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117 results on '"Chen, Gen"'

1. Anisotropic $s$-wave gap in the vicinity of a quantum critical point in superconducting BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_2$ single crystals: a study of point-contact spectroscopy

Author

Zhan, Hong-xing, primary, Lin, Yu-chi, additional, Zhao, Yu-qing, additional, Zuo, Hai-yan, additional, Wang, Xing-yu, additional, Ma, Xiao-yan, additional, Li, Chun-hong, additional, Luo, Hui-qian, additional, Chen, Gen-fu, additional, Li, Shi-liang, additional, and Ren, Cong, additional

Published
2024
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14. Emergence of Superconductivity on the Border of Antiferromagnetic Order in RbMn6Bi5 under High Pressure: A New Family of Mn-Based Superconductors.

Author

Yang, Peng-Tao, 杨, 芃焘, Dong, Qing-Xin, č'Ł, 庆新, Shan, Peng-Fei, 单, 鹏飞, Liu, Zi-Yi, 刘, ĺ-ĺ„€, Sun, Jian-Ping, ĺ-™, 建平, Dun, Zhi-Ling, 顿, 志凌, Uwatoko, Yoshiya, Chen, Gen-Fu, 陈, 根富, Wang, Bo-Sen, 王, é"‚森, Cheng, Jin-Guang, and 程, é‡'ĺ...‰

Subjects
SUPERCONDUCTIVITY, SUPERCONDUCTORS, MAGNETIC measurements, MAGNETIC susceptibility, ALKALI metals
Abstract

We report the discovery of superconductivity on the border of antiferromagnetic order in a quasi-one-dimensional material RbMn6Bi5 via measurements of resistivity and magnetic susceptibility under high pressures. Its phase diagram of temperature versus pressure resembles those of many magnetism-mediated superconducting systems. With increasing pressure, its antiferromagnetic ordering transition with T N = 83 K at ambient pressure is first enhanced moderately and then suppressed completely at a critical pressure of P c ≈ 13 GPa, around which bulk superconductivity emerges and exhibits a dome-like T c(P) with a maximal T c onset ≈ 9.5 K at about 15 GPa. In addition, the superconducting state around P c is characterized by a large upper critical field μ 0 H c2(0) exceeding the Pauli paramagnetic limit, implying a possible unconventional paring mechanism. The present study, together with our recent work on KMn6Bi5 (the maximum T c onset ≈ 9.3 K), makes A Mn6Bi5 (A = alkali metal) a new family of Mn-based superconductors with relatively high T c. [ABSTRACT FROM AUTHOR]

Published
2022
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17. Interface design of the blanket system for CFETR

Author

Lei, Mingzhun, primary, Song, Yuntao, additional, Ni, Xiaojun, additional, Wu, Xinghua, additional, Shen, Junsong, additional, Liu, Sumei, additional, Liu, Songlin, additional, Wang, Xiaoyu, additional, Cheng, Yong, additional, Xie, Yuanlai, additional, Wang, Xiaojie, additional, Liu, Liang, additional, Chen, Gen, additional, Xu, Tiejun, additional, and Lu, Kun, additional

Published
2020
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20. Superconductivity with a Violation of Pauli Limit and Evidences for Multigap in η -Carbide Type Ti4Ir2O.

Author

Ruan, Bin-Bin, Zhou, Meng-Hu, Yang, Qing-Song, Gu, Ya-Dong, Ma, Ming-Wei, Chen, Gen-Fu, and Ren, Zhi-An

Subjects
SUPERCONDUCTIVITY, FERMI surfaces, ELECTRON configuration, SPIN-orbit interactions, FERMI level
Abstract

