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排序方式: 共有175条查询结果,搜索用时 265 毫秒
61.
This paper reports that stoichiometric, amorphous, and uniform Er2O3 films are deposited on Si(001) substrates by a radio frequency magnetron sputtering technique. Ellipsometry measurements show that the refractive index of the Er2O3 films is very close to that of a single layer antireflection coating for a solar cell with an air surrounding medium during its working wavelength. For the 90-nm-thick film, the reflectance has a minimum lower than 3% at the wavelength of 600 nm and the weighted average reflectances (400-1000 nm) is 11.6%. The obtained characteristics indicate that Er2O3 films could be a promising candidate for antireflection coatings in solar cells. 相似文献
62.
近年来,探索新的拓扑量子结构、深入分析各种多聚化拓扑晶格中的新奇物理性质已经成为热点.并且,多聚化拓扑模型在量子光学等领域的研究也愈发深入,拥有广阔的发展前景.本文聚焦于研究三聚化非厄密晶格中的新奇拓扑特性.首先,若晶胞内最近邻正反向耦合不相等,三聚化模型中的体态和边缘态出现趋肤效应.其中,随着最近邻耦合正反系数差的增大,拓扑保护的边缘态的宽度和简并度均可被调制,边缘态数量也会减少.其次,当在考虑次近邻耦合的影响时,随着次近邻耦合系数在适当范围内变化,系统本征能谱的上下能隙及其中具有趋肤效应的边缘态也会发生不对称的变化.此外,当适当改变两种耦合系数,三聚化非厄密模型的体态和边缘态的局域程度也会随之发生变化. 相似文献
63.
Błażej Jaworowski Piotr Kaczmarkiewicz Paweł Potasz Arkadiusz Wójs 《Physics letters. A》2018,382(21):1419-1426
We investigate the stability of the one-dimensional limit of Laughlin-like fractional Chern insulator with respect to the interband interaction. We propose a construction for the excitations in the infinite-interaction case and show that the energy gap remains finite in the thermodynamic limit. Next, by means of exact diagonalization and Density Matrix Renormalization Group approaches, we consider deviations from ideal dimerization and show that they reduce the stability of the FCI-like states. Finally, to show that our approach is not restricted to one model, we identify the dimer structure behind the thin-torus limit of other system – the checkerboard lattice. 相似文献
64.
Topological insulators, a class of typical topological materials in both two dimensions and three dimensions,are insulating in bulk and metallic at surface. The spin-momentum locked surface states and peculiar transport properties exhibit promising potential applications on quantum devices, which generate extensive interest in the last decade. Dephasing is the process of the loss of phase coherence, which inevitably exists in a realistic sample. In this review, we focus on recent progress in dephasing effects on the topological insulators. In general, there are two types of dephasing processes: normal dephasing and spin dephasing. In two-dimensional topological insulators, the phenomenologically numerical investigation shows that the longitudinal resistance plateaus is robust against normal dephasing but fragile with spin dephasing. Several microscopic mechanisms of spin dephasing are then discussed. In three-dimensional topological insulators, the helical surface states exhibit a helical spin texture due to the spin-momentum locking mechanism. Thus, normal dephasing has close connection to spin dephasing in this case, and gives rise to anomalous “gap-like” feature. Dephasing effects on properties of helical surface states are investigated. 相似文献
65.
Quantum phase transition in topological insulators has drawn heightened attention in condensed matter physics and future device applications.Here we report the magnetotransport properties of single crystalline(Bi_(0.92)In_(0.08))_2Se_3.The average mobility of~1000 cm~2·V~(-1)·s~(-1)is obtained from the Lorentz law at the low field(3 T)up to 50 K.The quantum oscillations rise at a field of~5 T,revealing a high mobility of~1.4×10~4cm~2·V~(-1)·s~(-1)at 2 K.The Dirac surface state is evident by the nontrivial Berry phase in the Landau–Fan diagram.The properties make the(Bi_(0.92)In_(0.08))_2Se_3a promising platform for the investigation of quantum phase transition in topological insulators. 相似文献
66.
