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1.
Because ideal PrBa2Cu3O7 superconducts at 90 K, it should be replaced by RBa2–u Sr
u
Cu2MO8 (where R is a light-mass rare earth and M is Nb or, preferably, Ta) as the insulator of choice for YBa2Cu3O7 Josephson junction or microstructure technology. Furthermore, (110)- or (100)-oriented substrates of RSr2Cu2MO8 may provide an opportunity for optimal device fabrication. 相似文献
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Yujing Liu Min Tang Mengmeng Meng Mingzhan Wang Jinxiong Wu Jianbo Yin Yubing Zhou Yunfan Guo Congwei Tan Wenhui Dang Shaoyun Huang H. Q. Xu Yong Wang Hailin Peng 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(18)
Nanostructures of ternary topological insulator (TI) Bi2Te2Se are, in principle, advantageous to the manifestation of topologically nontrivial surface states, due to significantly enhanced surface‐to‐volume ratio compared with its bulk crystals counterparts. Herein, the synthesis of 2D Bi2Te2Se crystals on mica via the van der Waals epitaxy method is explored and systematically the growth behaviors during the synthesis process are investigated. Accordingly, 2D Bi2Te2Se crystals with domain size up to 50 µm large and thickness down to 2 nm are obtained. A pronounced weak antilocalization effect is clearly observed in the 2D Bi2Te2Se crystals at 2 K. The method for epitaxial growth of 2D ternary Bi2Te2Se crystals may inspire materials engineering toward enhanced manifestation of the subtle surface states of TIs and thereby facilitate their potential applications in next‐generation spintronics. 相似文献
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Yumei Jing Shaoyun Huang Jinxiong Wu Mengmeng Meng Xiaobo Li Yu Zhou Hailin Peng Hongqi Xu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(42)
Quantum confined devices of 3D topological insulators are proposed to be promising and of great importance for studies of confined topological states and for applications in low‐energy‐dissipative spintronics and quantum information processing. The absence of energy gap on the topological insulator surface limits the experimental realization of a quantum confined system in 3D topological insulators. Here, the successful realization of single‐electron transistor devices in Bi2Te3 nanoplates using state‐of‐the‐art nanofabrication techniques is reported. Each device consists of a confined central island, two narrow constrictions that connect the central island to the source and drain, and surrounding gates. Low‐temperature transport measurements demonstrate that the two narrow constrictions function as tunneling junctions and the device shows well‐defined Coulomb current oscillations and Coulomb‐diamond‐shaped charge‐stability diagrams. This work provides a controllable and reproducible way to form quantum confined systems in 3D topological insulators, which should greatly stimulate research toward confined topological states, low‐energy‐dissipative devices, and quantum information processing. 相似文献
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Qisheng Wang Feng Wang Jie Li Zhenxing Wang Xueying Zhan Jun He 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(36):4613-4624
Topological crystalline insulators (TCIs) are recently discovered topological phase with robust surface states residing on high‐symmetry crystal surfaces. Different from conventional topological insulators (TIs), protection of surface states on TCIs comes from point‐group symmetry instead of time‐reversal symmetry in TIs. The distinct properties of TCIs make them promising candidates for the use in novel spintronics, low‐dissipation quantum computation, tunable pressure sensor, mid‐infrared detector, and thermoelectric conversion. However, similar to the situation in TIs, the surface states are always suppressed by bulk carriers, impeding the exploitation of topology‐induced quantum phenomenon. One effective way to solve this problem is to grow low‐dimensional TCIs which possess large surface‐to‐volume ratio, and thus profoundly increase the carrier contribution from topological surface states. Indeed, through persistent effort, researchers have obtained unique quantum transport phenomenon, originating from topological surface states, based on controllable growth of low‐dimensional TCIs. This article gives a comprehensive review on the recent progress of controllable synthesis and topological surface transport of low‐dimensional TCIs. The possible future direction about low‐dimensional TCIs is also briefly discussed at the end of this paper. 相似文献
