Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session V32: Computational Discovery and Design of Novel Materials XI |
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Sponsoring Units: DMP DCOMP Chair: Lilia Woods, Department of Physics, University of South Florida Room: 295 |
Thursday, March 16, 2017 2:30PM - 2:42PM |
V32.00001: Disorder effect on the anisotropic resistivity of phosphorene determined by a tight-binding model Carlos Paez, Kursti DeLello, Duy Le, Ana Pereira, Eduardo Mucciolo In this work we develop a compact multi-orbital tight-binding model for phosphorene that accurately describes states near the main band gap[1]. The model parameters are adjusted using as reference the band structure obtained by a density-functional theory calculation with the hybrid HSE06 functional. We use the optimized tight-binding model to study the effects of disorder on the anisotropic transport properties of phosphorene. In particular, we evaluate how the longitudinal resistivity depends on the lattice orientation for two typical disorder models: dilute scatterers with high potential fluctuation amplitudes, mimicking screened charges in the substrate, and dense scatterers with lower amplitudes, simulating weakly bounded adsorbates. We show that the intrinsic anisotropy associated to the band structure of this material, although sensitive to the type and intensity of the disorder, is robust. [1] Paez et al. Physical Review B, 94 (16) 165419 (2016) [Preview Abstract] |
Thursday, March 16, 2017 2:42PM - 2:54PM |
V32.00002: Temperature Effect on the Static Polarization of Monolayer and Bilayer Phosphorus Dipendra Dahal, Antonios Balassis, Godfrey Gumbs The polarizability of monolayer and bilayer phosphorus is calculated. Results will be presented at various temperatures as well as when a vertical electric field is applied. We employ our polarization function in calculating the static shielded potential of a nonmagnetic impurity in its vicinity. We also investigate the way in which this static shielding is modified for a scaffold structure involving a thick conductor forming a substrate for the phosphorus layers. Our calculations make use of the inverse dielectric function which we obtain in the random-phase approximation. We also report on our calculations when the impurity distance from the conductor surface or 2D layer is varied. [Preview Abstract] |
Thursday, March 16, 2017 2:54PM - 3:06PM |
V32.00003: Peculiar Piezoelectricity in Two-Dimensional Materials Cem Sevik, Deniz Cakir, Oguz Gulseren, Francois M. Peeters Recently, two dimensional materials with noncentrosymmetric structure have received significant interest due to their potential usage in piezoelectric applications. It has been reported by first principles calculations that relaxed-ion piezoelectric strain ($d_{11})$ and stress ($e_{11})$ coefficients of some transition metal dichalcogenide (TMDC) monolayers are comparable or even better than that of conventional bulk piezoelectric materials. Furthermore, $e_{11\thinspace }$coefficient of MoS$_{\mathrm{2}}$ has been measured as 2.9$\cdot $10$^{\mathrm{-10}}$ C/m, which agrees well with the theoretical calculations. In order to deeply investigate this potential, we have performed first-principles calculations and systematically investigated the piezoelectric properties of various single layer structures: TMDCs, transition metal oxides, and hexagonal group II-VI compounds. The results clearly show that not only the Mo- and W-based TMDCs but also the other materials with Cr, Ti, Zr and Sn exhibit highly promising piezoelectric properties. Moreover, $d_{11} $coefficient of some II-VI compounds have been predicted as quite larger than that of TMDCs and the bulk materials, $\alpha $-quartz,$w$-GaN, and $w$-AlN which are widely used in applications. [Preview Abstract] |
Thursday, March 16, 2017 3:06PM - 3:18PM |
V32.00004: Stability of two-dimensional BN-Si structures Ernesto Sandoval, Samad Hajinazar, Aleksey Kolmogorov We have used \textit{ab initio} modeling to examine stability factors in two-dimensional (2D) CSi, BNC$_{\mathrm{2}}$, and recently proposed BNSi$_{\mathrm{2}}$ honeycomb structures. We have found that the lack of miscibility in the last two systems is due to limited involvement of nitrogen electronic states in the covalent bonding. Our evolutionary ground state searches uncovered that in the (BN)$_{\mathrm{x}}$Si$_{\mathrm{1-x\thinspace }}$pseudobinary system non-honeycomb flat structures have lower energy than the graphene-like configurations. Nevertheless, none of these or previously proposed polymorphs have been found to be stable with respect to phase separation into 2D Si and BN. [Preview Abstract] |
Thursday, March 16, 2017 3:18PM - 3:30PM |
