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CN 11-5639/O4
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All Express Letters

Improvement of laser damage thresholds of fused silica by ultrasonic-assisted hydrofluoric acid etching Hot!

Yuan Li(李源), Hongwei Yan(严鸿维), Ke Yang(杨科), Caizhen Yao(姚彩珍), Zhiqiang Wang(王志强), Chunyan Yan(闫春燕), Xinshu Zou(邹鑫书), Xiaodong Yuan(袁晓东), Liming Yang(杨李茗), Xin Ju(巨新)
Chin. Phys. B, 2017, 26 (11): 118104 doi: 10.1088/1674-1056/26/11/118104
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Polished fused silica samples were etched for different durations by using hydrofluoric (HF) acid solution with HF concentrations in an ultrasonic field. Surface and subsurface polishing residues and molecular structure parameters before and after the etching process were characterized by using a fluorescence microscope and infrared (IR) spectrometer, respectively. The laser induced damage thresholds (LIDTs) of the samples were measured by using pulsed nanosecond laser with wavelength of 355 nm. The results showed that surface and subsurface polishing residues can be effectively reduced by the acid etching process, and the LIDTs of fused silica are significantly improved. The etching effects increased with the increase of the HF concentration from 5 wt.% to 40 wt.%. The amount of polishing residues decreased with the increase of the etching duration and then kept stable. Simultaneously, with the increase of the etching time, the mechanical strength and molecular structure were improved.

An easy way to controllably synthesize one-dimensional SmB6 topological insulator nanostructures and exploration of their field emission applications Hot!

Xun Yang(杨汛), Hai-Bo Gan(甘海波), Yan Tian(田颜), Ning-Sheng Xu(许宁生), Shao-Zhi Deng(邓少芝), Jun Chen(陈军), Huanjun Chen(陈焕君), Shi-Dong Liang(梁世东), Fei Liu(刘飞)
Chin. Phys. B, 2017, 26 (11): 118103 doi: 10.1088/1674-1056/26/11/118103
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A convenient fabrication technique for samarium hexaboride (SmB6) nanostructures (nanowires and nanopencils) is developed, combining magnetron-sputtering and chemical vapor deposition. Both nanostructures are proven to be single crystals with cubic structure, and they both grow along the[001] direction. Formation of both nanostructures is attributed to the vapor-liquid-solid (VLS) mechanism, and the content of boron vapor is proposed to be the reason for their different morphologies at various evaporation distances. Field emission (FE) measurements show that the maximum current density of both the as-grown nanowires and nanopencils can be several hundred μA/cm2, and their FN plots deviate only slightly from a straight line. Moreover, we prefer the generalized Schottky-Nordheim (SN) model to comprehend the difference in FE properties between the nanowires and nanopencils. The results reveal that the nonlinearity of FN plots is attributable to the effect of image potential on the FE process, which is almost independent of the morphology of the nanostructures. All the research results suggest that the SmB6 nanostructures would have a more promising future in the FE area if their surface oxide layer was eliminated in advance.

Fluctuating specific heat in two-band superconductors Hot!

Lei Qiao(乔雷), Cheng Chi(迟诚), Jiangfan Wang(王江帆)
Chin. Phys. B, 2017, 26 (11): 117401 doi: 10.1088/1674-1056/26/11/117401
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Theory of thermal fluctuations in two-band superconductors under an essentially homogeneous magnetic field is developed within the framework of the two-band Ginzburg-Landau theory. The fluctuating specific heat is calculated by using the optimized self-consistent perturbation approach and the results are applied to analyze the thermodynamic data of the iron-based superconductors Ba1-xKxFe2As2 with x~0.4, which have been suggested to have a two-band structure by recent experiments. We estimate the fluctuation strength in this material and find that the specific heat is described well with the Ginzburg number Gi=4·10-4. The influence of interband coupling strength is investigated and the result of the two-band Gaussian approximation approach is compared.

Interfacial nanobubbles produced by long-time preserved cold water Hot!

