Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session A56: Carbon Nanotubes and Strain in 2D MaterialsRecordings Available
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Sponsoring Units: DCMP Chair: Steven Disseler, MIT Lincoln Lab Room: Hyatt Regency Hotel -Burnham |
Monday, March 14, 2022 8:00AM - 8:12AM Withdrawn |
A56.00001: Twisted double-walled carbon nanotubes: A pathway to strongly correlated phases in 1D moiré superlattices Ammon Fischer, Lennart Klebl, Dante M Kennes, Peizhe Tang After the breakthrough in twisted 2D van der Waals materials led by graphene multilayer systems and strongly spin-orbit coupled transition metal dichalcogenides (TMDs), little attention was given to the construction of 1D moiré superlattices [1,2]. Based on first-principle calculations, we demonstrate how 1D moiré superlattices can emerge in twisted double-walled carbon nanotubes (CNT) and that quasi one-dimensional flat bands are formed as a function of twist-angle. Including atomistic interaction effects [3], these flat electronic bands give rise to a variety of correlated phases, including Mott insulating and Luttinger-Liquid phases that we investigate using atomistic fRG and numerical exact density renormalization group (DMRG) methods. Based on our findings, we propose twisted CNTs as an unexplored platform to observe and experimentally control quasi 1D correlated physics. |
Monday, March 14, 2022 8:12AM - 8:24AM |
A56.00002: Electronic transport in ultrahigh-conductivity aligned carbon nanotube assemblies Natsumi Komatsu, Nicolas Marquez Peraca, Xinwei Li, Oliver S Dewey, Lauren W Taylor, Ali Mojibpour, Geoff Wehmeyer, Matteo Pasquali, Matthew Foster, Junichiro Kono Macroscopic assemblies of aligned carbon nanotubes (CNTs) with ultrahigh conductivity (> 10 MS/m) have recently emerged. They are promising for replacing copper- or aluminum-based electrical cables, but further conductivity improvement requires a microscopic understanding of electronic transport processes in CNT assemblies. In particular, it is of great importance to elucidate the roles of disorder, doping, and electron-electron interactions in determining the conductivity. Here, we describe our temperature- and magnetic field-dependent conductivity measurements on aligned CNT fibers and bundles produced by the solution spinning method. We observed a metallic behavior in a wide temperature range (30–300 K), i.e., conductivity monotonically increasing with decreasing temperature. At low temperatures (< 50 K), strongly temperature-dependent negative magnetoresistance appeared, a hallmark of weak localization, suggesting quantum coherent transport. We determined the dimensionality and coherence lengths of carriers via analysis of the weak localization behavior. In addition to macroscopic CNT fibers with diameters of ∼10 μm, we also conducted conductivity measurements on individual crystalline CNT bundles (with diameters ∼ 50 nm and lengths ∼ 30 μm) that constitute the fibers. |
Monday, March 14, 2022 8:24AM - 8:36AM |
A56.00003: Carbon Nanotubes Junction Conductance mechanism: Electronic or Phonon-Assisted? Davoud Adinehloo, Weilu Gao, Ali Mojibpour, Junichiro Kono, Vasili Perebeinos We report the transport properties of single-wall carbon nanotubes (SWCNTs) films theoretically and experimentally. Using the perturbation theory within the tight-binding model approach, we have revealed that the electronic SWCNT junction conductance of the atomically relaxed structure is almost an order of magnitude larger than that in the unrelaxed structure. We demonstrate that the phonon-assisted junction conductance is commensurate to the electronic conductance at room temperature, and it plays a crucial role in the observed temperature dependence. Furthermore, we address the dependence of junction conductance on the angle between the SWCNTs, twist angle and sliding shift of the SWCNTs, the Fermi energy, and the applied bias voltage between SWCNTs. Our calculations perfectly match the experimentally measured temperature conductance. |
Monday, March 14, 2022 8:36AM - 8:48AM |
A56.00004: Hall effect in ionic liquid-gated single-wall carbon nanotube films Yohei Yomogida, Kazuhiro Yanagi, Kanako Horiuchi, Junichiro Kono, Natsumi Komatsu, Weilu Gao, Kan Ueji, Yota Ichinose, Hiroyuki Nishidome The presence of hopping carriers and grain boundaries can sometimes lead to anomalous carrier types and density overestimation in Hall-effect measurements. Previous Hall-effect studies on carbon nanotube films reported unreasonably large carrier densities without independent assessments of the carrier types and densities. Here, we have systematically investigated the validity of Hall-effect results for a series of metallic, semiconducting, and metal-semiconductor-mixed single-wall carbon nanotube films. With carrier densities controlled through applied gate voltages, we were able to observe the Hall effect both in the n- and p-type regions, detecting opposite signs in the Hall coefficient. By comparing the obtained carrier types and densities against values derived from simultaneous field-effect-transistor measurements, we found that, while the Hall carrier types were always correct, the Hall carrier densities were overestimated by up to four orders of magnitude. This significant overestimation indicates that thin films of one-dimensional SWCNTs are quite different from conventional hopping transport systems. |
Monday, March 14, 2022 8:48AM - 9:00AM |