V32.00005: An Array of Layers in Silicon Sulfides: Chain-like and Ground State Structures Tom\'{a}s Alonso-Lanza, Andr\'{e}s Ayuela, Faustino Aguilera-Granja While much is known about isoelectronic materials related to carbon nanostructures, such as boron nitride layers and nanotubes, rather less is known about equivalent silicon based materials. Following the recent discovery of phosphorene, we here discuss isoelectronic silicon monosulfide monolayers. We describe a set of anisotropic ground state structures that clearly have a high stability with respect to the near isotropic silicon monosulfide monolayers. The source of the layer anisotropy is related to the presence of Si-S double chains linked by some Si-Si covalent bonds, which lie at the core of the increased stability, together with a remarkable \textit{spd} hybridization on Si. The involvement of \textit{d} orbitals brings more variety to silicon-sulfide based nanostructures that are isoelectronic to phosphorene, which could be relevant for future applications, adding extra degrees of freedom. [Preview Abstract] |
Thursday, March 16, 2017 3:30PM - 3:42PM |
V32.00006: Sulfur-doped Graphene Nanoribbons with a Sequence of Distinct Band Gaps Shi-Xuan Du, Yan-Fang Zhang, Yi Zhang, Reinhard Berger, Xinliang Feng, Klaus Mullen, Xiao Lin, Yu-Yang Zhang, Sokrates T. Pantelides, Hong-Jun Gao Unlike free-standing graphene, graphene nanoribbons (GNRs) can possess semiconducting band gap. However, achieving such control has been a major challenge in the fabrication of GNRs. Chevron-type GNRs were recently achieved by surface-assisted polymerization of pristine or N-substituted oligophenylene monomers. By mixing two different monomers, GNR heterojunctions can in principle be fabricated. Here we report fabrication and characterization of chevron-type GNRs by using sulfur-substituted oligophenylene monomers to achieve GNRs and related heterostructures for the first time. Importantly, our first-principles calculations show that the band gaps of GNRs can be tailored by different S configurations in cyclodehydrogenated isomers through debromination and intramolecular cyclodehydrogenation. This feature should open up new avenues to create multiple GNR heterojunctions by engineering the sulfur configurations. These predictions have been confirmed by Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). The unusual sequence of intraribbon heterojunctions may be useful for nanoscale optoelectronic applications based on quantum dots [Preview Abstract] |
Thursday, March 16, 2017 3:42PM - 3:54PM |
V32.00007: Tellurene: a New Family of Two Dimensional Group-VI Monolayer Driven by Multivalency Yu Jia, Zhili Zhu, Xiaolin Cai, Chunyao Niu, Seho Yi, Jun Hyung Cho, Zhengxiao Guo, Feng Liu, Zhengyu Zhang The exploration of two-dimensional (2D) layered materials is of fundamental and practical importance in contemporary condensed matter physics. Using the particle-swarm optimization method in combination with first-principles density functional theory calculations, we predict a new family of 2D monolayers composed of a group-VI element of Te. It is revealed that the multivalency character of Te plays a crucial role in forming monolayers with the 1T-MoS$_{\mathrm{2}}$-like (termed $\alpha $-Te), tetragonal ($\beta $-Te), and 2H-MoS$_{\mathrm{2}}$-like ($\gamma $-Te) structures. We find that $\alpha $- and $\beta $-Te are semiconductors, while $\gamma $-Te is metal. For $\alpha $- and $\beta $-Te, the spin-orbit coupling effects give a transformation from an indirect band gap into a nearly direct and a direct band gap, respectively, leading to an optical absorption enhancement. Moreover, the semiconducting Te monolayers exhibit high electron and hole mobilities ranging from hundreds to thousands of cm$^{\mathrm{2\thinspace }}$V$^{-}^{\mathrm{1\thinspace }}$s$^{-}^{\mathrm{1}}$, superior to MoS$_{\mathrm{2}}$ monolayer. Our findings further extend the realm of 2D materials to include group-VI monolayers whose electronic properties are promising for potential applications in optoelectronics and electronics. [Preview Abstract] |
Thursday, March 16, 2017 3:54PM - 4:06PM |
V32.00008: First-principle study on the transport property of stanene films Zhiwei Ding, Jiawei Zhou, Bolin Liao, Te-huan Liu, Gang Chen Stanene, a single layer of tin atoms, is a newly discovered 2D material that has captured much attention due to its unique property. It is a quantum spin Hall (QSH) insulator with a sizable bulk gap of 0.1 eV. In this study, using first-principle calculation, the transport property of stanene is investigated and explored. A high electron mobility is observed, which is out of expectation given its buckled mono-layer structure. In addition, its thermoelectric property can be effectively tuned by chemical functionalization and external strain. Our study suggests that stanene might be a promising material for thermoelectric applications. [Preview Abstract] |
Thursday, March 16, 2017 4:06PM - 4:18PM |