Li-Min Zhou(周利民), Shuo Wang(王硕), Jie Qiu(邱杰), Lei Wang(王磊), Xing-Ya Wang(王兴亚), Bin Li(李宾), Li-Juan Zhang(张立娟), Jun Hu(胡钧)
Chin. Phys. B, 2017, 26 (10): 106803 doi: 10.1088/1674-1056/26/10/106803
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Interfacial gaseous nanobubbles which have remarkable properties such as unexpectedly long lifetime and significant potential applications, are drawing more and more attention. However, the recent dispute about the contamination or gas inside the nanobubbles causes a large confusion due to the lack of simple and clean method to produce gas nanobubbles. Here we report a convenient and clean method to effectively produce interfacial nanobubbles based on a pure water system. By adding the cold water cooled at 4 ℃ for more than 48 h onto highly oriented pyrolytic graphite (HOPG) surface, we find that the average density and total volume of nanobubbles are increased to a high level and mainly dominated by the concentrations of the dissolved gases in cold water. Our findings and methods are crucial and helpful for settling the newly arisen debates on gas nanobubbles.

Extracting hidden weak sinusoidal signal with short duration from noisy data:Analytical theory and computational realization Hot!

Ying Zhang(张英), Zhaoyang Zhang(张朝阳), Hong Qian(钱弘), Gang Hu(胡岗)
Chin. Phys. B, 2017, 26 (10): 100508 doi: 10.1088/1674-1056/26/10/100508
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Signal detection is both a fundamental topic of data science and a great challenge for practical engineering. One of the canonical tasks widely investigated is detecting a sinusoidal signal of known frequency ω with time duration T:I(t)=Acos ω t+Γ(t), embedded within a stationary noisy data. The most direct, and also believed to be the most efficient, method is to compute the Fourier spectral power at ω:B=|2/T0T I(t)eiωtdt|. Whether one can out-perform the linear Fourier approach by any other nonlinear processing has attracted great interests but so far without a consensus. Neither a rigorous analytic theory has been offered. We revisit the problem of weak signal, strong noise, and finite data length T=O(1), and propose a signal detection method based on resonant filtering. While we show that the linear approach of resonant filters yield a same signal detection efficiency in the limit of T→∞, for finite time length T=O(1), our method can improve the signal detection due to the highly nonlinear interactions between various characteristics of a resonant filter in finite time with respect to transient evolution. At the optimal match between the input I(t), the control parameters, and the initial preparation of the filter state, its performance exceeds the above threshold B considerably. Our results are based on a rigorous analysis of Gaussian processes and the conclusions are supported by numerical computations.

Measurement of transient Raman spectrum on gas-gun loading platform and its application in liquid silane Hot!

Yi-Gao Wang(汪贻高), Fu-Sheng Liu(刘福生), Qi-Jun Liu(刘其军), Wen-Peng Wang(王文鹏), Ming-Jian Zhang(张明建), Feng Xi(习锋), Ling-Cang Cai(蔡灵仓), Ning-Chao Zhang(张宁超)
Chin. Phys. B, 2017, 26 (10): 103301 doi: 10.1088/1674-1056/26/10/103301
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Combining a low temperature liquidizing system with a transient Raman spectroscopy, a new experimental technique is established for the first time on a two-stage light-gas gun, and it is employed to study shock-compressed fluid silane. With this experimental technique, we first obtain a Raman peak shift relating to the Si-H stretching vibration mode of molecular liquid silane under shock loading conditions. The Raman peak of 2184 cm-1 at an initial state of 0 GPa and 85 K moves to 2223.4 cm-1 at a shocked state of 10.5 GPa and 950 K, and its full width of half maximum broadens from 33 cm-1 to 118 cm-1. The shocked temperature, calculated by the thermodynamic equation of state, is well consistent with that estimated by the Doppler broadening function.

Ultrafast interlayer photocarrier transfer in graphene-MoSe2 van der Waals heterostructure Hot!

Xin-Wu Zhang(张心悟), Da-Wei He(何大伟), Jia-Qi He(何佳琪), Si-Qi Zhao(赵思淇), Sheng-Cai Hao(郝生财), Yong-Sheng Wang(王永生), Li-Xin Yi(衣立新)
Chin. Phys. B, 2017, 26 (9): 097202 doi: 10.1088/1674-1056/26/9/097202
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We report the fabrication and photocarrier dynamics in graphene-MoSe2 heterostructures. The samples were fabricated by mechanical exfoliation and manual stacking techniques. Ultrafast laser measurements were performed on the heterostructure and MoSe2 monolayer samples. By comparing the results, we conclude that photocarriers injected in MoSe2 of the heterostructure transfer to graphene on an ultrafast time scale. The carriers in graphene alter the optical absorption coefficient of MoSe2. These results illustrate the potential applications of this material in optoelectronic devices.

Synthesis and magnetotransport properties of Bi2Se3 nanowires Hot!