We report the synthesis, crystal structure, and superconductivity of Ti4Ir2O. The title compound crystallizes in an η -carbide type structure of the space group F d 3 ÂŻ m (No. 227), with lattice parameters a = b = c = 11.6194(1) Ă.... The superconducting temperature T c is found to be 5.1â€"5.7 K. Most surprisingly, Ti4Ir2O hosts an upper critical field of 16.45 T, which is far beyond the Pauli paramagnetic limit. Strong coupled superconductivity with evidences for multigap is revealed by the measurements of heat capacity and upper critical field. First-principles calculations suggest that the density of states near the Fermi level originates from the hybridization of Ti-3 d and Ir-5 d orbitals, and the effect of spin-orbit coupling on the Fermi surfaces is prominent. Large values of the Wilson ratio (R W ∼ 3.9), the Kadowakiâ€"Woods ratio [ A / Îł 2 ∼ 9.0 Ă— 10âˆ'6 μΩâ‹...cm/(mJâ‹...molâˆ'1â‹...Kâˆ'1)2], and the Sommerfeld coefficient (Îł = 33.74 mJâ‹...molâˆ'1â‹...Kâˆ'2) all suggest strong electron correlations (similar to heavy fermion systems) in Ti4Ir2O. The violation of Pauli limit is possibly due to a combination of strong-coupled superconductivity and large spin-orbit scattering. With these intriguing behaviors, Ti4Ir2O serves as a candidate for unconventional superconductor. [ABSTRACT FROM AUTHOR]

Published
2022
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24. Pressure-Induced Metallization and Structural Phase Transition in the Quasi-One-Dimensional TlFeSe2*

Author

Liu, Zi-Yi, primary, Dong, Qing-Xin, additional, Shan, Peng-Fei, additional, Wang, Yi-Yan, additional, Dai, Jian-Hong, additional, Jana, Rajesh, additional, Chen, Ke-Yu, additional, Sun, Jian-Ping, additional, Wang, Bo-Sen, additional, Yu, Xiao-Hui, additional, Liu, Guang-Tong, additional, Uwatoko, Yoshiya, additional, Sui, Yu, additional, Yang, Huai-Xin, additional, Chen, Gen-Fu, additional, and Cheng, Jin-Guang, additional

Published
2020
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27. Commissioning of RF system of the 200 MeV proton cyclotron

Author

Chen, Gen, primary, Liu, Guang, additional, Zhao, Yanping, additional, Peng, Zhen, additional, Zhang, Xin, additional, Chao, Chujie, additional, Long, Xuyun, additional, Yu, Chuansong, additional, Karamyshev, Oleg, additional, Karamysheva, Galina, additional, Shirkov, Grigori, additional, Caruso, Antonio, additional, and Calabretta, Luciano, additional

Published
2019
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28. Substitution effect on the superconductivity in Mo3–xRexAl2C with β-Mn structure prepared by microwave method.

Author

Sun, Jun-Nan, Ruan, Bin-Bin, Zhou, Meng-Hu, Chen, Yin, Yang, Qing-Song, Shan, Lei, Ma, Ming-Wei, Chen, Gen-Fu, and Ren, Zhi-An

Subjects
SUPERCONDUCTIVITY, MICROWAVES, LATTICE constants, SUPERCONDUCTORS
Abstract

We report the microwave synthesis and the doping effect of Mo3−xRexAl2C (0 ≤ x ≤ 0.3) superconductor. Re doping into Mo3Al2C results in a regular shrinkage of the lattice, marked by the linear decrease of lattice parameter a from 6.868(1) Ĺ (for Mo3Al2C) to 6.846(2) Ĺ (for Mo2.7Re0.3Al2C). Upon Re doping, Tc of Mo3−xRexAl2C first increases and then decreases, with the maximum Tc = 9.14 K at the optimal doping level of x = 0.09. Our report provides a convenient method to synthesize Mo3−xRexAl2C within minutes, and also marks the first Re doping study with enhanced superconductivity on the non-centrosymmetric superconductor Mo3Al2C. [ABSTRACT FROM AUTHOR]

Published
2021
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29. Design and analysis of the cold cathode ion source for 200 MeV superconducting cyclotron

Author

Xu, Shiwen, Calabretta, Luciano, Chen, Gen, Karamyshev, Oleg, Karamysheva, Galina, Shirkov, Grigori, and Xu, Manman

