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Gotowa bibliografia na temat „Topological surface states”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "Topological surface states"

Guo, Yuning, Matheus Rosa i Massimo Ruzzene. "Symmetry-enforced gapless surface states in three-dimensional acoustic gyroid structures". Journal of the Acoustical Society of America 151, nr 4 (kwiecień 2022): A97. http://dx.doi.org/10.1121/10.0010772.

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The discovery of topological gapless phases challenges the perception that topological features necessarily require a bandgap, expanding the understanding of topological phases of matter in various realms including electric, photonic, and phononic systems. The progress on 3D topological gapless states in elastic and acoustic systems is still in its early stages of formulation and design. We here investigate 3D acoustic gyroid crystals supporting symmetry-enforced gapless surface states in minimal surface-based structures. The inherent chirality and morphology of gyroid surfaces enable the implementation of 3D acoustic crystals hosting symmetry-enforced Dirac points and topologically gapless surface states. The associated fourfold degeneracy is protected by the nonsymmorphic space group featuring a combination of screw symmetry and glide reflections. The presence of gapless surface arcs relies on band structure calculations conducted using finite element simulations, while preliminary experimental results on additively manufactured samples validate their occurrence in the proposed gyroid surfaces. With the continuous development in additive manufacturing techniques, the presented surface-based framework provides a platform to explore a variety of topological wave physics phenomena in 3D load-bearing, continuum materials of potential engineering relevance, among which superior acoustic absorption may be particularly promising.

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Ovchinnikov, Yu N. "Topological Insulator: Surface Localized States". Journal of Superconductivity and Novel Magnetism 32, nr 5 (10.08.2018): 1327–31. http://dx.doi.org/10.1007/s10948-018-4827-0.

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Hsu, Chuang-Han, Xiaoting Zhou, Tay-Rong Chang, Qiong Ma, Nuh Gedik, Arun Bansil, Su-Yang Xu, Hsin Lin i Liang Fu. "Topology on a new facet of bismuth". Proceedings of the National Academy of Sciences 116, nr 27 (13.06.2019): 13255–59. http://dx.doi.org/10.1073/pnas.1900527116.

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Bismuth-based materials have been instrumental in the development of topological physics, even though bulk bismuth itself has been long thought to be topologically trivial. A recent study has, however, shown that bismuth is in fact a higher-order topological insulator featuring one-dimensional (1D) topological hinge states protected by threefold rotational and inversion symmetries. In this paper, we uncover another hidden facet of the band topology of bismuth by showing that bismuth is also a first-order topological crystalline insulator protected by a twofold rotational symmetry. As a result, its (11¯0) surface exhibits a pair of gapless Dirac surface states. Remarkably, these surface Dirac cones are “unpinned” in the sense that they are not restricted to locate at specific k points in the (11¯0) surface Brillouin zone. These unpinned 2D Dirac surface states could be probed directly via various spectroscopic techniques. Our analysis also reveals the presence of a distinct, previously uncharacterized set of 1D topological hinge states protected by the twofold rotational symmetry. Our study thus provides a comprehensive understanding of the topological band structure of bismuth.

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Galeeva, Alexandra V., Dmitry A. Belov, Aleksei S. Kazakov, Anton V. Ikonnikov, Alexey I. Artamkin, Ludmila I. Ryabova, Valentine V. Volobuev, Gunther Springholz, Sergey N. Danilov i Dmitry R. Khokhlov. "Photoelectromagnetic Effect Induced by Terahertz Laser Radiation in Topological Crystalline Insulators Pb1−xSnxTe". Nanomaterials 11, nr 12 (26.11.2021): 3207. http://dx.doi.org/10.3390/nano11123207.

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Topological crystalline insulators form a class of semiconductors for which surface electron states with the Dirac dispersion relation are formed on surfaces with a certain crystallographic orientation. Pb1−xSnxTe alloys belong to the topological crystalline phase when the SnTe content x exceeds 0.35, while they are in the trivial phase at x < 0.35. For the surface crystallographic orientation (111), the appearance of topologically nontrivial surface states is expected. We studied the photoelectromagnetic (PEM) effect induced by laser terahertz radiation in Pb1−xSnxTe films in the composition range x = (0.11–0.44), with the (111) surface crystallographic orientation. It was found that in the trivial phase, the amplitude of the PEM effect is determined by the power of the incident radiation, while in the topological phase, the amplitude is proportional to the flux of laser radiation quanta. A possible mechanism responsible for the effect observed presumes damping of the thermalization rate of photoexcited electrons in the topological phase and, consequently, prevailing of electron diffusion, compared with energy relaxation.

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Kargarian, Mehdi, Mohit Randeria i Yuan-Ming Lu. "Are the surface Fermi arcs in Dirac semimetals topologically protected?" Proceedings of the National Academy of Sciences 113, nr 31 (19.07.2016): 8648–52. http://dx.doi.org/10.1073/pnas.1524787113.