A56.00005: First-principles Study of the Optical and Spin Properties of sp3-doped (6,5) Single-Walled Carbon Nanotubes Kasidet Jing Trerayapiwat, Jia-Shiang Chen, Xuedan Ma, Sahar Sharifzadeh Single-walled carbon nanotubes (SWCNTs) doped with sp3 defects are a promising class of optoelectronic materials with bright tunable photoluminescence and demonstrated single-photon emission. We apply first-principles theory in combination with experimental studies to understand the optoelectronic and spin properties of sp3-defective (6,5) SWCNT containing a single unpaired spin. Density functional theory studies indicate that this unpaired spin localizes around the defect site and leads to an in-gap dispersionless state in the bandstructure of the SWCNT. Furthermore, many-body perturbation theory within the GW/BSE approximation predicts strong excitonic effects with an exciton binding energy of ~ 1 eV for both pristine and sp3-defective (6,5) SWCNT. Additionally, we simulate dephasing of the localized spin by considering spin-bath interactions as the main source of decoherence. We apply the cluster correlation expansion method with a pure-dephasing spin Hamiltonian to doped SWCNT in presence of solvent molecules at near 0 K and estimate the magnitude of the decoherence time (T2), in good agreement with experiment. |
Monday, March 14, 2022 9:00AM - 9:12AM |
A56.00006: Coupling Near-Infrared Emission from Semiconducting Single-Walled Carbon Nanotubes to Optical Microcavities Jia-Shiang Chen, Anushka Dasgupta, Ruggero Emmanuele, Darien Morrow, Tobin J Marks, Mark C Hersam, Xuedan Ma Semiconducting single-walled carbon nanotubes (SWCNTs) possess excellent photostability, conductivity, and natural compatibility with nano-/macro-fabrication techniques, making them promising candidates for optoelectronic applications. In particular, their diameter- and chirality-tunable optical transitions at near-infrared wavelengths render them well suited for high-speed optical communication and biomedical imaging applications. Recent demonstrations of chemical modification-induced molecular defects on SWCNT provide another promising avenue for tuning their wavelength coverage further. In this work, we integrate pristine and chemically functionalized SWCNTs into photonic microcavities. By optimizing the cavity-SWCNT coupling geometry, Purcell effect-induced photoluminescence enhancement can be obtained. Compared to pristine SWCNTs, those functionalized with molecular defects exhibit superior emission properties. The generation of stimulated emission in the cavity-SWCNT systems is also investigated through pump-power dependent spectroscopic measurements. This work suggests that due to the natural compatibility of the SWCNTs with photonic structures, local photonic density modification could be an effective approach for optimizing the emission properties of the SWCNTs. |
Monday, March 14, 2022 9:12AM - 9:24AM |
A56.00007: Computing Young's Modulus and Wall Thickness of Single-Walled Carbon Nanotubes with Atomistic Molecular Dynamics Simulations Tabassum Ahmed, Carl Chalk, Gary D Seidel, Shengfeng Cheng All-atom molecular dynamics simulations are used to study in detail the behavior of several single-walled CNTs of different radii, lengths, and chirality under stretching and bending deformations, realized by imposing appropriate boundary conditions on the CNTs. The simulation results reveal unique scaling properties of the stretching and bending stiffness with respect to the CNT radius and length, which indicate that a single-walled CNT is best modeled as a thin cylindrical shell with a cross-sectional radius equal to the CNT radius and a constant wall thickness much smaller than the CNT radius and the separation of adjacent graphene planes in a graphite. The value of the surface Young's modulus is found to be roughly the same for all the single-walled CNTs simulated. By studying the thermal fluctuations of carbon atoms on the CNT wall, the wall thickness is determined to be about 0.45 Å for all the CNTs studied and correspondingly, Young's modulus is estimated to be about 8.78 TPa for these CNTs, irrespective of CNT radius and chirality. |
Monday, March 14, 2022 9:24AM - 9:36AM |
A56.00008: Tailoring plasmons excitations in α − T3 armchair nanoribbons Paula Fekete, Andrii Iurov, Liubov Zhemchuzhna, Godfrey A Gumbs, Danhong Huang, Farhana Anwar, Dipendra Dahal, Nicholas Weekes We have investigated finite-width alpha-T3 nanoribbons with armchair type of edge termination and have numerically obtained their energy dispersion, electronic states, wavefunctions, dynamical polarization function, and plasmon excitations. The plasmon dispersions obtained are mainly determined by the energy bandgap which depends on the number of atomic rows across the nanoribbon. We have also investigated the Landau damping of such plasmons and their dependence on the nanoribbon geometry and resulting energy bandgap, as well as on the relative hopping parameter α of the α−T3 lattice. |
Monday, March 14, 2022 9:36AM - 9:48AM |
