Relevant bibliographies by topics / Natural van der Waals heterostructures

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Academic literature on the topic 'Natural van der Waals heterostructures'

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Published: 6 September 2023

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Journal articles on the topic "Natural van der Waals heterostructures"

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Ray, Kyle, Alexander E. Yore, Tong Mou, Sauraj Jha, Kirby K. H. Smithe, Bin Wang, Eric Pop, and A. K. M. Newaz. "Photoresponse of Natural van der Waals Heterostructures." ACS Nano 11, no. 6 (May 16, 2017): 6024–30. http://dx.doi.org/10.1021/acsnano.7b01918.

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Li, Jie, Lin Du, Jing Huang, Yuan He, Jun Yi, Lili Miao, Chujun Zhao, and Shuangchun Wen. "Passive photonic diodes based on natural van der Waals heterostructures." Nanophotonics 10, no. 2 (November 9, 2020): 927–35. http://dx.doi.org/10.1515/nanoph-2020-0442.

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AbstractVan der Waals heterostructures are composed of stacked atomically thin two-dimensional (2D) crystals to provide unprecedented functionalities and novel physics. Franckeite, a naturally occurring van der Waals heterostructure consisting of superimposed SnS2-like and PbS-like layers alternately, shows intriguing potential in versatile optoelectronic applications. Here, we have prepared the few-layer franckeite via liquid-phase exfoliation method and characterized its third-order nonlinearity and ultrafast dynamics experimentally. We have found that the layered franckeite shows low saturable intensity, large modulation depth and picosecond ultrafast response. We have designed the passive photonic diodes based on the layered franckeite/C60 cascaded film and suspension configuration and found that the passive photonic diodes exhibit stable nonreciprocal transmission of light. The experimental results show the excellent nonlinear optical performance and ultrafast response of the layered franckeite, which may make inroad for the cost effective and reliable high-performance optoelectronic devices.
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Z. Costa, Viviane, Bryce Baker, Hon-Loen Sinn, Addison Miller, K. Watanabe, T. Taniguchi, and Akm Newaz. "Observation of photoluminescence from a natural van der Waals heterostructure." Applied Physics Letters 120, no. 25 (June 20, 2022): 253101. http://dx.doi.org/10.1063/5.0089439.

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van der Waals heterostructures comprised of two-dimensional (2D) materials offer a platform to obtain materials by design with unique electronic properties. Franckeite (Fr) is a naturally occurring van der Waals heterostructure comprised of two distinct alternately stacked semiconducting layers: (i) SnS2 layer and (ii) Pb3SbS4. Though both layers in the heterostructure are semiconductors, the photoluminescence from Franckeite remains elusive. Here, we report the observation of photoluminescence (PL) from Franckeite. We observed two PL peaks at ∼1.97 and ∼2.12 eV at 1.5 K. By varying the temperature from 1.5 to 280 K, we found that the PL peak position blueshifts and the integrated intensity decreases slowly as we increase the temperature. We observed linear dependence of photoluminescence integrated intensity on excitation laser power, indicating that the photoluminescence is originating from free excitons in the SnS2 layer of Fr. By comparing the PL from Fr with the PL from a monolayer MoS2, we determined that the PL quantum efficiency from Fr is an order of magnitude lower than that of a monolayer MoS2. Our study provides a fundamental understanding of the optical behavior in a complex naturally occurring van der Waals heterostructure and may pave an avenue toward developing nanoscale optical and optoelectronic devices with tailored properties.
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Wu, Jiazhen, Fucai Liu, Masato Sasase, Koichiro Ienaga, Yukiko Obata, Ryu Yukawa, Koji Horiba, et al. "Natural van der Waals heterostructural single crystals with both magnetic and topological properties." Science Advances 5, no. 11 (November 2019): eaax9989. http://dx.doi.org/10.1126/sciadv.aax9989.

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Heterostructures having both magnetism and topology are promising materials for the realization of exotic topological quantum states while challenging in synthesis and engineering. Here, we report natural magnetic van der Waals heterostructures of (MnBi2Te4)m(Bi2Te3)n that exhibit controllable magnetic properties while maintaining their topological surface states. The interlayer antiferromagnetic exchange coupling is gradually weakened as the separation of magnetic layers increases, and an anomalous Hall effect that is well coupled with magnetization and shows ferromagnetic hysteresis was observed below 5 K. The obtained homogeneous heterostructure with atomically sharp interface and intrinsic magnetic properties will be an ideal platform for studying the quantum anomalous Hall effect, axion insulator states, and the topological magnetoelectric effect.
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Banik, Ananya, and Kanishka Biswas. "Synthetic Nanosheets of Natural van der Waals Heterostructures." Angewandte Chemie 129, no. 46 (October 6, 2017): 14753–58. http://dx.doi.org/10.1002/ange.201708293.