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Investigation of PbBi thin films deposited by thermal evaporation was made in the range of 22–40% of bismuth. Low temperature resistivity and critical superconductive temperature depend strongly on bismuth concentration.SIMS depth profiling, X-ray diffraction and TEM analysis allow us to identify the mixture of crystallized HCPPb3Bi phase and other surface and internal phases. Drastic oxidation effects were observed on these layers; some additional thin film materials, such as indium and SiO were deposited upon PbBi to reduce oxidation.Low leakage current, niobium-oxide-Pb3Bi junctions were made with these alloys as counter-electrodes. 相似文献
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N. V. Tarakina S. Schreyeck M. Luysberg S. Grauer C. Schumacher G. Karczewski K. Brunner C. Gould H. Buhmann R. E. Dunin‐Borkowski L. W. Molenkamp 《Advanced Materials Interfaces》2014,1(5)
The microstructure of Bi2Se3 topological‐insulator thin films grown by molecular beam epitaxy on InP(111)A and InP(111)B substrates that have different surface roughnesses has been studied in detail using X‐ray diffraction, X‐ray reflectivity, atomic force microscopy and probe‐corrected scanning transmission electron microscopy. The use of a rough Fe‐doped InP(111)B substrate results in complete suppression of twin formation in the Bi2Se3 thin films and a perfect interface between the films and their substrates. The only type of structural defect that persists in the twin‐free films is an antiphase domain boundary, which is associated with variations in substrate height. We also show that the substrate surface termination influences which family of twin domains dominates. 相似文献
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High‐Mobility Sm‐Doped Bi2Se3 Ferromagnetic Topological Insulators and Robust Exchange Coupling 下载免费PDF全文
Taishi Chen Wenqing Liu Fubao Zheng Ming Gao Xingchen Pan Gerrit van der Laan Xuefeng Wang Qinfang Zhang Fengqi Song Baigeng Wang Baolin Wang Yongbing Xu Guanghou Wang Rong Zhang 《Advanced materials (Deerfield Beach, Fla.)》2015,27(33):4823-4829
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Fucong Fei Shuai Zhang Minhao Zhang Syed Adil Shah Fengqi Song Xuefeng Wang Baigeng Wang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(27):1904593
A topological insulator (TI) is a kind of novel material hosting a topological band structure and plenty of exotic topological quantum effects. Achieving quantized electrical transport, including the quantum Hall effect (QHE) and the quantum anomalous Hall effect (QAHE), is an important aspect of realizing quantum devices based on TI materials. Intense efforts are made in this field, in which the most essential research is based on the optimization of realistic TI materials. Herein, the TI material development process is reviewed, focusing on the realization of quantized transport. Especially, for QHE, the strategies to increase the surface transport ratio and decrease the threshold magnetic field of QHE are examined. For QAHE, the evolution history of magnetic TIs is introduced, and the recently discovered magnetic TI candidates with intrinsic magnetizations are discussed in detail. Moreover, future research perspectives on these novel topological quantum effects are also evaluated. 相似文献
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Minggang Xie Chunguang Li Siqi Zhang Zhe Zhang Yuxin Li Xiao-Bo Chen Zhan Shi Shouhua Feng 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(33):2301436