Subjects
Electromagnetic field, History, Test bench, Materials science, Cyclotron, Electron, Ion source, Accelerator Physics, Computer Science Applications, Education, law.invention, MC3: Novel Particle Sources and Acceleration Techniques, Physics::Plasma Physics, law, Electric field, Secondary emission, Hot-filament ionization gauge, Physics::Accelerator Physics, Atomic physics
Abstract

SC200 is a superconducting isochronous cyclotron which generates 200 MeV, 400 nA proton beam for particle therapy. The cold-cathode-type Penning ion gauge (PIG) ion source for the internal ion source of SC200 has been selected as an alternative and preliminary designed. In this paper, design of ion source and test bench are demonstrated. Currently, the properties of ion source have been simulated for a variety of electric field distributions and magnetic field strengths. The secondary electron emission in electromagnetic field has been simulated. It provides reference for the optimization design of arc chamber. In addition, the sample of cold-cathode-type ion source has been tested on the test bench and extracted beam intensity has been measured over 200 μA., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Published
2019

33. Experimental observation of enhanced plasma potential due to unabsorbed fast wave on EAST

Author

Zhang, Xinjun, primary, Liu, Lunan, additional, Qin, Chengming, additional, Lin, Y., additional, Ochoukov, R., additional, Zhao, Yanping, additional, Jean-Marie, Noterdaeme, additional, Wukitch, Steve, additional, Gong, X.Z., additional, Wan, B.N., additional, Song, Y.T., additional, Yuan, Shuai, additional, Yang, Hua, additional, Mao, Yuzhou, additional, Cheng, Yan, additional, Wang, Lei, additional, Deng, Xu, additional, Chen, Gen, additional, Ju, Songqing, additional, Zhang, Kai, additional, and Ping, Lanlan, additional

Published
2019
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36. Tip-induced superconductivity commonly existing in the family of transition-metal dipnictides MPn2.

Author

Zhang, Meng-Di, Xu, Sheng, Hou, Xing-Yuan, Gu, Ya-Dong, Zhang, Fan, Xia, Tian-Long, Ren, Zhi-An, Chen, Gen-Fu, Hao, Ning, and Shan, Lei

Subjects
SEMIMETALS, SUPERCONDUCTIVITY, FERROMAGNETISM
Abstract

We report the tip-induced superconductivity on the topological semimetal NbSb2, similar to the observation on TaAs2 and NbAs2. Belonging to the same family of MPn2, all these materials possess similar band structures, indicating that the tip-induced superconductivity may be closely related to their topological nature and share a common mechanism. Further analysis suggests that a bulk band should play the dominant role in such local superconductivity most likely through interface coupling. In addition, the compatibility between the induced superconductivity and tips' ferromagnetism gives an evidence for its unconventional nature. These results provide further clues to elucidate the mechanism of the tip-induced superconductivity observed in topological materials. [ABSTRACT FROM AUTHOR]

Published
2021
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37. Pressure-Dependent Point-Contact Spectroscopy of Superconducting PbTaSe2 Single Crystals.

Author

Zi, Hai, Zhao, Ling-Xiao, Hou, Xing-Yuan, Shan, Lei, Ren, Zhian, Chen, Gen-Fu, and Ren, Cong

Subjects
SINGLE crystals, SPECTROMETRY, BAND gaps, CRITICAL temperature, ELECTRON pairs
Abstract

We develop an experimental tool to investigate the order parameter of superconductors by combining point-contact spectroscopy measurement with high-pressure technique. It is demonstrated for the first time that planar point-contact spectroscopy measurement on noncentrosymmetric superconducting PbTaSe2 single crystals is systematically subjected to hydrostatic pressures up to 12.1 kbar. Under such a high pressure, the normal-state contact resistance is sensitive to the applied pressure, reflecting the underlying variation of contact transparency upon pressures. In a superconducting state, the pressure dependence of the energy gap Δ0 and the critical temperature Tc for gap opening/closing are extracted based on a generalized Blond–Tinkham–Klapwijk model. The gap ratio 2Δ0/kBTc indicates a crossover from weak coupling to strong coupling in electron pairing strength upon pressure for PbTaSe2. Our experimental results show the accessibility and validity of high-pressure point-contact spectroscopy, offering rich information about high-pressure superconductivity. [ABSTRACT FROM AUTHOR]

Published
2020
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38. A New Quasi-One-Dimensional Ternary Molybdenum Pnictide Rb2Mo3As3 with Superconducting Transition at 10.5K.