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Banik, Ananya, and Kanishka Biswas. "Synthetic Nanosheets of Natural van der Waals Heterostructures." Angewandte Chemie International Edition 56, no. 46 (October 6, 2017): 14561–66. http://dx.doi.org/10.1002/anie.201708293.

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Li, Jie, Ke Yang, Lin Du, Jun Yi, Jing Huang, Jinrui Zhang, Yuan He, et al. "Nonlinear Optical Response in Natural van der Waals Heterostructures." Advanced Optical Materials 8, no. 15 (May 7, 2020): 2000382. http://dx.doi.org/10.1002/adom.202000382.

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Bai, Wei, Pengju Li, Sailong Ju, Chong Xiao, Haohao Shi, Sheng Wang, Shengyong Qin, Zhe Sun, and Yi Xie. "Monolayer Behavior of NbS2 in Natural van der Waals Heterostructures." Journal of Physical Chemistry Letters 9, no. 22 (October 23, 2018): 6421–25. http://dx.doi.org/10.1021/acs.jpclett.8b02781.

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Gant, Patricia, Foad Ghasemi, David Maeso, Carmen Munuera, Elena López-Elvira, Riccardo Frisenda, David Pérez De Lara, Gabino Rubio-Bollinger, Mar Garcia-Hernandez, and Andres Castellanos-Gomez. "Optical contrast and refractive index of natural van der Waals heterostructure nanosheets of franckeite." Beilstein Journal of Nanotechnology 8 (November 8, 2017): 2357–62. http://dx.doi.org/10.3762/bjnano.8.235.

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We study mechanically exfoliated nanosheets of franckeite by quantitative optical microscopy. The analysis of transmission-mode and epi-illumination-mode optical microscopy images provides a rapid method to estimate the thickness of the exfoliated flakes at first glance. A quantitative analysis of the optical contrast spectra by means of micro-reflectance allows one to determine the refractive index of franckeite over a broad range of the visible spectrum through a fit of the acquired spectra to a model based on the Fresnel law.
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Varadwaj, Pradeep R., Arpita Varadwaj, Helder M. Marques, and Koichi Yamashita. "Chalcogen Bonding in the Molecular Dimers of WCh2 (Ch = S, Se, Te): On the Basic Understanding of the Local Interfacial and Interlayer Bonding Environment in 2D Layered Tungsten Dichalcogenides." International Journal of Molecular Sciences 23, no. 3 (January 23, 2022): 1263. http://dx.doi.org/10.3390/ijms23031263.

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Layered two-dimensional transition metal dichalcogenides and their heterostructures are of current interest, owing to the diversity of their applications in many areas of materials nanoscience and technologies. With this in mind, we have examined the three molecular dimers of the tungsten dichalcogenide series, (WCh2)2 (Ch = S, Se, Te), using density functional theory to provide insight into which interactions, and their specific characteristics, are responsible for the interfacial/interlayer region in the room temperature 2H phase of WCh2 crystals. Our calculations at various levels of theory suggested that the Te···Te chalcogen bonding in (WTe2)2 is weak, whereas the Se···Se and S···S bonding interactions in (WSe2)2 and (WS2)2, respectively, are of the van der Waals type. The presence and character of Ch···Ch chalcogen bonding interactions in the dimers of (WCh2)2 are examined with a number of theoretical approaches and discussed, including charge-density-based approaches, such as the quantum theory of atoms in molecules, interaction region indicator, independent gradient model, and reduced density gradient non-covalent index approaches. The charge-density-based topological features are shown to be concordant with the results that originate from the extrema of potential on the electrostatic surfaces of WCh2 monomers. A natural bond orbital analysis has enabled us to suggest a number of weak hyperconjugative charge transfer interactions between the interacting monomers that are responsible for the geometry of the (WCh2)2 dimers at equilibrium. In addition to other features, we demonstrate that there is no so-called van der Waals gap between the monolayers in two-dimensional layered transition metal tungsten dichalcogenides, which are gapless, and that the (WCh2)2 dimers may be prototypes for a basic understanding of the physical chemistry of the chemical bonding environments associated with the local interfacial/interlayer regions in layered 2H-WCh2 nanoscale systems.
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Dissertations / Theses on the topic "Natural van der Waals heterostructures"

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Boddison-Chouinard, Justin. "Fabricating van der Waals Heterostructures." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38511.