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Motivated by recent experiments probing anomalous surface states of Dirac semimetals (DSMs) Na3Bi and Cd3As2, we raise the question posed in the title. We find that, in marked contrast to Weyl semimetals, the gapless surface states of DSMs are not topologically protected in general, except on time-reversal-invariant planes of surface Brillouin zone. We first demonstrate this finding in a minimal four-band model with a pair of Dirac nodes at k=(0,0,±Q), where gapless states on the side surfaces are protected only near kz=0. We then validate our conclusions about the absence of a topological invariant protecting double Fermi arcs in DSMs, using a K-theory analysis for space groups of Na3Bi and Cd3As2. Generically, the arcs deform into a Fermi pocket, similar to the surface states of a topological insulator, and this pocket can merge into the projection of bulk Dirac Fermi surfaces as the chemical potential is varied. We make sharp predictions for the doping dependence of the surface states of a DSM that can be tested by angle-resolved photoemission spectroscopy and quantum oscillation experiments.

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Jost, Andreas, Michel Bendias, Jan Böttcher, Ewelina Hankiewicz, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp i in. "Electron–hole asymmetry of the topological surface states in strained HgTe". Proceedings of the National Academy of Sciences 114, nr 13 (9.03.2017): 3381–86. http://dx.doi.org/10.1073/pnas.1611663114.

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Topological insulators are a new class of materials with an insulating bulk and topologically protected metallic surface states. Although it is widely assumed that these surface states display a Dirac-type dispersion that is symmetric above and below the Dirac point, this exact equivalence across the Fermi level has yet to be established experimentally. Here, we present a detailed transport study of the 3D topological insulator-strained HgTe that strongly challenges this prevailing viewpoint. First, we establish the existence of exclusively surface-dominated transport via the observation of an ambipolar surface quantum Hall effect and quantum oscillations in the Seebeck and Nernst effect. Second, we show that, whereas the thermopower is diffusion driven for surface electrons, both diffusion and phonon drag contributions are essential for the hole surface carriers. This distinct behavior in the thermoelectric response is explained by a strong deviation from the linear dispersion relation for the surface states, with a much flatter dispersion for holes compared with electrons. These findings show that the metallic surface states in topological insulators can exhibit both strong electron–hole asymmetry and a strong deviation from a linear dispersion but remain topologically protected.

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Shen, Yuanyuan, Shengguo Guan i Chunyin Qiu. "Topological valley transport of spoof surface acoustic waves". Journal of Applied Physics 133, nr 11 (21.03.2023): 114305. http://dx.doi.org/10.1063/5.0137591.

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In recent years, topological physics has attracted broad attention in condensed matter systems. Here, we report an experimental study on topological valley transport of spoof surface acoustic waves (SAWs). Specifically, we realize valley pseudospins and a valley Hall phase transition by tuning the structural size of adjacent grooves. In addition to a direct visualization of the vortex chirality-locked beam splitting for the bulk valley states, valley-projected edge states are observed in straight and bent interface channels formed by two topologically distinct valley Hall insulating phases. The experimental data agree well with our numerical predictions. The topological transport of spoof SAWs, encoded with valley information, provides more possibilities in design novel acoustic devices based on the valley-contrasting physics.

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Rider, Marie S., Maria Sokolikova, Stephen M. Hanham, Miguel Navarro-Cía, Peter D. Haynes, Derek K. K. Lee, Maddalena Daniele i in. "Experimental signature of a topological quantum dot". Nanoscale 12, nr 44 (2020): 22817–25. http://dx.doi.org/10.1039/d0nr06523d.

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Shtanko, Oles, i Leonid Levitov. "Robustness and universality of surface states in Dirac materials". Proceedings of the National Academy of Sciences 115, nr 23 (22.05.2018): 5908–13. http://dx.doi.org/10.1073/pnas.1722663115.

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Ballistically propagating topologically protected states harbor exotic transport phenomena of wide interest. Here we describe a nontopological mechanism that produces such states at the surfaces of generic Dirac materials, giving rise to propagating surface modes with energies near the bulk band crossing. The robustness of surface states originates from the unique properties of Dirac–Bloch wavefunctions which exhibit strong coupling to generic boundaries. Surface states, described by Jackiw–Rebbi-type bound states, feature a number of interesting properties. Mode dispersion is gate tunable, exhibiting a wide variety of different regimes, including nondispersing flat bands and linear crossings within the bulk bandgap. The ballistic wavelike character of these states resembles the properties of topologically protected states; however, it requires neither topological restrictions nor additional crystal symmetries. The Dirac surface states are weakly sensitive to surface disorder and can dominate edge transport at the energies near the Dirac point.

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Li, Peng, James Kally, Steven S. L. Zhang, Timothy Pillsbury, Jinjun Ding, Gyorgy Csaba, Junjia Ding i in. "Magnetization switching using topological surface states". Science Advances 5, nr 8 (sierpień 2019): eaaw3415. http://dx.doi.org/10.1126/sciadv.aaw3415.

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Topological surface states (TSSs) in a topological insulator are expected to be able to produce a spin-orbit torque that can switch a neighboring ferromagnet. This effect may be absent if the ferromagnet is conductive because it can completely suppress the TSSs, but it should be present if the ferromagnet is insulating. This study reports TSS-induced switching in a bilayer consisting of a topological insulator Bi2Se3 and an insulating ferromagnet BaFe12O19. A charge current in Bi2Se3 can switch the magnetization in BaFe12O19 up and down. When the magnetization is switched by a field, a current in Bi2Se3 can reduce the switching field by ~4000 Oe. The switching efficiency at 3 K is 300 times higher than at room temperature; it is ~30 times higher than in Pt/BaFe12O19. These strong effects originate from the presence of more pronounced TSSs at low temperatures due to enhanced surface conductivity and reduced bulk conductivity.