Author

Zhao, Kang, Mu, Qing-Ge, Ruan, Bin-Bin, Zhou, Meng-Hu, Yang, Qing-Song, Liu, Tong, Pan, Bo-Jin, Zhang, Shuai, Chen, Gen-Fu, and Ren, Zhi-An

Subjects
SUPERCONDUCTING transitions, IRON-based superconductors, ELECTRICAL resistivity, MOLYBDENUM, X-ray powder diffraction, LATTICE constants
Abstract

We report superconductivity in a new ternary molybdenum pnictide Rb2Mo3As3, synthesized via the solid state reaction method. Powder x-ray diffraction analysis reveals a hexagonal crystal structure with space group (No. 187), and the refined lattice parameters are a = 10.431(5) Ĺ, c = 4.460(4) Ĺ. SEM images show rod-like grains with good ductility, confirming a quasi-one-dimensional (Q1D) structure. Electrical resistivity and dc magnetic susceptibility characterizations exhibit superconductivity with an onset of Tc = 10.5 K. The upper critical field of Rb2Mo3As3 is estimated to be 28.2T at zero temperature, providing an evidence of possible unconventional superconductivity. Our recent discovery of MoAs-based superconductors above 10 K provides a unique platform for the study of exotic superconductivity in 4d electron systems with Q1D crystal structures. [ABSTRACT FROM AUTHOR]

Published
2020
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39. Research and Development of RF system for SC200 cyclotron

Author

Chen, Gen, Calabretta, Luciano, Caruso, Antonio, Chao, Chujie, Karamyshev, Oleg, Karamysheva, Galina, Liu, Guang, Long, Xuyun, Morozov, Nikolay, Peng, Zhen, Samsonov, Evgeny, Shirkov, Grigori, Song, Yuntao, Wang, Yongsheng, Wei, Chuansong, Xu, Manman, Yang, Qingxi, Zhang, Xin, and Zhao, Yanping

Subjects
Physics, History, business.industry, Cyclotron, Electrical engineering, T06 Room Temperature RF, Acceleration voltage, Accelerator Physics, Computer Science Applications, Education, law.invention, Acceleration, Amplitude, 07 Accelerator Technology, law, Q factor, Harmonic, Radio frequency, business, Proton therapy
Abstract

A 200MeV compact isochronous superconducting cyclotron, named SC200, for proton therapy is under development by collaboration of ASIPP (Hefei, China) and JINR (Dubna, Russia). The radio frequency (RF) system as one of most significant subsystems in cyclotron consists of acceleration cavity, low level RF, RF source and transmission network. SC200 has two cavities connected in the centre, which are operated at 91.5 MHz with second harmonic. To meet the required acceleration voltage, the cavities have been carefully designed with comprised choices between several aspects, such as Q factor, mechanic stability and so on. The low-level RF (LLRF) system has been implemented by using the FPGA to achieve the significant accelerating voltage with an amplitude stability of, Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Published
2018

40. Pressure-Induced Metallization and Structural Phase Transition in the Quasi-One-Dimensional TlFeSe2.

Author

Liu, Zi-Yi, Dong, Qing-Xin, Shan, Peng-Fei, Wang, Yi-Yan, Dai, Jian-Hong, Jana, Rajesh, Chen, Ke-Yu, Sun, Jian-Ping, Wang, Bo-Sen, Yu, Xiao-Hui, Liu, Guang-Tong, Uwatoko, Yoshiya, Sui, Yu, Yang, Huai-Xin, Chen, Gen-Fu, and Cheng, Jin-Guang