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The isolation of single layer graphene in 2004 by Geim and Novoselov introduced a method that researchers could extend to other van der Waals materials. Interesting and new properties arise when we reduce a crystal to two dimensions where they are often different from their bulk counterpart. Due to the van der Waals bonding between layers, these single sheets of crystal can be combined and stacked with diferent sheets to create novel materials. With the goal to study the interesting physics associated to these stacks, the focus of this work is on the fabrication and characterization of van der Waals heterostructures. In this work, we first present a brief history of 2D materials, the fabrication of heterostructures, and the various tools used to characterize these materials. We then give a description of the custom-built instrument that was used to assemble various 2D heterostructures followed by the findings associated with the optimization of the cleanliness of the stack's interface and surface. Finally, we discuss the results related to the twisting of adjacent layers of stacked MoS2 and its relation to the interlayer coupling between said layers.
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Mauro, Diego. "Electronic properties of Van der Waals heterostructures." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10565/.

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L’interazione spin-orbita (SOI) nel grafene è attualmente oggetto di intensa ricerca grazie alla recente scoperta di una nuova classe di materiali chiamati isolanti topologici. Questi materiali, la cui esistenza è strettamente legata alla presenza di una forte SOI, sono caratterizzati dall’interessante proprietà di avere un bulk isolante ed allo stesso tempo superfici conduttrici. La scoperta teorica degli isolanti topologici la si deve ad un lavoro nato con l’intento di studiare l’influenza dell’interazione spin-orbita sulle proprietà del grafene. Poichè questa interazione nel grafene è però intrinsecamente troppo piccola, non è mai stato possibile effettuare verifiche sperimentali. Per questa ragione, vari lavori di ricerca hanno recentemente proposto tecniche volte ad aumentare questa interazione. Sebbene alcuni di questi studi abbiano mostrato un effettivo aumento dell’interazione spin-orbita rispetto al piccolo valore intrinseco, sfortunatamente hanno anche evidenziato una consistente riduzione della qualità del grafene. L’obbiettivo che ci si pone in questa tesi è di determinare se sia possibile aumentare l’interazione spin-orbita nel grafene preservandone allo stesso tempo le qualità. La soluzione proposta in questo lavoro si basa sull’utilizzo di due materiali semiconduttori, diselenio di tungsteno WSe2 e solfuro di molibdeno MoS2, utilizzati da substrato su cui sopra verrà posizionato il grafene formando così un’eterostruttura -nota anche di “van der Waal” (vdW)-. Il motivo di questa scelta è dovuto al fatto che questi materiali, appartenenti alla famiglia dei metalli di transizione dicalcogenuri (TMDS), mostrano una struttura reticolare simile a quella del grafene, rendendoli ideali per formare eterostrutture e ancora più importante, presentano una SOI estremamente grande. Sostanzialmente l’idea è quindi di sfruttare questa grande interazione spin-orbita del substrato per indurla nel grafene aumentandone così il suo piccolo valore intrinseco.
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Marsden, Alexander J. "Van der Waals epitaxy in graphene heterostructures." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/77193/.