Jinzhong Zhang Abdur Rehman Jalil Pok-Lam Tse Jonas Kölzer Daniel Rosenbach Helen Valencia Martina Luysberg Martin Mikulics Gregory Panaitov Detlev Grützmacher Zhigao Hu Jia Grace Lu Thomas Schäpers 《Annalen der Physik》2020,532(8):2000273
Nanohybrid superconducting junctions using antimony telluride (Sb2Te3) topological insulator nanoribbons and Nb superconducting electrodes are fabricated using electron beam lithography and magnetron sputtering. The effects of bias current, temperature, and magnetic field on the transport properties of the junctions in a four-terminal measurement configuration are investigated. Two features are observed. First, the formation of a Josephson weak-link junction. The junction is formed by proximity-induced areas in the nanoribbon right underneath the inner Nb electrodes which are connected by the few tens of nanometers short Sb2Te3 bridge. At 0.5 K a critical current of 0.15 µA is observed. The decrease of the supercurrent with temperature is explained in the framework of a diffusive junction. Furthermore, the Josephson supercurrent is found to decrease monotonously with the magnetic field indicating that the structure is in the small-junction limit. As a second feature, a transition is also observed in the differential resistance at larger bias currents and larger magnetic fields, which is attributed to the suppression of the proximity-induced superconductive state in the nanoribbon area underneath the Nb electrodes. 相似文献
67.
Xi-guang Wang L. Chotorlishvili Guang-hua Guo J. Berakdar 《Physics letters. A》2018,382(16):1100-1107
Conversion of thermal energy into magnonic spin currents and/or effective electric polarization promises new device functionalities. A versatile approach is presented here for generating and controlling open circuit magnonic spin currents and an effective multiferroicity at a uniform temperature with the aid of spatially inhomogeneous, external, static electric fields. This field applied to a ferromagnetic insulator with a Dzyaloshinskii–Moriya type coupling changes locally the magnon dispersion and modifies the density of thermally excited magnons in a region of the scale of the field inhomogeneity. The resulting gradient in the magnon density can be viewed as a gradient in the effective magnon temperature. This effective thermal gradient together with local magnon dispersion result in an open-circuit, electric field controlled magnonic spin current. In fact, for a moderate variation in the external electric field the predicted magnonic spin current is on the scale of the spin (Seebeck) current generated by a comparable external temperature gradient. Analytical methods supported by full-fledge numerics confirm that both, a finite temperature and an inhomogeneous electric field are necessary for this emergent non-equilibrium phenomena. The proposal can be integrated in magnonic and multiferroic circuits, for instance to convert heat into electrically controlled pure spin current using for example nanopatterning, without the need to generate large thermal gradients on the nanoscale. 相似文献
68.
F. Ehlotzky 《Il Nuovo Cimento D》1992,14(5):517-525
Summary We shall investigate two models of harmonic generation in the spirit of the Keldysh theory and we shall apply these models
to hydrogen, for which more exact data for the rates of this process are available. Although our models correctly describe
the angular distribution, the intensity dependence (in the perturbation regime) and the selection rule for odd harmonics,
they badly fail in their predictions of the correct order of magnitude of the rates, in particular, of the formation of a
plateau. These latter findings disagree with the results of a similar model calculation by Beckeret al. for a δ-function potential.
The author of this paper has agreed to not receive the proofs for correction.
This research was supported in part by the Natural Sciences and Engineering Research Council of Canada. 相似文献
69.
A. Carbone F. Demichelis G. Kaniadakis F. Gozzo R. Murri N. Pinto L. Schiavulli G. Della Mea A. Drigo A. Paccagnella 《Il Nuovo Cimento D》1991,13(5):571-577
Summary The elemental composition and the optical properties of hydrogenated amorphous GaAs prepared by r.f. reactive sputtering at
different hydrogen and argon pressure and substrate temperature have been determined. From the dependence of the absorption
coefficient on photon energy the optical gap has been deduced according to the Tauc law. The data obtained for stoichiometric
samples are compared with similar data obtained by different authors. The influence of various deposition parameters on stoichiometry
and on the optical properties is briefly discussed. 相似文献
70.
Summary Several transport and optical properties have been studied onn-type CuIn5S8 single crystals. The energy gap at 0 K was determined from the electrical measurements to be 1.4 eV. An anisotropy of the
magnetoresistance effect was found and it was suggested that the minima of the conduction band were located at points along
the [100] directions ink-space. An optical-absorption band was found in an infrared region of (1÷1.6) μm and was attributed to the transitions from
the lowest conduction band situated along the [100] directions to an upper conduction band.
Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16,
1982. 相似文献