The development of fast charging materials offers a viable solution for large-scale and sustainable energy storage needs. However, it remains a critical challenge to improve the electrical and ionic conductivity for better performance. Topological insulator (TI), a topological quantum material that has attracted worldwide attention, hosts unusual metallic surface states and consequent high carrier mobility. Nevertheless, its potential in promising high-rate charging capability has not been fully realized and explored. Herein, a novel Bi2Se3-ZnSe heterostructure as excellent fast charging material for Na+ storage is reported. Ultrathin Bi2Se3 nanoplates with rich TI metallic surfaces are introduced as an electronic platform inside the material, which greatly reduces the charge transfer resistance and improves the overall electrical conductivity. Meanwhile, the abundant crystalline interfaces between these two selenides promote Na+ migration and provide additional active sites as well. As expected, the composite delivers the excellent high-rate performance of 360.5 mAh g−1 at 20 A g−1 and maintains its electrochemical stability of 318.4 mAh g−1 after 3000 long cycles, which is the record high for all reported selenide-based anodes. This work is anticipated to provide alternative strategies for further exploration of topological insulators and advanced heterostructures. 相似文献
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On‐Chip Andreev Devices: Hard Superconducting Gap and Quantum Transport in Ballistic Nb–In0.75Ga0.25As‐Quantum‐Well–Nb Josephson Junctions 下载免费PDF全文
《Advanced materials (Deerfield Beach, Fla.)》2017,29(37)
A superconducting hard gap in hybrid superconductor–semiconductor devices has been found to be necessary to access topological superconductivity that hosts Majorana modes (non‐Abelian excitation). This requires the formation of homogeneous and barrier‐free interfaces between the superconductor and semiconductor. Here, a new platform is reported for topological superconductivity based on hybrid Nb–In0.75Ga0.25As‐quantum‐well–Nb that results in hard superconducting gap detection in symmetric, planar, and ballistic Josephson junctions. It is shown that with careful etching, sputtered Nb films can make high‐quality and transparent contacts to the In0.75Ga0.25As quantum well, and the differential resistance and critical current measurements of these devices are discussed as a function of temperature and magnetic field. It is demonstrated that proximity‐induced superconductivity in the In0.75Ga0.25As‐quantum‐well 2D electron gas results in the detection of a hard gap in four out of seven junctions on a chip with critical current values of up to 0.2 µA and transmission probabilities of >0.96. The results, together with the large g ‐factor and Rashba spin–orbit coupling in In0.75Ga0.25As quantum wells, which indeed can be tuned by the indium composition, suggest that the Nb–In0.75Ga0.25As–Nb system can be an excellent candidate to achieve topological phase and to realize hybrid topological superconducting devices. 相似文献
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Persistent photoconductivity is an interesting and unusual property of high temperature superconductors. Illumination of these compounds can lead to a change in doping that is persistent at low temperature and relaxes back to its initial value at elevated temperatures. This photodoping can give rise to an improvement of superconducting properties, which is contrary to the illumination effects in conventional superconductors. Furthermore, these photo-induced effects can also be used to probe and modify the properties of grain boundaries in grain boundary Josephson junctions. This paper reviews the experimental data and proposed theoretical models related to these photoinduced effects. 相似文献
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J. T. Peltonen A. V. Timofeev M. Meschke J. P. Pekola 《Journal of Low Temperature Physics》2007,146(1-2):135-159
We discuss the use of a hysteretic Josephson junction to detect current fluctuations with frequencies below the plasma frequency
of the junction. These adiabatic fluctuations are probed by switching measurements observing the noise-affected average rate
of macroscopic quantum tunneling of the detector junction out of its zero-voltage state. In a proposed experimental scheme,
frequencies of the noise are limited by an on-chip filtering circuit. The third cumulant of current fluctuations at the detector
is related to an asymmetry of the switching rates.