Kang Zhang(张亢), Haiyang Pan(潘海洋), Zhongxia Wei(魏仲夏), Minhao Zhang(张敏昊), Fengqi Song(宋风麒), Xuefeng Wang(王学锋), Rong Zhang(张荣)
Chin. Phys. B, 2017, 26 (9): 096101 doi: 10.1088/1674-1056/26/9/096101
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Bi2Se3, as a three-dimensional topological insulator, has attracted worldwide attention for its unique surface states which are protected by time-reversal symmetry. Here we report the synthesis and characterization of high-quality single-crystalline Bi2Se3 nanowires. Bi2Se3 nanowires were synthesized by chemical vapor deposition (CVD) method via gold-catalyzed vapor-liquid-solid (VLS) mechanism. The structure and morphology were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. In magnetotransport measurements, the Aharonov-Bohm (AB) effect was observed in a nanowire-based nanodevice, suggesting the existence of surface states in Bi2Se3 nanowires.

Fabrication and characterization of ultra-low noise narrow and wide band Josephson parametric amplifiers Hot!

Keqiang Huang(黄克强), Qiujiang Guo(郭秋江), Chao Song(宋超), Yarui Zheng(郑亚锐), Hui Deng(邓辉), Yulin Wu(吴玉林), Yirong Jin(金贻荣), Xiaobo Zhu(朱晓波), Dongning Zheng(郑东宁)
Chin. Phys. B, 2017, 26 (9): 094203 doi: 10.1088/1674-1056/26/9/094203
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We have fabricated two types of lumped-element Josephson parameter amplifiers (JPAs) by using a multilayer micro-fabrication process involving wet etching of Al films. The first type is a narrow band JPA which shows typical gain above 14 dB in a bandwidth around 35 MHz. The second type is a wideband JPA which is coupled to an input 50 Ω transmission line via an impedance transformer that changes the impedance from about 15 Ω on the non-linear resonator side to 50 Ω on the input transmission line side. The wideband JPA could operate in a 200 MHz range with a gain higher than 14 dB. The amplifiers were used for superconducting qubit readout. The results showed that the signal to noise ratio and hence the readout fidelity were improved significantly.

Gas treatment protection of metallic lithium anode Hot!

Wen-jun Li(李文俊), Quan Li(李泉), Jie Huang(黄杰), Jia-yue Peng(彭佳悦), Geng Chu(褚赓), Ya-xiang Lu(陆雅翔), Jie-yun Zheng(郑杰允), Hong Li(李泓)
Chin. Phys. B, 2017, 26 (8): 088202 doi: 10.1088/1674-1056/26/8/088202
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The effects of different coating layers on lithium metal anode formed by reacting with different controlled atmospheres (argon, CO2-O2 (2:1), N2, and CO2-O2-N2 (2:1:3)) have been investigated. The obtained XRD, second ion mass spectroscopy (SIMS), and scanning probe microscope (SPM) results demonstrate the formation of coating layers composed of Li2CO3, Li3N, and the mixture of them on lithium tablets, respectively. The Li/Li symmetrical cell and Li/S cell are assembled to prove the advantages of the protected lithium tablet on electrochemical performance. The comparison of SEM and SIMS characterizations before/after cycles clarifies that an SEI-like composition formed on the lithium tablets could modulate the interfacial stabilization between the lithium foil and the ether electrolyte.

Thermo-controllable self-assembled structures of single-layer 4, 4"-diamino-p-terphenyl molecules on Au (110) Hot!

Junhai Ren(任俊海), Deliang Bao(包德亮), Li Dong(董立), Lei Gao(高蕾), Rongting Wu(武荣庭), Linghao Yan(闫凌昊), Aiwei Wang(王爱伟), Jiahao Yan(严佳浩), Yeliang Wang(王业亮), Shixuan Du(杜世萱), Qing Huan(郇庆), Hongjun Gao(高鸿钧)
Chin. Phys. B, 2017, 26 (8): 086801 doi: 10.1088/1674-1056/26/8/086801
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Here we report the thermo-controllable self-assembled structures of single-layer 4, 4"-diamino-p-terphenyl (DAT) molecules on Au (110), which are investigated by scanning tunneling microscopy (STM) combined with density functional theory (DFT) based calculations. With the deposition of monolayer DAT molecules on Au (110) and subsequent annealing at 100 ℃, all DAT molecules adsorb on a (1×5) reconstructed surface with a ladder-like structure. After annealing the sample at about 200 ℃, STM images show three distinct domains, including DAT molecules on a (1×3) reconstructed surface, dehydrogenated molecules with two hydrogen atoms detached from one amino group (-2H-DAT) on a (1×5) reconstructed surface and dehydrogenated molecules with four hydrogen atoms detached from two amino groups (-4H-DAT) on a (1×3) reconstructed surface through N-Au bonds. Furthermore, after annealing the sample to 350 ℃, STM image shows only one self-assembled structure with -4H-DAT molecules on a (1×3) reconstructed surface. Relative STM simulations of different self-assembled structures show excellent agreements with the experimental STM images at different annealing temperatures. Further DFT calculations on the dehydrogenation process of DAT molecule prove that the dehydrogenation barrier on a (1×5) reconstructed surface is lower than that on (1×3) one, which demonstrate the experimental results that the formation temperature of a (1×3) reconstructed surface is higher than that of a (1×5) one.