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Rozprawy doktorskie na temat "Topological surface states"

Pantaleon, Peralta Pierre Anthony. "A theoretical investigation of 2D topological magnets". Thesis, University of Manchester, 2019. https://www.research.manchester.ac.uk/portal/en/theses/a-theoretical-investigation-of-2d-topological-magnets(1a330443-752a-4a41-b866-72f7a98c97a5).html.

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Since the discovery of the long-range ferromagnetic order in two-dimensional and multi-layered van der Waals crystals, and the observation of a nontrivial topology of the magnon bulk bands in the chromium trihalides, the bosonic honeycomb lattices have drawn significant attention within the condensed matter community. In this thesis, we employ a Heisenberg model with a Dzyaloshinsky-Moriya interaction in a honeycomb ferromagnetic lattice to study the properties of bulk and edge spin-wave excitations (magnon). By the Holstein-Primakoff transformations in the linear spin-wave approximation, the spin Hamiltonian is written as the bosonic equivalent of the Haldane model for spinless fermions. We present a simple bosonic tight binding formalism which allows us to obtain analytical solutions for the energy spectrum and wavefunctions. We investigate three basic boundaries in the honeycomb lattice: zigzag, bearded and armchair, and we derive analytical expressions for the energy band structure and wavefunctions for the bulk and edge states, and with both zero and nonzero Dzyaloshinsky-Moriya interaction. We find that in a lattice with a boundary, the intrinsic on-site interactions along the boundary sites generate an effective defect and this gives rise to Tamm-like edge states. If a nontrivial gap is induced, both Tamm-like and topologically protected edge states appear in the band structure. The effective defect can be strengthened by an external on-site potential, and the dispersion relation, velocity and magnon density of the edge states all become tunable. We also investigate the bond modulation in the bosonic Haldane model, where by introducing a Kekule bond modulation and with the analysis of the gap closing conditions and the bulk band inversions, we find a rich topological phase diagram for this system yet to be discovered. We identify four topological phases, verified by a numerical calculation of the Chern number, in terms of the Kekule modulation parameter and the Dzyaloshinsky-Moriya interaction. We present the bulk-edge correspondence for the magnons in a honeycomb lattice for both armchair and zigzag boundaries. We believed that our study in this thesis will be important for possible applications of magnons in data process devices such as magnonics.

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Kunst, Flore Kiki. "Topology Meets Frustration : Exact Solutions for Topological Surface States on Geometrically Frustrated Lattices". Licentiate thesis, Stockholms universitet, Fysikum, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-150281.

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Zhou, Wenwen. "STM probe on the surface electronic states of spin-orbit coupled materials". Thesis, Boston College, 2014. http://hdl.handle.net/2345/bc-ir:103564.

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Thesis advisor: Vidya Madhavan
Spin-orbit coupling (SOC) is the interaction of an electron's intrinsic angular momentum (spin) with its orbital momentum. The strength of this interaction is proportional to Z4 where Z is the atomic number, so generally it is stronger in atoms with higher atomic number, such as bismuth (Z=83) and iridium (Z=77). In materials composed of such heavy elements, the prominent SOC can be sufficient to modify the band structure of the system and lead to distinct phase of matter. In recent years, SOC has been demonstrated to play a critical role in determining the unusual properties of a variety of compounds. SOC associated materials with exotic electronic states have also provided a fertile platform for studying emergent phenomena as well as new physics. As a consequence, the research on these interesting materials with any insight into understanding the microscopic origin of their unique properties and complex phases is of great importance. In this context, we implement scanning tunneling microscopy (STM) and spectroscopy (STS) to explore the surface states (SS) of the two major categories of SOC involved materials, Bi-based topological insulators (TI) and Ir-based transition metal oxides (TMO). As a powerful tool in surface science which has achieved great success in wide variety of material fields, STM/STS is ideal to study the local density of states of the subject material with nanometer length scales and is able to offer detailed information about the surface electronic structure. In the first part of this thesis, we report on the electronic band structures of three-dimensional TIs Bi₂Te₃ and Bi₂Se₃. Topological insulators are distinct quantum states of matter that have been intensely studied nowadays. Although they behave like ordinary insulators in showing fully gapped bulk bands, they host a topologically protected surface state consisting of two-dimensional massless Dirac fermions which exhibits metallic behavior. Indeed, this unique gapless surface state is a manifestation of the non-trivial topology of the bulk bands, which is recognized to own its existence to the strong SOC. In chapter 3, we utilize quasiparticle interference (QPI) approach to track the Dirac surface states on Bi₂Te₃ up to ~800 meV above the Dirac point. We discover a novel interference pattern at high energies, which probably originates from the impurity-induced spin-orbit scattering in this system that has not been experimentally detected to date. In chapter 4, we discuss the topological SS evolution in (Bi_1-xIn_x)₂Se₃ series, by applying Landau quantization approach to extract the band dispersions on the surface for samples with different indium content. We propose that a topological phase transition may occur in this system when x reaches around 5%, with the experimental signature indicating a possible formation of gapped Dirac cone for the surface state at this doping. In the second part of this thesis, we focus on investigating the electronic structure of the bilayer strontium iridate Sr₃Ir₂O₇. The correlated iridate compounds belong to another domain of SOC materials, where the electronic interaction is involved as well. Specifically, the unexpected Mott insulating state in 5d-TMO Sr₂IrO₄ and Sr₃Ir₂O₇ has been suggested originate from the cooperative interplay between the electronic correlations with the comparable SOC, and the latter is even considered as the driving force for the extraordinary ground state in these materials. In chapter 6, we carried out a comprehensive examination of the electronic phase transition from insulating to metallic in Sr₃Ir₂O₇ induced by chemical doping. We observe the subatomic feature close to the insulator-to-metal transition in response with doping different carriers, and provide detailed studies about the local effect of dopants at particular sites on the electronic properties of the system. Additionally, the basic experimental techniques are briefly described in chapter 1, and some background information of the subject materials are reviewed in chapter 2 and chapter 5, respectively
Thesis (PhD) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics