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Graphene — a two-dimensional sheet of carbon atoms — has surged into recent interest with its host of remarkable properties and its ultimate thinness. However, graphene combined with other materials is starting to attract more attention. These heterostructures can be important for production routes, incorporating graphene into existing technologies, or for modifying its intrinsic properties. This thesis aims to examine the role of van der Waals epitaxy within these heterostructures. First, the graphene-copper interaction during chemical vapour deposition of graphene is investigated. Graphene is found to grow with a mismatch epitaxy of 8 relative to the [001] direction of the Cu(100) surface, despite a mismatch in symmetry and lattice parameter between two. Further, the electronic structure of both graphene and copper is unchanged by the interaction. This highlights the weak interaction between the two, owing to its van der Waals nature. Functionalised graphene is another important heterostructure, and is intensively studied for both graphene production routes and for altering graphene’s properties. Here, it is the change to the homogeneous graphene surface that makes it interesting for van der Waals epitaxy. The effect of functionalisation of graphene with atomic oxygen and nitrogen is presented next. In both cases, only small amounts of functionalisation ( 5 at%) is sufficient to significantly deteriorate the -band structure of the graphene through localisation. For small amounts of nitrogen functionalisation, and greater amounts of oxygen functionalisation, extended topological defects are formed in the graphene lattice. Unlike epoxide oxygen groups, these disruptions to the pristine graphene are found to be irreversible by annealing. Next, the interaction between graphene and the organic semiconducting molecule vanadyl-phthalocyanine (VOPc) is presented. As a result of the van der Waals nature of the graphene surface, VOPc molecules can form crystals microns in size when deposited onto a substrate with an elevated temperature of 155 C; at ambient temperatures, the crystals are only tens of nanometres across. In contrast, the functionalised graphene oxide surface prevents large crystal growth, even at elevated temperatures, because surface functionalities inhibit molecule diffusion. This highlights the importance of graphene as a substrate for molecular crystal growth, even when the growth is not epitaxial. Finally, the supramolecular assembly of trimesic acid (TMA) and terephthalic acid (TPA) is presented. Despite their chemical similarity they display different behaviour as they transition from monolayers to three-dimensional structures: for TMA, the epitaxial chicken wire structure seen at a monolayer templates up through the layers as molecules stack, until a thickness of 20 nm, when random in-plane orientations appear; on the other hand, TPA forms a brickwork structure at the monolayer, which quickly transitions to fibre-like crystals with a bulk structure for the thin films. However, the TPA orientation is still determined by the epitaxy with the graphene substrate, although this is significantly weaker than for TMA.
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Coy, Diaz Horacio. "Preparation and Characterization of Van der Waals Heterostructures." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6212.

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In this dissertation different van der Waals heterostructures such as graphene-MoS2 and MoTe2-MoS2 were prepared and characterized. In the first heterostructure, polycrystalline graphene was synthesized by chemical vapor deposition and transferred on top of MoS2 single crystal. In the second heterostructure, MoTe2 monolayers were deposited on MoS2 by molecular beam epitaxy. Characterization of graphene-MoS2 heterostructures was conducted by spin and angle resolve spectroscopy which showed that the electronic structure of the bulk MoS2 and graphene in this van der Waals heterostructures is modified. For MoS2 underneath the graphene, a band structure renormalization and spin polarization are observed. The band structure of MoS2 is modified because the graphene induces screening which shifts the Г-point ~150 meV to lower binding compared to the sample without graphene. The spin polarization is explained by the dipole arising from band bending which breaks the symmetry at the MoS2 surface. For graphene, the band structure at lower binding energy shows that the Dirac cone remains intact with no significant doping. Instead, away from the Fermi level the formation of several gaps in the pi-band due to hybridization with states from the MoS2 is observed. For the heterostructures made depositing monolayer of MoTe2 on MoS2, the morphology, structure and electronic structure were studied. Two dimensional growth is observed under tellurium rich growth conditions and a substrate temperature of 200 °C but formation of a complete monolayer was not achieved. The obtained MoTe2 monolayer shows a high density of the mirror-twins grain boundaries arranged in a pseudo periodic wagon wheel pattern with a periodicity of ~2.6 nm. These grain boundary are formed due to Te-deficiency during the growth. The defect states from these domain boundary pin the Fermi level in MoTe2 and thus determine the band alignment in the MoTe2-MoS2 heterostructures.
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Ma, Qiong Ph D. Massachusetts Institute of Technology. "Optoelectronics of graphene-based Van der Waals heterostructures." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104523.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Research on van der Waals (vdW) materials (homo- or hetero-) is a rapidly emerging field in condensed matter physics. They are layered structures with strong chemical bonding within layers and relatively weak van der Waals force to combine layers together. This unique layer-bylayer nature makes it easy to exfoliate layers out and at the same time to re-assemble in arbitrary sequences with different combinations. The versatility, flexibility, and relatively low cost of production make the scientific community enthusiastic about their future. In this thesis, I investigate the fundamental physical processes of light-matter interactions in these layered structures, including graphene, boron nitride, transition metal dichalcogenides and heterostructures formed from these materials. My research involves state-of-the-art nanoscale fabrication and microscale photocurrent spectroscopy and imaging. In Chapter 1, 1 will briefly discuss basic physical properties of the vdW materials involved in this thesis and introduce the main nanofabrication and measurement techniques. Chapter 2-4 are about hot electron dynamics and electron-phonon coupling in intrinsic graphene systems, among which Chapter 2 is focusing on the generation mechanism of the photocurrent at the p-n interface, which is demonstrated to have a photothermoelectric origin. This indicates a weak electron-phonon coupling strength in graphene. Chapter 3 is a direct experimental follow-up of the work in Chapter 2 and reveals the dominant electron-phonon coupling mechanism at different temperature and doping regimes. In Chapter 4, I present the observation of anomalous geometric photocurrent patterns in various devices at the charge neutral point. The spatial pattern can be understood as a local photo-generated current near edges being collected by remote electrodes. The anomalous behavior as functions of change density and temperature indicates an interesting regime of energy and charge dynamics. In Chapter 5 and 6, 1 will show the photoresponse of graphene-BN heterostuctures. In graphene-BN stack directly on SiO₂, we observed strong photo-induced doping phenomenon, which can be understood as charge transfer from graphene across BN and eventually trapped at the interface between BN and SiO₂. By inserting another layer of graphene between BN and SiO₂ , we can measure an electrical current after photoexcitation due to such charge transfer. We further studied the competition between this vertical charge transfer and in-plane carrier-carrier scattering in different regimes. In Chapter 7, I will briefly summarize collaborated work with Prof. Dimitri Basov's group on near-field imaging of surface polariton in two-dimensional materials. This technique provides a complementary tool to examine the intriguing light-matter interaction (for large momentum excitations) in low-dimensional materials. Chapter 8 is the outlook, from my own point of view, what more can be done following this thesis.
by Qiong Ma.
Ph. D.
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Khestanova, Ekaterina. "Van der Waals heterostructures : fabrication, mechanical and electronic properties." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/van-der-waals-heterostructures-fabrication-mechanical-and-electronic-properties(047ce24b-7a58-4192-845d-54c7506f179f).html.