A56.00009: Theory of Strain in Monolayer Transition Metal Dichalcogenides: Electronic Structure and Spin/Orbital Hall Effects in MoS2 PRATIK K SAHU, Sashi S Satpathy Strain has emerged as an important tool to control the electronic properties of two-dimensional monolayer materials such as graphene and the transition-metal dichalcogenides (TMD). One of the interesting aspects of the TMDs such as the MoS2 is the presence of orbital moments at the valley points of the Brillouin zone, which leads to many interesting phenomena such as the orbital Hall effect. Here we present a systematic theory of the strain modification of the electronic structure and the orbital and spin Hall effects under general strain condition in the TMDs. We adopt an approach for the electronic structure different from the earlier works, which leads to a simpler model Hamiltonian for the valley points under strain condition. The strain Hamiltonian is validated by comparing with the results of the density functional theory (DFT). Furthermore, using DFT calculations, the hamiltonian parameters as well as the spin and orbital Hall conductivities (SHC/OHC) are computed for MoS2, which is a typical member of the semiconducting TMDs. The OHC remains strong even under the strain condition, while the SHC continues to remain relatively small, making the TMDs excellent candidate materials for the observation of the OHE, both with or without strain |
Monday, March 14, 2022 9:48AM - 10:00AM |
A56.00010: Flexoelectricity and deformation potential in bulk transition metal dichalcogenides Colin C Gordon Using first-principles approaches based on density functional perturbation theory, we calculate the properties of bulk layered transition-metal dichalcogenides (TMDCs) under the applications of strain gradients. We determine the full flexoelectric tensor, demonstrating the unique properties of such anisotropic systems, and trends with metal and chalcogenide species. In addition, we quantify the role of electronic and ionic contributions, and find that the electronic, clamped-ion contributions are dominant in these materials. To make a direct comparison with experimental observables, we use our flexoelectric coefficients to determine absolute band deformation potentials. Finally, we obtain physical intuition of these results via comparison to hexagonal Boron Nitride and a rigid atom/layer model. |
Monday, March 14, 2022 10:00AM - 10:12AM |
A56.00011: Band gap renormalization in doped transition-metal dichalcogenide heterostructures Linghan Zhu, Xiaobo Lu, Li Yang Transition-metal dichalcogenide (TMD) heterostructures have attracted broad interests as a playground for studying the light-matter interactions and valleytronics in low-dimensional semiconductors. Meanwhile, the carrier density in two-dimensional systems can be conveniently tuned by external gates, thus providing a controlling knob for manipulating their electronic properties. In this work, we employ the first-principles many-body perturbation theory to study the band gap renormalization in carrier-doped TMD heterobilayers. Because of the coupling between the carrier plasmon and quasiparticle excitations, a significant band gap renormalization of a few hundreds of meV is predicted. This band-gap renormalization further significantly affects the band alignment. Our work provides a guidance for experiments on band gap engineering in van der Waals heterostructures. |
Monday, March 14, 2022 10:12AM - 10:24AM |
A56.00012: Mechanical fracture behavior of defective MoS2 monolayer Yun-Peng Wang, Gang Wang, Songge Li, Qishuo Yang, Daiyue Li, Sokrates T Pantelides, Junhao Lin The mechanical properties, including the strength and toughness, of two-dimensional transition-metal chalcogenides play a major role in applications such as flexible electronic devices. In this work, we studied atomic vacancies induced by helium and gallium-ion beams and their effects on mechanical properties of suspended MoS2 monolayers. Atomic-force microscopy (AFM) tests prove that S and MoSx point defects reduce the stiffness but enhance the fracture toughness of MoS2 monolayers. The deflection and bifurcation of cracks and the atomic structure near the crack edges are revealed by scanning-transmission-electron-microscope (STEM) images. Molecular-dynamics simulations based on classical force fields reproduce the microscopic features observed in experiments. MD simulations further predict that defective MoS2 monolayers remain as brittle as pristine ones. The calculated energy release rate is higher in the presence of point defects, which explains the enhancement of fracture toughness as observed in experiments. |
Monday, March 14, 2022 10:24AM - 10:36AM |
A56.00013: Tunable Single-Atomic Charges on a Cleaved Intercalated Transition Metal Dichalcogenide, Co1/3NbS2 Seongjoon Lim, Shangke Pan, Kefeng Wang, Alexey V Ushakov, Ekaterina V Sukhanova, Zakhar I Popov, Dmitry G Kvashnin, Sergey V Streltsov, Sang-Wook Cheong Manipulating the charge state of an individual atom and arranging the charge-modified atoms in a desired manner can provide an ideal platform for the simulation and understanding of atomic charge interactions and the exploitation for atomic-scale devices. Ever since the first demonstration of charge manipulation from a single gold atom deposited on thin insulating layer using scanning tunneling microscopy (STM) probe, charge manipulation of atoms/molecules deposited by evaporation techniques have been established as a toolkit to explore atomic charging-related phenomena. We demonstrate that such a charge state control is possible for intercalant ions exposed on a surface after cleaving/exfoliation of intercalated layered material without any evaporation technique. After cleaving of Co-intercalated NbS2, each Co ion left on the surface can maintain a metastable charge state manipulated by voltage pulse from STM probe despite the direct contact with the metallic NbS2. Density functional theory calculation confirms that this unexpected metastable charge state is possible by the limited Co and Nb a1g orbital hybridization due to the modified crystal field at the surface. We anticipate that this could be a new step towards realizing single-atom-level electronics/spintronics in 2D material. |
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