A facile and efficient dry transfer technique for two-dimensional Van der Waals heterostructure Hot!

Li Xie(谢立), Luojun Du(杜罗军), Xiaobo Lu(卢晓波), Rong Yang(杨蓉), Dongxia Shi(时东霞), Guangyu Zhang(张广宇)
Chin. Phys. B, 2017, 26 (8): 087306 doi: 10.1088/1674-1056/26/8/087306
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Two-dimensional (2D) Van der Waals heterostructures have aroused extensive concerns in recent years. Their fabrication calls for facile and efficient transfer techniques for achieving well-defined structures. In this work, we report a simple and effective dry transfer method to fabricate 2D heterostructures with a clean interface. Using Propylene Carbonate (PC) films as stamps, we are able to pick up various 2D materials flakes from the substrates and unload them to the receiving substrates at an elevated temperature. Various multilayer heterostructures with ultra-clean interfaces were fabricated by this technique. Furthermore, the 2D materials can be pre-patterned before transfer so as to fabricate desired device structures, demonstrating a facile way to promote the development of 2D heterostructures.

Electronic structure and nematic phase transition in superconducting multiple-layer FeSe films grown by pulsed laser deposition method Hot!

Bing Shen(沈兵), Zhong-Pei Feng(冯中沛), Jian-Wei Huang(黄建伟), Yong Hu(胡勇), Qiang Gao(高强), Cong Li(李聪), Yu Xu(徐煜), Guo-Dong Liu(刘国东), Li Yu(俞理), Lin Zhao(赵林), Kui Jin(金魁), X J Zhou(周兴江)
Chin. Phys. B, 2017, 26 (7): 077402 doi: 10.1088/1674-1056/26/7/077402
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We report comprehensive angle-resolved photoemission investigations on the electronic structure of single crystal multiple-layer FeSe films grown on CaF2 substrate by pulsed laser deposition (PLD) method. Measurements on FeSe/CaF2 samples with different superconducting transition temperatures Tc of 4 K, 9 K, and 14 K reveal electronic difference in their Fermi surface and band structure. Indication of the nematic phase transition is observed from temperature-dependent measurements of these samples; the nematic transition temperature is 140–160 K, much higher than~90 K for the bulk FeSe. Potassium deposition is applied onto the surface of these samples; the nematic phase is suppressed by potassium deposition which introduces electrons to these FeSe films and causes a pronounced electronic structure change. We compared and discussed the electronic structure and superconductivity of the FeSe/CaF2 films by PLD method with the FeSe/SrTiO3 films by molecular beam epitaxy (MBE) method and bulk FeSe. The PLD-grown multilayer FeSe/CaF2 is more hole-doped than that in MBE-grown multiple-layer FeSe films. Our results on FeSe/CaF2 films by PLD method establish a link between bulk FeSe single crystal and FeSe/SrTiO3 films by MBE method, and provide important information to understand superconductivity in FeSe-related systems.

Asymmetrical plasmon reflections in tapered graphene ribbons with wrinkle edges Hot!

Cui Yang(杨翠), Runkun Chen(陈闰堃), Yuping Jia(贾玉萍), Liwei Guo(郭丽伟), Jianing Chen(陈佳宁)
Chin. Phys. B, 2017, 26 (7): 074220 doi: 10.1088/1674-1056/26/7/074220
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Asymmetrical graphene plasmon reflection patterns are found in infrared near-field images of tapered graphene ribbons epitaxially grown on silicon carbon substrates. Comparing experimental data with numerical simulations, the asymmetry of these patterns is attributed to reflection of plasmons by wrinkled edges naturally grown in the graphene. These graphene wrinkles are additional plasmon reflectors with varying optical conductivity, which act as nanometer scale plasmonic modulators and thus have potential applications in photoelectric information detectors, transmitters, and modulators.