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O'Neill, Christopher David. "Topological properties of SnTe and Fe3Sn2". Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20391.

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The aim of this thesis was to identify topologically protected states in the materials SnTe and Fe3Sn2. Such states are currently receiving a large amount of interest due to their applications for spintronic devices. Recently SnTe was discovered to be a crystalline topological insulator, a state of matter where its surface is highly conducting while the bulk remains insulating. However detection of these surface states is difficult using transport measurements, since the bulk is not totally insulating but still contains a large number of free carriers. SnTe undergoes a rhombohedral structural distortion on cooling caused by a soft transverse optic phonon, with the exact Tc strongly dependent on the carrier concentration. The distortion acts to lower crystal symmetry removing some of the symmetries that protect the surface state. Single crystal samples displaying the structural transition were grown and investigated using inelastic X-ray scattering to measure the phonon softening previously reported by other authors. The soft phonon was seen to recover again after distortion indicative of a 2nd order ferroelectric transition. This is the first reported discovery of the recovery showing the distortion is ferroelectric in nature. Shubnikov de Haas quantum oscillations were measured to study the Fermi surface under ambient and high hydrostatic pressure conditions. A distortion of the Fermi surface caused by the structural transition was evident, resulting in 4 distinct oscillation frequencies. However at applied pressures above 6 kbar, the transition was suppressed and only 1 oscillation measured. A two component Hall response also becomes apparent under high pressure. The possible origin of this and its relation to possible surface states is discussed. The anomalous Hall effect was also measured in the ferromagnet Fe3Sn2 which has a bilayer Kagome structure. Previous measurements on polycrystalline Fe3Sn2 suggested a non-collinear spin rotation from the spins pointing along the c-axis at high temperature to lying in the a-b plane below 80 K. A spin glass phase is then expected below 80 K. Single crystal magnetisation measurements carried out in this thesis show the spins are in the a-b plane at high temperatures and begin to display a ferromagnetic component along the c-axis approaching 80 K. The difference is accounted for by considering the demagnetising factor in the plate shaped single crystals. For this temperature range an applied field along the c-direction however rotates the moments towards c. At intermediate fields there are strong features evident in both the anomalous Hall effect and magnetoresistance. These features may be due to a topological Hall effect caused by a non-collinear spin structure. The possible existence of Skyrmion excitations was also recently discussed theoretically in Fe3Sn2. Our data is more suggestive of static Skyrmions known to cause topological Hall effects in MnSi.

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Lau, Alexander. "Symmetry-enriched topological states of matter in insulators and semimetals". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233930.

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Topological states of matter are a novel family of phases that elude the conventional Landau paradigm of phase transitions. Topological phases are characterized by global topological invariants which are typically reflected in the quantization of physical observables. Moreover, their characteristic bulk-boundary correspondence often gives rise to robust surface modes with exceptional features, such as dissipationless charge transport or non-Abelian statistics. In this way, the study of topological states of matter not only broadens our knowledge of matter but could potentially lead to a whole new range of technologies and applications. In this light, it is of great interest to find novel topological phases and to study their unique properties. In this work, novel manifestations of topological states of matter are studied as they arise when materials are subject to additional symmetries. It is demonstrated how symmetries can profoundly enrich the topology of a system. More specifically, it is shown how symmetries lead to additional nontrivial states in systems which are already topological, drive trivial systems into a topological phase, lead to the quantization of formerly non-quantized observables, and give rise to novel manifestations of topological surface states. In doing so, this work concentrates on weakly interacting systems that can theoretically be described in a single-particle picture. In particular, insulating and semi-metallic topological phases in one, two, and three dimensions are investigated theoretically using single-particle techniques.

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Berntsen, Magnus H. "Consequences of a non-trivial band-structure topology in solids : Investigations of topological surface and interface states". Doctoral thesis, KTH, Material- och nanofysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121974.