V32.00009: Tunable magnetic states on the zigzag edges of hydrogenated and halogenated group-IV nanoribbons Feng-Chuan Chuang, Tzu-Cheng Wang, Chia-Hsiu Hsu, Zhi-Quan Huang, Wan-Sheng Su, Guang-Yu Guo The magnetic and electronic properties of hydrogenated and halogenated group-IV zigzag nanoribbons (ZNRs) are investigated by first-principles density functional calculations. Fascinatingly, we find that all the ZNRs have magnetic edges with a rich variety of electronic and magnetic properties tunable by selecting the parent and passivating elements as well as controlling the magnetization direction and external strain. In particular, the electric property of the edge band structure can be tuned from the conducting to insulating with a band gap up to 0.7 eV, depending on the parent and passivating elements as well as the applied strain, magnetic configuration and magnetization orientation. The last controllability would allow us to develop magnetic on-off nano-switches. Furthermore, ZNRs such as SiI, Ge, GeI and SnH, have fully spin-polarized metallic edge states and thus are promising materials for spintronics. The calculated magnetocrystalline anisotropy energy can be as large as \textasciitilde 9 meV/edge-site, being 2000 time greater than that of bulk Ni and Fe (\textasciitilde 5 $\mu $eV/atom), and thus has great potential for high density magneto-electric data-storage devices. Finally, the calculated exchange coupling strength and thus magnetic transition temperature increases as the applied strain goes from -5 {\%} to 5 {\%}. Our findings thus show that these ZNRs would have exciting applications in next-generation electronic and spintronic nano-devices. [Preview Abstract] |
Thursday, March 16, 2017 4:18PM - 4:30PM |
V32.00010: Interplay of temperature, spatial dispersion, and topology in silicene Casimir interactions Lilia Woods, Pablo Rodriguez-Lopez, Wilton Kort-Kamp, Diego Dalvit Graphene materials have given an impetus to the field of electromagnetic fluctuation interactions, such as Casimir forces. The discovery of unusual distance asymptotics, pronounced thermal effects, and strong dependence on the chemical potential in graphene Casimir interactions have shown new directions for control of this universal force. Recently discovered silicene, a graphene-like material with staggered lattice and significant spin-orbit coupling, offers new opportunities to re-evaluate these unusual Casimir interaction functionalities. Utilizing the Lifshitz formalism we investigate how the spatial dispersion and temperature affect the Casimir interaction in silicene undergoing various topological phase transitions under an applied electric field and laser illumination. This study is facilitated by the comprehensive examination of the conductivity components calculated via the Kubo formalism. We show that the interplay between temperature, spatial dispersion, and topology result in novel features in Casimir interactions involving staggered graphene-like lattices. [Preview Abstract] |
Thursday, March 16, 2017 4:30PM - 4:42PM |
V32.00011: Edge states and electric field effects of zigzag silicene, germanenen and stanene nanoribbons with edge hydrogen terminations Ayami Hattori Silicene, germanene and stanene are novel two dimensional graphene-like materials composed of silicon, germanium and tin atoms. In these materials, quantum spin Hall effects can be observed at experimentally accessible temperature since they have larger spin-orbit coupling than graphene [1]. These materials prefer to construct \textit{sp}$^{\mathrm{3}}$-like hybridized orbitals rather than \textit{sp}$^{2}$ ones [2,3]. Since the structures are crucial for these materials, not only $\pi $ but also $\sigma $ orbitals influence seriously on the energy spectra of edge states [4]. We study edge states controlled by an electric field perpendicular to the zigzag silicene, germanene and stanene nanoribbons (ZSiNRs, ZGeNRs and ZSnNRs) based on a multi-orbital tight-binding model. We show the edge states of ZSiNRs and ZGeNRs remain in the bulk energy gap even if above the critical electric field. However we discuss only ZSnNRs are promising materials of topological quantum field effect transistor from our light calculations. [1] C. -C. Liu, et al., Phys. Rev. Lett. 107, 076802 (2011). [2] K. Takeda and K. Shiraishi, Phys. Rev. B, 50, 14916 (1994). [3] S. Cahangirov, et al., Phys. Rev. Lett. 102, 236804 (2009). [4] A. Hattori, et al., arXiv: 1604.04717 (2016). [Preview Abstract] |
Thursday, March 16, 2017 4:42PM - 4:54PM |