Feedback arcs and node hierarchy in directed networks Hot!

Jin-Hua Zhao(赵金华), Hai-Jun Zhou(周海军)
Chin. Phys. B, 2017, 26 (7): 078901 doi: 10.1088/1674-1056/26/7/078901
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Directed networks such as gene regulation networks and neural networks are connected by arcs (directed links). The nodes in a directed network are often strongly interwound by a huge number of directed cycles, which leads to complex information-processing dynamics in the network and makes it highly challenging to infer the intrinsic direction of information flow. In this theoretical paper, based on the principle of minimum-feedback, we explore the node hierarchy of directed networks and distinguish feedforward and feedback arcs. Nearly optimal node hierarchy solutions, which minimize the number of feedback arcs from lower-level nodes to higher-level nodes, are constructed by belief-propagation and simulated-annealing methods. For real-world networks, we quantify the extent of feedback scarcity by comparison with the ensemble of direction-randomized networks and identify the most important feedback arcs. Our methods are also useful for visualizing directed networks.

A low cost composite quasi-solid electrolyte of LATP, TEGDME, and LiTFSI for rechargeable lithium batteries Hot!

Jie Huang(黄杰), Jia-Yue Peng(彭佳悦), Shi-Gang Ling(凌仕刚), Qi Yang(杨琪), Ji-Liang Qiu(邱纪亮), Jia-Ze Lu(卢嘉泽), Jie-Yun Zheng(郑杰允), Hong Li(李泓), Li-Quan Chen(陈立泉)
Chin. Phys. B, 2017, 26 (6): 068201 doi: 10.1088/1674-1056/26/6/068201
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The composite quasi solid state electrolytes (CQSE) is firstly synthesized with quasi solid state electrolytes (QSE) and lithium-ion-conducting material Li1.4Al0.4Ti1.6(PO4)3 (LATP), and the QSE consists of[LiG4][TFSI] with fumed silica nanoparticles. Compared with LATP, CQSE greatly improves the interface conductance of solid electrolytes. In addition,it has lower liquid volume relative to QSE. Although the liquid volume fraction of CQSE drops to 60%, its conductivity can also reach 1.39×10-4 s/cm at 20℃. Linear sweep voltammetry (LSV) is conducted on each composite electrolyte. The results show the possibility that CQSE has superior electrochemical stability up to 5.0 V versus Li/Li+1. TG curves also show that composite electrolytes have higher thermal stability. In addition, the performance of Li/QSE/LiMn2O4 cells and Li/CQSE/LiMn2O4 is evaluated and shows good electrochemical characteristics at 60℃.

Different angle-resolved polarization configurations of Raman spectroscopy: A case on the basal and edge plane of two-dimensional materials Hot!

Xue-Lu Liu(刘雪璐), Xin Zhang(张昕), Miao-Ling Lin(林妙玲), Ping-Heng Tan(谭平恒)
Chin. Phys. B, 2017, 26 (6): 067802 doi: 10.1088/1674-1056/26/6/067802
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Angle-resolved polarized Raman (ARPR) spectroscopy can be utilized to assign the Raman modes based on crystal symmetry and Raman selection rules and also to characterize the crystallographic orientation of anisotropic materials. However, polarized Raman measurements can be implemented by several different configurations and thus lead to different results. In this work, we systematically analyze three typical polarization configurations:1) to change the polarization of the incident laser, 2) to rotate the sample, and 3) to set a half-wave plate in the common optical path of incident laser and scattered Raman signal to simultaneously vary their polarization directions. We provide a general approach of polarization analysis on the Raman intensity under the three polarization configurations and demonstrate that the latter two cases are equivalent to each other. Because the basal plane of highly ordered pyrolytic graphite (HOPG) exhibits isotropic feature and its edge plane is highly anisotropic, HOPG can be treated as a modelling system to study ARPR spectroscopy of two-dimensional materials on their basal and edge planes. Therefore, we verify the ARPR behaviors of HOPG on its basal and edge planes at three different polarization configurations. The orientation direction of HOPG edge plane can be accurately determined by the angle-resolved polarization-dependent G mode intensity without rotating sample, which shows potential application for orientation determination of other anisotropic and vertically standing two-dimensional materials and other materials.

Transition from tunneling regime to local point contact realized on Ba0.6K0.4Fe2As2 surface Hot!