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The development and characterization of experimental setups for angle-resolved photoelectron spectroscopy (ARPES) and spin- and angle-resolved photoelectron spectroscopy (SARPES) is described. Subsequently, the two techniques are applied to studies of the electronic band structure in topologically non-trivial materials. The laser-based ARPES setup works at a photon energy of 10.5 eV and a typical repetition rate in the range 200 kHz to 800 kHz. By using a time-of-flight electron energy analyzer electrons emitted from the sample within a solid angle of up to ±15 degrees can be collected and analyzed simultaneously. The SARPES setup is equipped with a traditional hemispherical electron energy analyzer in combination with a mini-Mott electron polarimeter. The system enables software-controlled switching between angle-resolved spin-integrated and spin-resolved measurements, thus providing the possibility to orient the sample by mapping out the electronic band structure using ARPES before performing spin-resolved measurements at selected points in the Brillouin zone. Thin films of the topological insulators (TIs) Bi2Se3, Bi2Te3 and Sb2Te3 are grown using e-beam evaporation and their surface states are observed by means of ARPES. By using a combination of low photon energies and cryogenic sample temperatures the topological states originating from both the vacuum interface (surface) and the substrate interface are observed in Bi2Se3 films and Bi2Se3/Bi2Te3 heterostructures, with total thicknesses in the ultra-thin limit (six to eight quintuple layers), grown on Bi-terminated Si(111) substrates. Band alignment between Si and Bi2Se3 at the interface creates a band bending through the films. The band bending is found to be independent of the Fermi level (EF) position in the bulk of the substrate, suggesting that the surface pinning of EF in the Si(111) substrate remains unaltered after deposition of the TI films. Therefore, the type and level of doping of the substrate does not show any large influence on the size of the band bending. Further, we provide experimental evidence for the realization of a topological crystalline insulator (TCI) phase in the narrow-band semiconductor Pb1−xSnxSe. The TCI phase exists for temperatures below the transition temperature Tc and is characterized by an inverted bulk band gap accompanied by the existence of non-gapped surface states crossing the band gap. Above Tc the material is in a topologically trivial phase where the surface states are gapped. Thus, when lowering the sample temperature across Tc a topological phase transition from a trivial insulator to a TCI is observed. SARPES studies indicate a helical spin structure of the surface states both in the topologically trivial and the TCI phase.

QC 20130507

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Scholz, Markus Reiner [Verfasser], i Oliver [Akademischer Betreuer] Rader. "Spin polarization, circular dichroism, and robustness of topological surface states : a photoemission study / Markus Reiner Scholz ; Betreuer: Oliver Rader". Potsdam : Universität Potsdam, 2012. http://d-nb.info/1218400889/34.

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Mandal, Partha Sarathi [Verfasser], Oliver [Akademischer Betreuer] Rader, Hans-Joachim [Gutachter] Elmers i Martin [Gutachter] Weinelt. "Controlling the surface band gap in topological states of matter / Partha Sarathi Mandal ; Gutachter: Hans-Joachim Elmers, Martin Weinelt ; Betreuer: Oliver Rader". Potsdam : Universität Potsdam, 2020. http://d-nb.info/1221183621/34.

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Lambert, Fabian [Verfasser], Ilya [Gutachter] Eremin i Konstantin [Gutachter] Efetov. "Investigation of surface states in topological Weyl semi-metals and Weyl superconductors / Fabian Lambert ; Gutachter: Ilya Eremin, Konstantin Efetov ; Fakultät für Physik und Astronomie". Bochum : Ruhr-Universität Bochum, 2019. http://d-nb.info/1189421887/34.

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Tchoumakov, Sergueï. "Signatures relativistes en spectroscopie de matériaux topologiques : en volume et en surface". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS258/document.

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Dans cette thèse je me suis intéressé au caractère relativiste de matériaux topologiques tridimensionnels : les semi-métaux de Weyl et les isolants topologiques. Après une introduction aux états de surfaces et aux matériaux topologiques, je discute leurs propriétés de covariance sous les rotations trigonométriques et hyperboliques. Ces transformations me permettent de traiter les équations du mouvement d'un électron dans un champ magnétique ou à la surface, sous l'influence d'un champ électrique ou d'une inclinaison de la relation de dispersion. En première partie, je l'illustre dans le cas de la réponse magnéto-optique des semi-métaux de Weyl, en présence d'une inclinaison. Ces calculs sont en lien avec ma collaboration avec les expérimentateurs du LNCMI à Grenoble pour la caractérisation de la structure de bande de Cd₃As₂ où l'on montre que ce matériau est un semi-métal de Kane et non un semi-métal de Dirac dans la gamme de potentiels chimiques expérimentalement accessible. L'autre partie de cette thèse porte sur les états de surface des isolants topologiques où l'on montre qu'il existe des états de surface massifs au-delà de l'état de surface chiral. Ces états semblent avoir été observés par des études en ARPES d'échantillons de Bi₂Se₃ et Bi₂Te₃ oxydés et par des mesures de transport sur HgTe déformé. J'ai ainsi eu l'occasion de travailler avec les expérimentateurs du LPA à Paris sur le comportement des états de surface de HgTe sous forts effets de champ. Je termine par une discussion des états à l'interface entre un semi-métal de Weyl et un isolant dans le cas où le gap de ce dernier est suffisamment petit pour observer l'effet d'un champ magnétique et d'une inclinaison de la relation de dispersion sur les états de surface
During my PhD studies I focused on the relativistic properties of threedimensional topological materials, namely Weyl semimetals and topological insulators. After introducing surface states and topological materials I discuss their covariance in trigonometric and hyperbolic rotations. These transformations help to solve the equations of motion of an electron in a magnetic field or at the surface with an applied electric field or with a tilt in the band dispersion. In a first place, I illustrate these transformations for the magneto-optical response of tilted Weyl semimetals. This work is related to my collaboration with experimentalists at LNCMI, Grenoble for characterizing the band structure of Cd₃As₂ where we show that this material is a Kane semi-metal instead of a Dirac semi-metal in the experimentally accessible range of chemical doping. The other part of this thesis is concerned with the surface states of topological insulators. I show that massive surface states can also exist in addition to the chiral surface state due to band inversion. Such states may have already been observed in ARPES measurement of oxidized Bi₂Se₃ and Bi₂Te₃ and in transport measurement of strained bulk HgTe. I show the work we performed with experimentalists at LPA, Paris on the behavior of HgTe surface states for strong field effects. Finally, I discuss the states at the interface of a Weyl semimetal and a small gap insulator. In this situation, an applied magnetic field or the tilt of the band dispersion can strongly affect the observed surface states