相似文献
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Sepideh Izadi Ahana Bhattacharya Sarah Salloum Jeong Woo Han Lauritz Schnatmann Ulrike Wolff Nicolas Perez Georg Bendt Inga Ennen Andreas Hütten Kornelius Nielsch Stephan Schulz Martin Mittendorff Gabi Schierning 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(11):2204850
Three-dimensional topological insulators (3D TI) exhibit conventional parabolic bulk bands and protected Dirac surface states. A thorough investigation of the different transport channels provided by the bulk and surface carriers using macroscopic samples may provide a path toward accessing superior surface transport properties. Bi2Te3 materials make promising 3D TI models; however, due to their complicated defect chemistry, these materials have a high number of charge carriers in the bulk that dominate the transport, even as nanograined structures. To partially control the bulk charge carrier density, herein the synthesis of Te-enriched Bi2Te3 nanoparticles is reported. The resulting nanoparticles are compacted into nanograined pellets of varying porosity to tailor the surface-to-volume ratio, thereby emphasizing the surface transport channels. The nanograined pellets are characterized by a combination of resistivity, Hall- and magneto-conductance measurements together with (THz) time-domain reflectivity measurements. Using the Hikami-Larkin-Nagaoka (HLN) model, a characteristic coherence length of ≈200 nm is reported that is considerably larger than the diameter of the nanograins. The different contributions from the bulk and surface carriers are disentangled by THz spectroscopy, thus emphasizing the dominant role of the surface carriers. The results strongly suggest that the surface transport carriers have overcome the hindrance imposed by nanoparticle boundaries. 相似文献
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Jiazhen Wu Fucai Liu Can Liu Yong Wang Changcun Li Yangfan Lu Satoru Matsuishi Hideo Hosono 《Advanced materials (Deerfield Beach, Fla.)》2020,32(23):2001815
2D magnets and their engineered magnetic heterostructures are intriguing materials for both fundamental physics and application prospects. On the basis of the recently discovered intrinsic magnetic topological insulators (MnBi2Te4)(Bi2Te3)n, here, a new type of magnet, in which the magnetic layers are separated by a large number of non-magnetic layers and become magnetically independent, is proposed. This magnet is named as a single-layer magnet, regarding the vanishing interlayer exchange coupling. Theoretical calculations and magnetization measurements indicate that, the decoupling of the magnetic layers starts to emerge from n = 2 and 3, as revealed by a unique slow-relaxation behavior below a ferromagnetic-type transition at Tc = 12–14 K. Magnetization data analysis shows that the proposed new magnetic states have a strong uniaxial anisotropy along the c-axis, forming an Ising-type magnetic structure, where Tc is the ordering temperature for each magnetic layer. The characteristic slow relaxation, which exists only along the c-axis but is absent along the ab plane, can be ascribed to interlayer coherent spin rotation and/or intralayer domain wall movement. The present results will stimulate further theoretical and experimental investigations for the prototypical magnetic structures, and their combination with the topological surface states may lead to exotic physical properties. 相似文献
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Caterina Lamuta Anna Cupolillo Antonio Politano Ziya S. Aliev Mahammad B. Babanly Evgueni V. Chulkov 《Nano Research》2016,9(4):1032-1042
Bismuth telluride (Bi2Te3) is one of the most important commercial thermoelectric materials. In recent years, the discovery of topologically protected surface states in Bi chalcogenides has paved the way for their application in nanoelectronics. Determination of the fracture toughness plays a crucial role for the potential application of topological insulators in flexible electronics and nanoelectromechanical devices. Using depth-sensing nanoindentation tests, we investigated for the first time the fracture toughness of bulk single crystals of Bi2Te3 topological insulators, grown using the Bridgman-Stockbarger method. Our results highlight one of the possible pitfalls of the technology based on topological insulators. 相似文献
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通过水热法合成不同Se掺杂量的Bi2Te3-xSex (0 ≤x ≤0.45)纳米粉体, 采用放电等离子烧结技术, 制备出致密度较高的块体材料。通过X射线衍射、扫描电镜、透射电镜等测试手段对材料的微结构进行了表征, 并重点研究了含有不同Se掺杂量块体材料的显微结构和热电性能。结果表明: Se元素的掺杂使得粉体XRD特征衍射峰向高角度偏移, 并且衍射峰出现宽化, 晶粒尺寸变小。随着Se掺杂量的增加, 块体材料的电导率先增大后减小; Se元素的掺杂有效地降低了材料的热导率, 并提高了材料的Seebeck系数。研究结果表明: 在整个测试温度区间, 所有经过Se掺杂的样品ZT值都高于未掺杂样品。当Se掺杂量为0.3时, 样品具有最大的ZT值, 平均约为0.51, 并在475 K时达到最大值0.57, 相比未经Se掺杂的Bi2Te3提高了159%。 相似文献