (X=C, Si, Ge, Sn) nanotubes. (arXiv:1904.13356v1 [cond-mat.mes-hall])
We present a symmetry-adapted real-space formulation of Kohn-Sham density functional theory for cylindrical geometries and apply it to the study of large X (X=C, Si, Ge, Sn) nanotubes. Specifically, starting from the Kohn-Sham equations posed on all of space, we reduce the problem to the fundamental domain by incorporating cyclic and periodic symmetries present in the angular and axial directions of the cylinder, respectively. We develop a real-space parallel implementation of this formulation, and verify its accuracy against established codes. Using this implementation, we study the band structure and bending properties of X nanotubes and Xene sheets, respectively. Specifically, we first show that zigzag and armchair X nanotubes with radii in the range $1$ to $5$ nm are semiconducting. We find an inverse linear dependence of the bandgap with respect to radius for all nanotubes other than the armchair and zigzag type III carbon variants, for which we find an inverse quadratic dependence. Next, we exploit the connection between cyclic symmetry and uniform bending deformations to calculate the bending moduli of Xene sheets in both zigzag and armchair directions. We find Kirchhoff-Love type bending behavior, with graphene and stanene possessing the largest and smallest moduli, respectively. In addition, other than graphene, the sheets demonstrate significant anisotropy, with larger bending moduli along the armchair direction. Finally, we demonstrate that the proposed approach has very good parallel scaling and is highly efficient, enabling ab initio simulations of unprecedented size for systems with a high degree of cyclic symmetry. In particular, we show
Published : "arXiv Mesoscale and Nanoscale Physics".
Tunnel-Field-Effect Spin Filter from Two-Dimensional Antiferromagnetic Stanene. (arXiv:1904.09254v1 [cond-mat.mes-hall])
We propose a device concept, based on monolayer stanene, able to provide highly polarized spin currents (up to a $98%$) with voltage-controlled spin polarization operating at room temperature and with small operating voltage ($0.3$ V). The concept exploits the presence of spin-polarized edge states in a stanene nanoribbon. The spin polarization of the total current can be modulated by a differential tuning of the transmission properties, and of the occupation of edge states of different spin, via the application of an in-plane electric field. We demonstrate device operation using ab-initio and quantum transport simulations.
Published : "arXiv Mesoscale and Nanoscale Physics".
High-temperature tunable superfluidity of polaritons in Xene monolayers in an optical microcavity. (arXiv:1903.09861v1 [cond-mat.mes-hall])
We study tunable polaritons in monolayers of silicene, germanene, and stanene (Xenes) via an external electric field in an open optical microcavity whose length can be adjusted. An external electric field applied perpendicular to the plane of the Xene monolayer simultaneously changes the band gap and the exciton binding energy, while the variable length of the open microcavity allows one to keep the exciton and cavity photon modes in resonance. First, the Schr”{o}dinger equation for an electron and hole in an Xene monolayer is solved, yielding the eigenergies and eigenfunctions of the exciton as a function of the external electric field. The dependence of the polaritonic properties, such as the Rabi splitting and cavity photon damping, on the external electric field and on the cavity length, is analyzed. The Berezinskii-Kosterlitz-Thouless (BKT) transition temperature of polaritons is calculated as a function of the external electric field. We analyze and present the conditions for a room-temperature superfluid of lower polaritons by simultaneously maximizing the Rabi splitting and BKT transition temperature.
Published : "arXiv Mesoscale and Nanoscale Physics".
Facile Fabrication of 2D Stanene Nanosheets via Dealloying Strategy for Potassium Storage
Chem. Commun., 2019, Accepted ManuscriptDOI: 10.1039/C9CC00332K, CommunicationJingui Ma, Jianan Gu, Bin Li, Shubin YangIn this work, a facile dealloying strategy was developed to large scale fabricate 2D stanene nanosheets in ambient condition. The obtained stanene exhibited typical 2D structure with a thickness of…The content of this RSS Feed (c) The Royal Society of Chemistry
Published in: "Chemical Communications".
Higher harmonic generation by massive carriers in buckled two-dimensional hexagonal nanostructures
Author(s): H. K. Avetissian and G. F. MkrtchianGeneration of high harmonics in novel two-dimensional (2D) nanostructures such as silicene, germanene, and stanene initiated by strong coherent electromagnetic radiation of arbitrary polarization, taking into account the spin-orbit coupling and the buckling of two Bravais lattices, is investigated. …[Phys. Rev. B 99, 085432] Published Wed Feb 20, 2019
Published in: "Physical Review B".
Giant Seebeck magnetoresistance triggered by electric field and assisted by a valley through a ferromagnetic/antiferromagnetic junction in heavy group-IV monolayers
Author(s): Xuechao Zhai, Junwei Gu, Rui Wen, Ruo-Wen Liu, Min Zhu, Xingfei Zhou, L.-Y. Gong, and Xing’ao LiElectrons in heavy group-IV monolayers, including silicene, germanene, and stanene, have the ability to exhibit rich physics due to the compatibility of the spin and valley degrees of freedom. We propose here that a valley-mediated giant Seebeck magnetoresistance (MR) effect, triggered and controlle…[Phys. Rev. B 99, 085421] Published Tue Feb 19, 2019
Published in: "Physical Review B".
Towards topological quasifreestanding stanene via substrate engineering
Author(s): Domenico Di Sante, Philipp Eck, Maximilian Bauernfeind, Marius Will, Ronny Thomale, Jörg Schäfer, Ralph Claessen, and Giorgio SangiovanniIn 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 hexa…[Phys. Rev. B 99, 035145] Published Wed Jan 23, 2019
Published in: "Physical Review B".
Composition and Stacking Dependent Topology in Bilayers from the Graphene Family. (arXiv:1811.05525v1 [cond-mat.mtrl-sci])
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
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])
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])
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".
[ASAP] Chemically Functionalized Penta-stanene Monolayers for Light Harvesting with High Carrier Mobility
The Journal of Physical Chemistry CDOI: 10.1021/acs.jpcc.8b06282
Published in: "The Journal of Physical Chemistry C".
Thermal transport characterization of carbon and silicon doped stanene nanoribbon: an equilibrium molecular dynamics study
RSC Adv., 2018, 8,31690-31699DOI: 10.1039/C8RA06156D, Paper Open Access   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".