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Showing 1 to 20 of 26 for “"Bi2se3"”.
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The superconducting proximity effect in Bi2Se3 thin-films
… devices. In this work, the topological insulator Bi2Se3, which supports special metallic surface states as a consequence of the topology of its bulk bands, is tiled with micron-scale islands of the superconductor niobium. The superconducting islands interact with the Bi2Se3 and each other through …
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Spin-Orbit Delays in Photoemission from Bi2Te3 and Bi2Se3
Photoemission dynamics in solid-state materials can be observed in real-time via attosecond time-resolved photoelectron spectroscopy [1]. In this work *Reconstruction of Attosecond Beating By Interference of Two-photon Transitions* (RABBITT) [2] is applied to Bi<sub>*2*</sub>Te<sub>*3*</sub> and …
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Optical investigation of bismuth selenide (Bi2Se3) and antimony telluride (Sb2Te3).
… of two topological insulators, Bismuth Selenide (Bi2Se3) and Antimony Telluride (Sb2Te3), by optical spectroscopy reflection measurements in a wide frequency range (500 – 40000 cm−1 ) and temperature (13 to 300 K) . Utilizing Kramers-Kronig analysis, complex conductivity is calculated from which …
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Probing proximity-induced superconductivity in Nb- Bi2Se3 bilayers with low-temperature transport and Josephson interferometry
… exploring the superconducting properties of Nb-Bi2Se3 bilayers.
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Transport studies on proximity-coupled bismuth selenide
… topological insulators. To do this, we fabricate Bi2Se3 Josephson junctions and subject devices to in-plane and out-of-plane magnetic fields. This allows us to probe and manipulate the superconducting states of Bi2Se3 and therefore test predictions for what can happen at the intersection of …
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Angle-resolved photoemission and first-principles studies of topological semimetals and heterostructures
… (Sb) and the topological heterostructures Bi2Se3/Nb and Ag/Bi/Bi2Te3. First-principles calculations are used to determine the electronic band structure of the topological semimetal Sb for various spin-orbit coupling (SOC) strengths. Transitioning to a topological state typically involves a …
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Terahertz Spectroscopy of Topological Insulators and other 2-Dimensional Materials
… insulators (TIs) namely, bismuth selenide (Bi2Se3) and antimony telluride (Sb2Te3). Specifically, we investigate the optical behavior of Dirac materials using terahertz time domain spectroscopy (THz-TDS) contact-free optical technique, used to probe the low-energy excitations in strongly …
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Epitaxial growth and plasmonic coupling in topological insulator heterostructures
… ☐ The epitaxial growth of chalcogenide TI family Bi2Se3, Bi2Te3, and Sb2Te3 is dominated by van der Waals epitaxy. To produce high quality thin film for optical application, the growth of TI must be optimized to fit the needs on various substrates. The first part of this dissertation discusses the …
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Exotic superconductivity in quantum materials
… a topological superconductor candidate material, Bi2Se3 doped with Cu, Sn, or Nb atoms. Generally, superconductivity in such systems comes in two flavors: nematic, which breaks rotational symmetry of the crystal, and time-reversal breaking chiral.
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LOW-DIMENSIONAL CHALCOGENIDE BASED THERMOELECTRIC COMPOSITES
… Te1-xSex alloys as templates. On the other hand, Bi2Se3, Bi2Te3, Sb2Te3 nanoplates and their derivatives were also successfully fabricated. After nanostructures were obtained, we further combine them with polymers such as polyvinylidene fluoride to guarantee their flexibility in thermoelectric …
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VISUALIZATION OF CURRENT INDUCED SPIN ACCUMULATIONS IN THE STRONG SPIN-ORBITAL COUPLING MATERIALS
… spin accumulation at the channel edges of Bi2Se3 and BiSbTeSe2 topological insulators as well as Pt heavy metal by scanning photovoltage microscopy at room temperature. The spin polarization is along the out-of-plane direction with opposite signs for the two channel edges. The spin lifetime …
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Spin polarization, circular dichroism, and robustness of topological surface states
… Es wird gezeigt, dass in den Materialien Bi2Se3 und Bi2Te3, in übereinstimmung mit der Literatur, die entscheidenden Charakteristika eines topologischen Ober ächenzustands vorzu nden sind: Die Ober ächenzustände dieser Sys- teme durchqueren die Bandlücke in ungerader Anzahl, sie sind nicht …
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Room temperature spin-orbit torque switching induced by a topological insulator
… topological insulators. The comparison between Bi2Se3 and (Bi,Sb)2Te3 with less bulk conductivity suggests the surface states plays a significant role in generated the efficient spin-orbit torques. Furthermore, the effective spin Hall angle of topological insulators is determined to be several …
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Novel Precursors for the Synthesis of Metal Selenide Nanoparticles, Thin Films and Alloys
… precursor by hot injection method yields Bi2Se3 nanosheets. Thin films were also deposited at different temperatures on glass substrates and the water splitting efficiency of the oleylamine capped nanosheets was investigated. Both Sb2Se3 and Bi2Se3 shows p-type behavior as cathodic …
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Growth, Structural and Electrical Characterization of Topological Dirac Materials
… doping. Samples consisted of thin films of Bi2Se3, Sb2Te3, Cr doped Sb2Te3, bilayers of Dy doped Bi2Te3/Cr doped Sb2Te3 and Cd3As2 nanowires. It was found that a seed layer of an undoped topological insulator was a crucial first step to ensure high quality growth by molecular beam epitaxy, …
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Collective excitations in layered materials with momentum-resolved electron energy loss spectroscopy
… material, TiSe2, and a topological insulator, Bi2Se3. It was determined that the bosonic origin of quasiparticle kinks often seen in angle-resolved photoemission studies can be identified using M-EELS. Lastly, the observation of a novel electronic collective mode in TiSe2 is presented as strong …
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Determination of Realistic Effective Models for Weyl Semimetals of the TaAs Family
… topological insulators with the material family Bi2Se3 and Weyl semimetals with the material family TaAs as concrete application examples. After a detailed introduction into the peculiarities of topological quantum materials, the essential physical properties of topological insulators and Weyl …
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Exploiting the Spin Of Photons and Electrons in Light-Matter Interactions
… surface states in a 3D topological insu- lator Bi2Se3. The angular momentum conservation manifests itself in the spin- dependent optical selection rules and the generation of a photocurrent at zero bias voltage. Finally, we present the all-optical manipulation of magnetic order in ferrimag- …
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Atom-Based Geometrical Fingerprinting of Conformal Two-Dimensional Materials
… and, 3) multi layer 2D materials such as Bi2Se3 and WSe2. The lattice structures of these materials were created by designing a mechanical model - the mechanical model was devised in the form of a Gaussian bump and density-functional theory was used to inform the local height; and, the …
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Examining Topological Insulators and Topological Semimetals Using First Principles Calculations
… at side surfaces of a topological insulator, Bi2Se3, by using slab models within density functional theory. Two representative, experimentally achieved surfaces are examined, and it is shown that careful consideration of the crystal symmetry is necessary to understand the physics of the …
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