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61.
Topological nature of in‐gap bound states in disordered large‐gap monolayer transition metal dichalcogenides 下载免费PDF全文
We propose a physical model based on disordered (a hole punched inside a material) monolayer transition metal dichalcogenides (TMDs) to demonstrate a large‐gap quantum valley Hall insulator. We find an emergence of bound states lying inside the bulk gap of the TMDs. They are strongly affected by spin–valley coupling, rest‐ and kinetic‐mass terms and the hole size. In addition, in the whole range of the hole size, at least two in‐gap bound states with opposite angular momentum, circulating around the edge of the hole, exist.Their topological insulator (TI) feature is analyzed by the Chern number, characterized by spacial distribution of their probabilities and confirmed by energy dispersion curves (energy vs. angular momentum). It not only sheds light on overcoming low‐temperature operating limitation of existing narrow‐gap TIs, but also opens an opportunity to realize valley‐ and spin‐qubits. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
62.
Maxim A. Gorlach Mingzhao Song Alexey P. Slobozhanyuk Andrey A. Bogdanov Pavel A. Belov 《固体物理学:研究快报》2016,10(12):900-904
Employing nonlocal homogenization approach, we investigate the properties of a metamaterial consisting of parallel metallic wires with dielectric coating. We demonstrate that manipulation of dielectric contrast between wire dielectric shell and host material at fixed frequency results in dynamic switching of metamaterial dispersion regime from elliptic to the hyperbolic one, i.e. the topological transition takes place. It is proved that such transition can be induced by the variation of the metamaterial temperature. Our findings thus pave a way to the implementation of a tunable ‘elliptic‐hyperbolic’ metamaterial. 相似文献
63.
J.-B. Liu J.-H. Li X.-Y. Lü A. Zheng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):601-606
In this paper, we investigate the geometric phase of a composite system which is composed of two spin-
particles driven by a
time-varying magnetic field. Firstly, we consider the special case that only one subsystem driven by time-varying magnetic
field. Using the quantum jump
approach, we calculate the geometric phase associated with the adiabatic evolution of the system subjected to decoherence.
The results show that the lowest
order corrections to the phase in the no-jump trajectory is only quadratic in decoherence coefficient. Then, both subsystem
driven by time-varying magnetic
field is considered, we show that the geometric phase is related to the exchange-interaction coefficient and polar angle of
the magnetic field. 相似文献
64.
Yang Xin Dr. Boxuan Shen Prof. Mauri A. Kostiainen Prof. Guido Grundmeier Prof. Mario Castro Dr. Veikko Linko Dr. Adrian Keller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(33):8564-8571
The surface-assisted hierarchical assembly of DNA origami nanostructures is a promising route to fabricate regular nanoscale lattices. In this work, the scalability of this approach is explored and the formation of a homogeneous polycrystalline DNA origami lattice at the mica-electrolyte interface over a total surface area of 18.75 cm2 is demonstrated. The topological analysis of more than 50 individual AFM images recorded at random locations over the sample surface showed only minuscule and random variations in the quality and order of the assembled lattice. The analysis of more than 450 fluorescence microscopy images of a quantum dot-decorated DNA origami lattice further revealed a very homogeneous surface coverage over cm2 areas with only minor boundary effects at the substrate edges. At total DNA costs of € 0.12 per cm2, this large-scale nanopatterning technique holds great promise for the fabrication of functional surfaces. 相似文献
65.
A Combined Experimental and Theoretical Study on the Formation of Ag Filaments on β‐Ag2MoO4 Induced by Electron Irradiation 下载免费PDF全文
Juan Andrés Mateus M. Ferrer Lourdes Gracia Armando Beltran Valeria M. Longo Guilherme H. Cruvinel Ricardo L. Tranquilin Elson Longo 《Particle & Particle Systems Characterization》2015,32(6):646-651
A combined experimental and theoretical study is presented to understand the novel observed nucleation and early evolution of Ag filaments on β‐Ag2MoO4 crystals, driven by an accelerated electron beam from an electronic microscope under high vacuum. The growth process, chemical composition, and the element distribution in these filaments are analyzed in depth at the nanoscale level using field‐emission scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM) with energy‐dispersive spectroscopy (EDS) characterization. To complement experimental results, chemical stability, structural and electronic aspects have been studied systematically using first‐principles electronic structure theory within a quantum theory of atoms in molecules (QTAIM) framework. The Ag nucleation and formation on β‐Ag2MoO4 are a result of structural and electronic changes of the AgO4 tetrahedral cluster as a constituent building block of β‐Ag2MoO4, consistent with Ag metallic formation. The formation of Ag filament transforms the β‐Ag2MoO4 semiconductor from n‐ to p‐type concomitant with the appearance of Ag defects. 相似文献
66.
Dr. Guanjun Xiao Dr. Chunye Zhu Prof. Yanming Ma Prof. Bingbing Liu Prof. Guangtian Zou Prof. Bo Zou 《Angewandte Chemie (International ed. in English)》2014,53(3):729-733
There is an urgent need for the development in the field of the magnetism of topological insulators, owing to the necessity for the realization of the quantum anomalous Hall effect. Herein, we discuss experimentally fabricated nanostructured hierarchical architectures of the topological insulator Bi2Te3 without the introduction of any exotic magnetic dopants, in which intriguing room‐temperature ferromagnetism was identified. First‐principles calculations demonstrated that the intrinsic point defect with respect to the antisite Te site is responsible for the creation of a magnetic moment. Such a mechanism, which is different from that of a vacancy defect, provides new insights into the origins of magnetism. Our findings may pave the way for developing future Bi2Te3‐based dissipationless spintronics and fault‐tolerant quantum computation. 相似文献
67.
Rafał Jakieła Marta Galicka Piotr Dziawa Gunther Springholz Adam Barcz 《Surface and interface analysis : SIA》2020,52(3):71-75
Substitutional alloy Pb1 − xSnxSe is a new class of electronic materials called topological crystalline insulators, which at the temperature range from 0 K to 300 K exhibit topological state at compositions in the range 0.18 < x < 0.40 (in the rock-salt structure). In this report, we present a secondary ion mass spectrometry (SIMS) analysis technique to provide accurate Pb and Sn composition based on the measurement of PbCs+ and SnCs+ cluster ions intensities. Studies of Pb1 − xSnxSe bulk samples with various values of x show that x/(1 − x) is linear in relation to the intensity ratio of PbCs+/SnCs+ over the range from x = 0.15 to x = 0.41. This technique allows us to obtain an accurate Sn content for multilayered heterostructures, quantum wells containing Pb1 − xSnxSe with different x values for each layer. 相似文献
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