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The fast progress in the exploration of 2D materials such as graphene became possible due to development of fabrication techniques that allowed these materials to be protected from e.g. undesirable doping and gave rise to new functionalities realized within van der Waals heterostructures. Attracted by van der Waals interaction the constituent layers of such heterostructures preserve their exceptional electronic quality and for example in graphene allow for high electron mobility to be achieved. However, the studies of atomically thin layers such as NbSe2 that exhibit metallic behavior have been impeded by their reactivity and hence oxidation during exposure to ambient or oxidizing agents such as solvents. In this thesis, the existing heterostructure assembly technique was improved by the introduction of exfoliation and re-stacking by a fully motorized system placed in an inert atmosphere. This approach allowed us to overcome the problem of environmental degradation and create Hall bars and planar tunnel junctions from atomically thin superconducting NbSe2. Furthermore, this versatile approach allowed us to study the thickness dependence of the normal and superconducting state transport properties of NbSe2, uncovering the reduction of the superconducting energy gap and transition temperature in the thinnest samples. On the other hand, 2D materials being just 1-3 atoms thick represent an ultimate example of a membrane - thin but laterally extended object. Consisting of such atomically thin membranes the van der Waals heterostructures can be used for purposes other than the studies of electronic transport. In this work, ubiquitous bubbles occurring during van der Waals heterostructure assembly are employed as a tool to explore 2D materials' mechanical properties and mutual adhesion. This allowed us to measure Young's modulus of graphene and other 2D materials under 1-2% strain and deduce the internal pressure that can reach up to 1 GPa in sub-nanometer size bubbles.
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Yu, Geliang. "Transport properties of graphene based van der Waals heterostructures." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/transport-properties-of-graphene-based-van-der-waals-heterostructures(5cbb782f-4d49-42da-a05e-15b26606e263).html.