Xingyuan Hou(侯兴元), Yunyin Jie(揭云印), Jing Gong(巩靖), Bing Shen(沈冰), Hai Zi(子海), Chunhong Li(李春红), Cong Ren(任聪), Lei Shan(单磊)
Chin. Phys. B, 2017, 26 (6): 067402 doi: 10.1088/1674-1056/26/6/067402
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Using scanning tunneling spectroscopy, we studied the transition from tunneling regime to local point contact on the iron-based superconductor Ba0.6K0.4Fe2As2. By gradually reducing the junction resistance, a series of spectra were obtained with the characteristics evolving from single-particle tunneling into Andreev reflection. The spectra can be well fitted to the modified Blonder-Tinkham-Klapwijk (BTK) model and exhibit significant changes of both spectral broadening and orbital selection due to the formation of point contact. The spatial resolution of the point contact was estimated to be several nanometers, providing a unique way to study the inhomogeneity of unconventional superconductors on such a scale.

Doping Mn into (Li1-xFex)OHFe1-ySe superconducting crystals via ion-exchange and ion-release/introduction syntheses Hot!

Huaxue Zhou(周花雪), Shunli Ni(倪顺利), Jie Yuan(袁洁), Jun Li(李军), Zhongpei Feng(冯中沛), Xingyu Jiang(江星宇), Yulong Huang(黄裕龙), Shaobo Liu(刘少博), Yiyuan Mao(毛义元), Fang Zhou(周放), Kui Jin(金魁), Xiaoli Dong(董晓莉), Zhongxian Zhao(赵忠贤)
Chin. Phys. B, 2017, 26 (5): 057402 doi: 10.1088/1674-1056/26/5/057402
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We report the success in introducing Mn into (Li1-xFex)OHFe1-ySe superconducting crystals by applying two different hydrothermal routes, ion exchange (1-step) and ion release/introduction (2-step). The micro-region x-ray diffraction and energy dispersive x-ray spectroscopy analyses indicate that Mn has been doped into the lattice, and its content in the 1-step fabricated sample is higher than that in the 2-step one. Magnetic susceptibility and electric transport properties reveal that Mn doping influences little on the superconducting transition, regardless of 1-step or 2-step routes. By contrast, the characteristic temperature T*, at which the negative Hall coefficient reaches its minimum, is significantly reduced by Mn doping. This implies that the hole carriers contribution is obviously modified, and hence the hole band might have no direct relationship with the superconductivity in (Li1-xFex)OHFe1-ySe superconductors. Our present hydrothermal methods of ion exchange and ion release/introduction provide an efficient way for elements substitution/doping into (Li1-xFex)OHFe1-ySe superconductors, which will promote the in-depth investigations on the role of multiple electron and hole bands and their interplay with the high-temperature superconductivity in the FeSe-based superconductors.

Bow shocks formed by a high-speed laser-driven plasma cloud interacting with a cylinder obstacle Hot!

Yan-Fei Li(李彦霏), Yu-Tong Li(李玉同), Da-Wei Yuan(袁大伟), Fang Li(李芳), Bao-Jun Zhu(朱保君), Zhe Zhang(张喆), Jia-Yong Zhong(仲佳勇), Bo Han(韩波), Hui-Gang Wei(魏会冈), Xiao-Xing Pei(裴晓星), Jia-Rui Zhao(赵家瑞), Chang Liu(刘畅), Xiao-Xia Yuan(原晓霞), Guo-Qian Liao(廖国前), Yong-Joo Rhee, Xin Lu(鲁欣), Neng Hua(华能), Bao-Qiang Zhu(朱宝强), Jian-Qiang Zhu(朱健强), Zhi-Heng Fang(方智恒), Xiu-Guang Huang(黄秀光), Si-Zu Fu(傅思祖), Gang Zhao(赵刚), Jie Zhang(张杰)
Chin. Phys. B, 2017, 26 (5): 055202 doi: 10.1088/1674-1056/26/5/055202
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A bow shock is formed in the interaction of a high-speed laser-driven plasma cloud with a cylinder obstacle. Its temporal and spatial structures are observed by shadowgraphy and interferometry. The width of the shock transition region is ~ 50 μm, comparable to the ion-ion collision mean free path, which indicates that collision is dominated in the shock probably. The Mach-number of the ablating plasma cloud is ~ 15 at first, and decreases with time resulting in a changing shock structure. A two-dimension hydrodynamics code, USim, is used to simulate the interaction process. The simulated shocks can well reproduce the observed.

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