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Książki na temat "Topological surface states"

Andrade, Erick Fernando. Visualizing Quasiparticle Scattering of Nematicity in NaFeAs and of Topological Surface States in MoTe2. [New York, N.Y.?]: [publisher not identified], 2018.

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Vladas, Sidoravicius, i Smirnov S. (Stanislav) 1970-, red. Probability and statistical physics in St. Petersburg: St. Petersburg School in Probability and Statistical Physics : June 18-29, 2012 : St. Petersburg State University, St. Petersburg, Russia. Providence, Rhode Island: American Mathematical Society, 2015.

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Murakami, S., i T. Yokoyama. Quantum spin Hall effect and topological insulators. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0017.

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This chapter begins with a description of quantum spin Hall systems, or topological insulators, which embody a new quantum state of matter theoretically proposed in 2005 and experimentally observed later on using various methods. Topological insulators can be realized in both two dimensions (2D) and in three dimensions (3D), and are nonmagnetic insulators in the bulk that possess gapless edge states (2D) or surface states (3D). These edge/surface states carry pure spin current and are sometimes called helical. The novel property for these edge/surface states is that they originate from bulk topological order, and are robust against nonmagnetic disorder. The following sections then explain how topological insulators are related to other spin-transport phenomena.

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Li, Y. Y., i J. F. Jia. Topological Superconductors and Majorana Fermions. Redaktor A. V. Narlikar. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780198738169.013.6.

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This article discusses recent developments relating to the so-called topological superconductors (TSCs), which have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions (MFs). It first provides a background on topological superconductivity as a novel quantum state of matter before turning to topological insulators (TIs) and superconducting heterostructures, with particular emphasis on the vortices of such materials and the Majorana mode within a vortex. It also considers proposals for realizing TSCs by proximity effects through TI/SC heterostructures as well as experimental efforts to fabricate artificial TSCs using nanowires, superconducting junctions, and ferromagnetic atomic chains on superconductors.

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Saitoh, E. Topological spin current. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0004.

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This chapter discusses another type of equilibrium-spin current similar to the exchange-spin current—the topological spin current. Topological spin currents are driven by topological-band structure and classified into bulk and surface topological spin currents. The former is confined onto electron-band manifolds, sometimes affecting their motions. This confinement is addressed through the standard method of combining the equations of motion and the Boltzmann equation for semi-classical electrons in a band. The latter class, on the other hand, is a surface-spin current, which is limited near surfaces of a three-dimensional system and flows along these surfaces. This type is known to appear in topological insulators, where the bulk is insulating but the surface or edge is electrically conducting due to the surface or edge state.

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Pauly, Christian. Strong and Weak Topology Probed by Surface Science: Topological Insulator Properties of Phase Change Alloys and Heavy Metal Graphene. Springer London, Limited, 2016.

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Pauly, Christian. Strong and Weak Topology Probed by Surface Science: Topological Insulator Properties of Phase Change Alloys and Heavy Metal Graphene. Spektrum Akademischer Verlag GmbH, 2016.

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Części książek na temat "Topological surface states"

Murakami, Shuichi. "Hybridization of Topological Surface States and Emergent States". W Topological Insulators, 11–30. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2015. http://dx.doi.org/10.1002/9783527681594.ch2.

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Suh, Hwansoo. "Probing Topological Insulator Surface States by Scanning Tunneling Microscope". W Topological Insulators, 217–44. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2015. http://dx.doi.org/10.1002/9783527681594.ch9.

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Díaz Fernández, Álvaro. "Surface States in $$\delta $$-doped Topological Boundaries". W Reshaping of Dirac Cones in Topological Insulators and Graphene, 141–59. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-61555-0_5.

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Johnson, P. D. "Dirac cones and topological states: topological insulators". W Physics of Solid Surfaces, 523–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/978-3-662-53908-8_127.

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Johnson, P. D. "Dirac cones and topological states: Dirac and Weyl semimetals". W Physics of Solid Surfaces, 535–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/978-3-662-53908-8_128.

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Carpentier, D. "Transport of Dirac surface states". W Topological Aspects of Condensed Matter Physics, 451–88. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780198785781.003.0010.