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In the past few years, led by graphene, a large variety of two dimensional (2D) materials have been discovered to exhibit astonishing properties. By assembling 2D materials with different designs, we are able to construct novel artificial van der Waals (vdW) heterostructures to explore new fundamental physics and potential applications for future technology. This thesis describes several novel vdW heterostructures and their fundamental properties. At the beginning, the basic properties of some 2D materials and assembled vdW heterostructures are introduced, together with the fabrication procedure and transport measurement setups. Then the graphene based capacitors on hBN (hexagonal Boron Nitride) substrate are studied, where quantum capacitance measurements are applied to determine the density of states and many body effects. Meanwhile, quantum capacitance measurement is also used to search for alternative substrates to hBN which allow graphene to exhibit micrometer-scale ballistic transport. We found that graphene placed on top of MoS2 and TaS2 show comparable mobilities up to 60,000cm2/Vs. After that, the graphene/hBN superlattices are studied. With a Hall bar structure based on the superlattices, we find that new Dirac minibands appear away from the main Dirac cone with pronounced peaks in the resistivity and are accompanied by reversal of the Hall effects. With the capacitive structure based on the superlattices, quantum capacitance measurement is used to directly probe the density states in the graphene/hBN superlattices, and we observe a clear replica spectrum, the Hofstadter-butterfly fan diagram, together with the suppression of quantum Hall Ferromagnetism. In the final part, we report on the existence of the valley current in the graphene/hBN superlattice structure. The topological current originating from graphene’s two valleys flows in opposite directions due to the broken inversion symmetry in the graphene/hBN superlattice, meaning an open band gap in graphene.
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Tomarken, Spencer Louis. "Thermodynamic and tunneling measurements of van der Waals heterostructures." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123567.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 201-212).
In certain electronic systems, strong Coulomb interactions between electrons can favor novel electronic phases that are difficult to anticipate theoretically. Accessing fundamental quantities such as the density of states in these platforms is crucial to their analysis. In this thesis, I explore the application of two measurement techniques towards this goal: capacitance measurements that probe the thermodynamic ground state of an electronic system and planar tunneling measurements that access its quasiparticle excitation spectrum. Both techniques were applied to van der Waals materials, a class of crystals composed of layered atomic sheets with weak interplane bonding which permits the isolation of single and few-layer sheets that can be manually assembled into heterostructures. Capacitance measurements were performed on a material system commonly known as magic-angle twisted bilayer graphene (MATBG).
When two monolayers of graphene, a single sheet of graphite, are stacked on top of one another with a relative twist between their crystal axes, the resultant band structure is substantially modified from the cases of both monolayer graphene and Bernal-stacked (non-twisted) bilayer graphene. At certain magic angles, the low energy bands become extremely flat, quenching the electronic kinetic energy and allowing strong electron-electron interactions to become relevant. Exotic insulating and superconducting phases have been observed using conventional transport measurements. By accessing the thermodynamic density of states of MATBG, we estimate its low energy bandwidth, Fermi velocity, and interaction-driven energy gaps. Time-domain planar tunneling was performed on a heterostructure that consisted of monolayer graphene and hexagonal boron nitride (serving as the dielectric and tunnel barrier) sandwiched between a graphite tunneling probe and metal gate.
Tunneling currents were induced by applying a sudden voltage pulse across the full parallel plate structure. The lack of in-plane charge motion allowed access to the tunneling density of states even when the heterostructure was electrically insulating in the quantum Hall regime. These measurements represent the first application of time-domain planar tunneling to the van der Waals class of materials, an important step in extending the technique to new material platforms.
by Spencer Louis Tomarken.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Physics
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Luo, Yuanhong Ph D. Massachusetts Institute of Technology. "Twist angle physics in graphene based van der Waals heterostructures." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119050.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged student-submitted from PDF version of thesis.
Includes bibliographical references (pages 121-131).
In this thesis, I present my experimental work on twisted bilayer graphene, a van der Waals heterostructure consisting of two graphene sheets stack on top of each other. In particular, the twist angle is a new degree of freedom in this system, and has an important effect in the determination of its transport properties. The work presented will explore the twist-dependent physics in two regimes: the large twist angle and small twist angle regimes. In the large-twist angle limit, the two sheets have little interlayer interactions and are strongly decoupled, allowing us to put independent quantum Hall edge modes in both layers. We study the edge state interactions in this system, culminating in the formation of a quantum spin Hall state in twisted bilayer graphene. In the small twist angle limit, interlayer interactions are strong and the layers are strongly hybridized. Additionally, a new long-range moiré phenomenon emerges, and we study the effects of the interplay between moiré physics and interlayer interactions on its transport properties.
by Yuanhong Luo.
Ph. D.
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Yankowitz, Matthew Abraham. "Local Probe Spectroscopy of Two-Dimensional van der Waals Heterostructures." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/594649.