V32.00012: First-Principles DFT Studies of the Vibrational Properties of Germanene Nanoflakes Steven Richardson, Borja Peroparde, Xavier Andrade, Alán Aspuru-Guzik The germanium analogue of graphene, germanene, is a potentially new atomically thin quantum material which theory predicts will possess unique transport and optoelectronic properties. Recently, there have been a number of experimental efforts to successfully grow two-dimensional films of germanene on noble metal substrates using molecular beam epitaxy. In addition to this top-down approach of synthesizing large scale films of germanene, we would like to focus on a bottom-up approach where nanoflakes of germanene could be used as molecular seeds or precursors to grow large films of two-dimensional germanene. A knowledge of their infrared and Raman spectra will be critical for characterizing these germanene nanoflakes in future experiments. In this work we used density-functional theory (DFT) to compute the vibrational spectra of a selected number of lower order germanene nanoflakes (e.g. hexagermabenzene, ${\it germa}$-naphthalene, ${\it germa}$-anthracene, ${\it germa}$-phenanthrene, ${\it germa}$-pyrene, ${\it germa}$-tetracene, and ${\it germa}$-pentacene). Our DFT studies also reveal that these germanene nanoflakes are vibrationally stable with buckling of these molecules from their normal two-dimensional planar forms which exist in graphene nanoflakes. [Preview Abstract] |
Thursday, March 16, 2017 4:54PM - 5:06PM |
V32.00013: Computational design and point defects engineering in two-dimensional silicene and germanene. Yuliang Mao We present first-principles results of a new type hybrid phases composed by buckled germanene with saturated or half-saturated alkali metal atoms adsorption. Our energetics and electronic structure analysis suggests that adsorbed alkali metal atoms (Li, Na, K) can be used as covered adatoms to synthesize germanene-based new phases in two dimensional. Charge transfer is significant between the alkali metal atoms and Ge, indicating the ionic interactions between them. Furthermore, our charge density analysis indicates that covalent component in some extent exists in Ge$_{\mathrm{2}}$X$_{\mathrm{2}}$ and Ge$_{\mathrm{2}}$X$_{\mathrm{1}}$ (X $=$ Li, Na, K) 2D phases, which even leads the complete lithiated germanene into a semiconductor with an energy gap of 0.14 eV. We report that 2D phases of Ge$_{\mathrm{2}}$X$_{\mathrm{1}}$ (X $=$ Li, Na, K) are metallic with weak polarization on the Fermi level and in unoccupied states. We also performed spin-polarized calculations to design the lithium storage material by using the active edges of zigzag silicene nanoribbon. We predict that edge-adsorpion of Li adatoms on zigzag silicene nanoribbon is preferred in energy to form new type lithium storage materials. [Preview Abstract] |
Thursday, March 16, 2017 5:06PM - 5:18PM |
V32.00014: Light element based low dimensional compounds with penta-structure Shunhong Zhang, Xiaoyin Li, Jian Zhou, Qian Wang, Puru Jena Previously we proposed penta-graphene (PG) as a two dimensional carbon structure that is only composed of carbon pentagons. Its novel properties such as negative Poisson's ratio have raised broad interest. Inspired by this study many PG-like light element based low dimensional compounds have been theoretically designed via first principles calculations. Here we present some of such examples. The first one is penta-CN$_{2}$, a chemical analogue of PG, which is characterized by its unexpected high nitrogen content and high in-plane stiffness. It also exhibits an interesting nonsymmorphic symmetry protected band degeneracy at the Brillouin zone edge. We also investigate the chemical derivatives of PG obtained via hydrogenation and halogenation. Such surface functionalization can effectively tune the electronic, mechanical and thermal properties of PG. Finally, we will briefly introduce experimental progress of realization of low dimensional penta-structures. [Preview Abstract] |
Thursday, March 16, 2017 5:18PM - 5:30PM |
V32.00015: A new two-dimensional silicon crystal Kisung Chae, DuckYoung Kim, Young-Woo Son Silicon is one of the most extensively studied materials owing to its significance to the industry and fundamental understanding. There has been progress in searching for a new crystalline bulk phase of silicon with unusual properties. On the other hand, new phases of two-dimensional silicon have not yet been studied as much as the three-dimensional structures, and only a few can be found recently. In this talk, we report a theoretical study on a new series of two-dimensional crystalline silicon with unprecedented structural and electronic properties. The new crystal structures have the outermost layers of perfectly planar honeycomb lattices, sandwiching cubic diamond-like inner layer without coordination defect, implying the inertness of the flat surface. Most of the structures show indirect band gap of which the size decreases with increasing thickness. The new two-dimensional silicon crystals with an inert surface and a variety of electronic properties may play an important role in realizing two-dimensional electronic device of van der Waals heterojunction. [Preview Abstract] |
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