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Pal, Debarati, i Swapnil Patil. "Advancement of Topological Nanostructures for Various Applications". W Advanced Materials and Nano Systems: Theory and Experiment (Part-1), 190–212. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050745122010013.

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Topological materials are characterized by a unique band topology that is prominently distinct from ordinary metals and insulators. This new type of quantum material exhibits insulating bulk and conducting surface states that are robust against time-reversal invariant perturbations. In 2009, Bi2Se3 , Sb2Te3 and Bi2Te3 were predicted as 3D Topological insulators (TIs) with a single Dirac cone at the surface state. For application purposes, however, bulk conductivity due to Se vacancy in Bi2Se3 or anti site defects in Bi2Te3 has been a challenging issue. In order to achieve an enhanced surface conductivity over the bulk, nanomaterials are irreplaceable. Nanostructures' high surface to volume ratio provides a good platform for investigating the topological existence of surface states. By tuning the position of Fermi level through field effect gating, it is also possible to terminate the bulk residual carriers. Moreover, the synthesis of nanomaterials allows for morphological, electronic, and chemical regulation, resulting in the ability to design structures with desired TI properties at the nanoscale. In this article, we review various technological applications of nanostructured topological insulators. We also survey the implementation of topological nanomaterials in the field of optoelectronic devices, p-n junction, superconducting materials, field effect transistor, memory device and spintronics, ultrafast photodetection, and quantum computations.

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Hebard, Arthur. "Heterogeneous interfaces for teasing out the physics of embedded surface states". W Topological Phase Transitions and New Developments, 242. WORLD SCIENTIFIC, 2018. http://dx.doi.org/10.1142/9789813271340_0017.

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Zahid Hasan, M., Su-Yang Xu, David Hsieh, L. Andrew Wray i Yuqi Xia. "Topological Surface States: A New Type of 2D Electron Systems". W Contemporary Concepts of Condensed Matter Science, 143–74. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-444-63314-9.00006-8.

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Beindenkopf, Haim, Pedram Roushan i Ali Yazdani. "Visualizing Topological Surface States and their Novel Properties using Scanning Tunneling Microscopy and Spectroscopy". W Contemporary Concepts of Condensed Matter Science, 175–98. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-444-63314-9.00007-x.

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Streszczenia konferencji na temat "Topological surface states"

Yazdani, A. "Topological surface states: science and potential applications". W SPIE Defense, Security, and Sensing, redaktorzy Thomas George, M. Saif Islam i Achyut Dutta. SPIE, 2012. http://dx.doi.org/10.1117/12.920771.

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Devyatov, Eduard. "JOSEPHSON CURRENT TRANSFER BY WEYL TOPOLOGICAL SEMIMETALS SURFACE STATES". W International Forum “Microelectronics – 2020”. Joung Scientists Scholarship “Microelectronics – 2020”. XIII International conference «Silicon – 2020». XII young scientists scholarship for silicon nanostructures and devices physics, material science, process and analysis. LLC MAKS Press, 2020. http://dx.doi.org/10.29003/m1583.silicon-2020/145-149.

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Experiments on the study of topological surface states of magnetic and nonmagnetic Weyl semimetals charge transfer are presented. For surface states contribution the stationary and nonstationary Josephson effect realized at superconductortopological semi-metal-superconductor hybrid structures is applied.

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Bera, Sumit, P. Behera, A. K. Mishra, M. Krishnan, M. Gangrade, U. P. Deshpande, R. Venkatesh i V. Ganesan. "Possible evidence for topological surface states in nanocrystalline Bi2Te3". W DAE SOLID STATE PHYSICS SYMPOSIUM 2018. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5112983.

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Tasolamprou, Anna C., Maria Kafesaki, Costas M. Soukoulis, Eleftherios N. Economou i Thomas Koschny. "Topological surface states at C4 rotational symmetry photonic crystals bounded by air". W Conference on Lasers and Electro-Optics/Pacific Rim. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleopr.2022.cwp16g_03.

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We present an approach for manipulating topological states sustained at free space interfaces. Eigenvalue analysis corroborated by direct scattering simulations demonstrate the topological invariant jump, the mode's unidirectionalilty and immunity to defects and back-scattering.

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Xiang, Hong, i Dezhuan Han. "Topological Edge States in Systems of Spoof Surface Plasmon Polaritons". W 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC). IEEE, 2018. http://dx.doi.org/10.1109/csqrwc.2018.8455556.

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Li, Bolin, Hongyu Shi, Juan Chen, Anxue Zhang i Zhuo Xu. "Waveguide Coupler in Designer Surface Plasmon using Topological edge states". W 2021 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP). IEEE, 2021. http://dx.doi.org/10.1109/imws-amp53428.2021.9643865.

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Zhang, Shulei, i Giovanni Vignale. "Theory of bilinear magneto-electric resistance from topological-insulator surface states". W Spintronics XI, redaktorzy Henri Jaffrès, Henri-Jean Drouhin, Jean-Eric Wegrowe i Manijeh Razeghi. SPIE, 2018. http://dx.doi.org/10.1117/12.2323126.