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A large family of materials, collectively known as "van der Waals materials," have attracted enormous research attention over the past decade following the realization that they could be isolated into individual crystalline monolayers, with charge carriers behaving effectively two-dimensionally. More recently, an even larger class of composite materials has been realized, made possible by combining the isolated atomic layers of different materials into "van der Waals heterostructures," which can exhibit electronic and optical behaviors not observed in the parent materials alone. This thesis describes efforts to characterize the atomic-scale structural and electronic properties of these van der Waals materials and heterostructures through scanning tunneling microscopy measurements. The majority of this work addresses the properties of monolayer and few-layer graphene, whose charge carriers are described by massless and massive chiral Dirac Hamiltonians, respectively. In heterostructures with hexagonal boron nitride, an insulating isomorph of graphene, we observe electronic interference patterns between the two materials which depend on their relative rotation. As a result, replica Dirac cones are formed in the valence and conduction bands of graphene, with their energy tuned by the rotation. Further, we are able to dynamically drag the graphene lattice in these heterostructures, owing to an interaction between the scanning probe tip and the domain walls formed by the electronic interference pattern. Similar dragging is observed in domain walls of trilayer graphene, whose electronic properties are found to depend on the stacking configuration of the three layers. Scanning tunneling spectroscopy provides a direct method for visualizing the scattering pathways of electrons in these materials. By analyzing the scattering, we can directly infer properties of the band structures and local environments of these heterostructures. In bilayer graphene, we map the electrically field-tunable band gap and extract electronic hopping parameters. In WSe₂, a semiconducting transition metal dichalcogenide, we observe spin and layer polarizations of the charge carriers, representing a coupling of the spin, valley and layer degrees of freedom.
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Books on the topic "Natural van der Waals heterostructures"

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Holwill, Matthew. Nanomechanics in van der Waals Heterostructures. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9.

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Finney, Nathan Robert. Symmetry engineering via angular control of layered van der Waals heterostructures. [New York, N.Y.?]: [publisher not identified], 2021.

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Holwill, Matthew. Nanomechanics in van der Waals Heterostructures. Springer, 2019.

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2D Materials and Van der Waals Heterostructures. MDPI, 2020. http://dx.doi.org/10.3390/books978-3-03928-769-7.

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Zhang, Zheng, and Yue Zhang. Van der Waals Heterostructures: Fabrications, Properties and Applications. Wiley & Sons, Incorporated, John, 2022.

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Zhang, Zheng, and Yue Zhang. Van der Waals Heterostructures: Fabrications, Properties and Applications. Wiley & Sons, Limited, John, 2022.

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Zhang, Zheng, and Yue Zhang. Van der Waals Heterostructures: Fabrications, Properties and Applications. Wiley & Sons, Incorporated, John, 2022.

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Zhang, Zheng, and Yue Zhang. Van der Waals Heterostructures: Fabrications, Properties and Applications. Wiley & Sons, Incorporated, John, 2022.

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Book chapters on the topic "Natural van der Waals heterostructures"

1

Holwill, Matthew. "van der Waals Heterostructures." In Nanomechanics in van der Waals Heterostructures, 19–31. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_3.

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Lui, C. H. "Raman Spectroscopy of van der Waals Heterostructures." In Raman Spectroscopy of Two-Dimensional Materials, 81–98. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1828-3_4.

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Holwill, Matthew. "Introduction." In Nanomechanics in van der Waals Heterostructures, 1–6. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_1.

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Holwill, Matthew. "Properties of Two-Dimensional Materials." In Nanomechanics in van der Waals Heterostructures, 7–17. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_2.

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Holwill, Matthew. "Fabrication and Characterisation Techniques." In Nanomechanics in van der Waals Heterostructures, 33–51. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_4.

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Holwill, Matthew. "Studying Superlattice Kinks via Electronic Transport." In Nanomechanics in van der Waals Heterostructures, 53–70. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_5.

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Holwill, Matthew. "Atomic Force Microscopy Studies of Superlattice Kinks." In Nanomechanics in van der Waals Heterostructures, 71–83. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_6.

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Holwill, Matthew. "Additional Work." In Nanomechanics in van der Waals Heterostructures, 85–91. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_7.

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Holwill, Matthew. "Conclusions and Future Work." In Nanomechanics in van der Waals Heterostructures, 93–94. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-18529-9_8.

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Roy, Kallol. "Photoresponse in Graphene-on-MoS$$_2$$ Heterostructures." In Optoelectronic Properties of Graphene-Based van der Waals Hybrids, 141–56. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-59627-9_6.

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Conference papers on the topic "Natural van der Waals heterostructures"

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Heinz, Tony F. "Optical Properties of van der Waals Heterostructures." In Laser Science. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/ls.2015.lw4h.1.

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Roy, T., M. Tosun, M. Amani, D. H. Lien, D. Kiriya, P. Zhao, S. Desai, A. Sachid, S. R. Madhvapathy, and A. Javey. "Van der Waals heterostructures for tunnel transistors." In 2015 Fourth Berkeley Symposium on Energy Efficient Electronic Systems (E3S). IEEE, 2015. http://dx.doi.org/10.1109/e3s.2015.7336791.

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Caruntu, Dumitru I., and Le Luo. "Reduced Order Model of CNT Cantilever Resonators Under AC Voltage Near Half Natural Frequency." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-85968.

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This paper deals with electrostatically actuated Carbon Nano-Tubes (CNT) cantilevers using Reduced Order Model method. There are three kinds of forces acting on the CNT cantilever: electrostatic, elastostatic, and van der Waals. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forceselectrostatic and van der Waals are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT undergoes nonlinear parametric dynamics. The Method of Multiple Scales (MMS), Reduced Order Model (ROM) and AUTO are used to investigate the system under soft excitations and/or weak nonlinearities. The frequency-amplitude and frequency-phase behaviors are found in the case of resonance near half natural frequency.
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Hashemi, Daniel, Stefan C. Badescu, Michael Snure, and Michael Snure. "Band Alignment in Van der Waals Phosphorous Heterostructures." In THE 3rd INTERNATIONAL CONFERENCE ON THEORETICAL AND APPLIED NANOSCIENCE AND NANOTECHNOLOGY. Avestia Publishing, 2019. http://dx.doi.org/10.11159/tann19.130.

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Plochocka, Paulina. "Excitons in MoS2/MoSe2 Van der Waals heterostructures." In nanoGe Fall Meeting 2019. València: Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.ngfm.2019.443.

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Basov, Dmitri N. "Nano-photonic Phenomena in van der Waals heterostructures." In CLEO: QELS_Fundamental Science. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/cleo_qels.2015.ftu1e.1.

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Plochocka, Paulina. "Excitons in MoS2/MoSe2 Van der Waals heterostructures." In nanoGe Fall Meeting 2019. València: Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.nfm.2019.443.

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Cheng, Beitong, Yong Zhou, Ruomei Jiang, Xule Wang, Shuai Huang, Xingyong Huang, Wei Zhang, Qian Dai, and Hai-Zhi Song. "Graphene-Sandwiched Van der Waals Heterostructures for Photodetectors." In 2023 Photonics & Electromagnetics Research Symposium (PIERS). IEEE, 2023. http://dx.doi.org/10.1109/piers59004.2023.10221375.

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Caruntu, Dumitru I., and Le Luo. "CNT Cantilevers Under Soft AC Actuation of Frequency Near Half Natural Frequency for Bio-Sensing Applications." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-70324.

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This paper deals with electrostatically actuated Carbon Nano-Tubes (CNT) cantilevers for bio-sensing applications. Four forces act on the CNT cantilever, namely electrostatic, elastostatic, van der Waals, and damping. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forces electrostatic and van der Waals are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT undergoes nonlinear parametric dynamics. The method of multiple scales (MMS) is used to investigate the system under soft excitations and/or weak nonlinearities. The frequency-amplitude and frequency-phase behavior are reported. The CNT bio-sensor is to be used for mass detection applications.
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Mockensturm, Eric, and Arash Mahdavi. "Van Der Waal’s Elastica." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82991.

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Experimental investigations of carbon nanotubes have revealed that they can collapse into nanoribbons that have a dumb-bell shape cross-section. Due to the extreme exibility of single-atom thick graphene sheets, if the tube is large enough self-induced Van der Waals forces acting on the at surfaces of the ribbon will be large enough to hold the nanotube in the collapsed (ribbon) configuration. Energetically, the additional strain (bending) energy stored in the collapsed state is offset by the decrease in energy of the Van der Waals interactions. Because Van der Waals forces are short ranged, one nds that tubes of great enough diameter are bistable. Here we investigate the natural of this bistability by investigating how the energy stored in the tube changes as it is compressed by at rigid indenters of various widths. The nanotube is assumed to deform uniformly along its length and the cross-section is modeled using inextensible, non-linear beam theory (Euler’s Elastica). We nd that the in ated (tube) conguration is always stable but that the energy barrier against decreases with increasing tube radius. Additionally, the energy difference between the in ated and collapsed states decreases nearly linear with increasing radius and for tubes with radius greater than 26 A the collapsed state is energetically favored.
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Reports on the topic "Natural van der Waals heterostructures"

1

Kim, Philip. Nano Electronics on Atomically Controlled van der Waals Quantum Heterostructures. Fort Belvoir, VA: Defense Technical Information Center, March 2015. http://dx.doi.org/10.21236/ada616377.

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