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Weigand, Helena, Fabian Mooshammer, Fabian Sandner, Markus A. Huber, Martin Zizlsperger, Markus Plankl, Christian Weyrich i in. "Nanoscale Spectroscopy of Surface States on a Three-Dimensional Topological Insulator". W Frontiers in Optics. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/fio.2019.jw3a.121.

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Spektor, Grisha, Asaf David, Guy Bartal, Meir Orenstein i Alex Hayat. "Optical Access to Topological-Insulator Surface States with Plasmonic Rotating Fields". W CLEO: QELS_Fundamental Science. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/cleo_qels.2015.ftu2c.1.

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Dorin, Patrick, Xiang Liu i K. W. Wang. "Tunable Topological Wave Control in a Three-Dimensional Metastable Elastic Metamaterial". W ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69410.

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Abstract The concepts of topological insulators in condensed matter physics have been harnessed in elastic metamaterials to obtain quasi-lossless and omnidirectional guiding of elastic waves. Initial studies concerning topological wave propagation in elastic metamaterials focused on localizing waves in 1D or 2D mechanical structures. More recent investigations involving topological metamaterials have uncovered methodologies to achieve unprecedented control of elastic waves in 3D structures. However, a 3D topological metamaterial that can be tuned online to expand functionalities and respond to external conditions has yet to be developed. To advance the state of the art, this research proposes a tunable 3D elastic metamaterial that enables the reconfiguration of a topological waveguide through the switching of metastable states. Through careful design of internal bistable elements in the metastable unit cell, a switching methodology is developed to obtain topologically distinct lattices and a full topological bandgap. Analysis of the dispersion relation for a supercell reveals the presence of a topological surface state at the interface of topologically distinct lattices. Full-scale finite element simulations illustrate topological wave propagation in a 3D structure with a path that can be tailored on-demand. The research outcomes presented in this paper could be beneficial to potential applications requiring programmable and robust energy transport in 3D mechanical structures and serve as an inspiration for further work in adaptive 3D topological metamaterials.

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Raporty organizacyjne na temat "Topological surface states"

Qi, Xiao-Liang. Seeing the magnetic monopole through the mirror of topological surface states. Office of Scientific and Technical Information (OSTI), marzec 2010. http://dx.doi.org/10.2172/974188.

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Wu, Liang, Wang-Kong Tse, C. M. Morris, M. Brahlek, N. Koirala, S. Oh i N. P. Armitage. Observation of cyclotron resonance and electron-phonon coupling in surface states of the bulk-insulating topological insulator Cu_0.02Bi₂Se₃. Office of Scientific and Technical Information (OSTI), luty 2015. http://dx.doi.org/10.2172/1169665.

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Yong, Jie, Yeping Jiang, Demet Usanmaz, Stefano Curtarolo, Xiaohang Zhang, Linze Li, Xiaoqing Pan, Jongmoon Shin, Ichiro Tachuchi i Richard L. Greene. Composition-spread Growth and the Robust Topological Surface State of Kondo Insulator SmB6 Thin Films. Fort Belvoir, VA: Defense Technical Information Center, styczeń 2014. http://dx.doi.org/10.21236/ada610645.

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Yan, Yujie, i Jerome F. Hajjar. Automated Damage Assessment and Structural Modeling of Bridges with Visual Sensing Technology. Northeastern University, maj 2021. http://dx.doi.org/10.17760/d20410114.

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Recent advances in visual sensing technology have gained much attention in the field of bridge inspection and management. Coupled with advanced robotic systems, state-of-the-art visual sensors can be used to obtain accurate documentation of bridges without the need for any special equipment or traffic closure. The captured visual sensor data can be post-processed to gather meaningful information for the bridge structures and hence to support bridge inspection and management. However, state-of-the-practice data postprocessing approaches require substantial manual operations, which can be time-consuming and expensive. The main objective of this study is to develop methods and algorithms to automate the post-processing of the visual sensor data towards the extraction of three main categories of information: 1) object information such as object identity, shapes, and spatial relationships - a novel heuristic-based method is proposed to automate the detection and recognition of main structural elements of steel girder bridges in both terrestrial and unmanned aerial vehicle (UAV)-based laser scanning data. Domain knowledge on the geometric and topological constraints of the structural elements is modeled and utilized as heuristics to guide the search as well as to reject erroneous detection results. 2) structural damage information, such as damage locations and quantities - to support the assessment of damage associated with small deformations, an advanced crack assessment method is proposed to enable automated detection and quantification of concrete cracks in critical structural elements based on UAV-based visual sensor data. In terms of damage associated with large deformations, based on the surface normal-based method proposed in Guldur et al. (2014), a new algorithm is developed to enhance the robustness of damage assessment for structural elements with curved surfaces. 3) three-dimensional volumetric models - the object information extracted from the laser scanning data is exploited to create a complete geometric representation for each structural element. In addition, mesh generation algorithms are developed to automatically convert the geometric representations into conformal all-hexahedron finite element meshes, which can be finally assembled to create a finite element model of the entire bridge. To validate the effectiveness of the developed methods and algorithms, several field data collections have been conducted to collect both the visual sensor data and the physical measurements from experimental specimens and in-service bridges. The data were collected using both terrestrial laser scanners combined with images, and laser scanners and cameras mounted to unmanned aerial vehicles.

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