Subjects
METAL-insulator transitions, PHASE transitions, TRANSITION metals, SUPERCONDUCTIVITY, TERNARY system, SINGLE crystals
Abstract

We report a comprehensive high-pressure study on the monoclinic TlFeSe2 single crystal, which is an antiferromagnetic insulator with quasi-one-dimensional crystal structure at ambient pressure. It is found that TlFeSe2 undergoes a pressure-induced structural transformation from the monoclinic phase to an orthorhombic structure above Pc ≈ 13 GPa, accompanied with a large volume collapse of ΔV/V0 = 8.3%. In the low-pressure monoclinic phase, the insulating state is easily metallized at pressures above 2 GPa; while possible superconductivity with K is found to emerge above 30 GPa in the high-pressure phase. Such a great tunability of TlFeSe2 under pressure indicates that the ternary AFeSe2 system (A = Tl, K, Cs, Rb) should be taken as an important platform for explorations of interesting phenomena such as insulator-metal transition, dimensionality crossover, and superconductivity. [ABSTRACT FROM AUTHOR]

Published
2020
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42. Recent ICRF coupling experiments on EAST

Author

YANG, Yuqing, primary, ZHANG, Xinjun, additional, ZHAO, Yanping, additional, QIN, Chengming, additional, CHENG, Yan, additional, MAO, Yuzhou, additional, YANG, Hua, additional, WANG, Jianhua, additional, YUAN, Shuai, additional, WANG, Lei, additional, JU, Songqing, additional, CHEN, Gen, additional, DENG, Xu, additional, ZHANG, Kai, additional, WAN, Baonian, additional, LI, Jiangang, additional, SONG, Yuntao, additional, GONG, Xianzu, additional, QIAN, Jinping, additional, and ZHANG, Tao, additional

Published
2018
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47. High Power RF Transmitters for ICRF Applications on EAST

Author

Zhao Yanping, Chen Gen, Wang Lei, Yuan Shuai (袁帅), Zhang Xinjun, Cheng Yan(程艳), Mao Yuzhou, Ryuhei Kumazawa, Deng Xu, Lei Ye, JU Songqing (琚松青), and Qin Chengming

Subjects
Dummy load, Radio transmitter design, Materials science, business.industry, Amplifier, Transmitter, RF power amplifier, Electrical engineering, High voltage, Tetrode, Radio frequency, Condensed Matter Physics, business
Abstract

An Ion Cyclotron Range of Frequency (ICRF) system with a radio frequency (RF) power of 4 × 1.5 MW was developed for the Experimental Advanced Superconducting Tokamak (EAST). High RF power transmitters were designed as a part of the research and development (R&D) for an ICRF system with long pulse operation at megawatt levels in a frequency range of 25 MHz to 70 MHz. Studies presented in this paper cover the following parts of the high power transmitter: the three staged high power amplifier, which is composed of a 5 kW wideband solid state amplifier, a 100 kW tetrode drive stage amplifier and a 1.5 MW tetrode final stage amplifier, and the DC high voltage power supply (HVPS). Based on engineering design and static examinations, the RF transmitters were tested using a matched dummy load where an RF output power of 1.5 MW was achieved. The transmitters provide 6 MW RF power in primary phase and will reach a level up to 12 MW after a later upgrade. The transmitters performed successfully in stable operations in EAST and HT-7 devices. Up to 1.8 MW of RF power was injected into plasmas in EAST ICRF heating experiments during the 2010 autumn campaign and plasma performance was greatly improved.

Published
2013

48. Pseudogap and Superconducting Gap in Sm FeAs(O 1-x F x ) Superconductor from Photoemission Spectroscopy

Author

Chen Xian-Hui, Dong Xiao-Li, Zhao Zhong-Xian, Liu Guo-Dong, Meng Jian-Qiao, Wang Xiaoyang, Zhou Yong, Liu Hai-Yun, Wu Gang, Zhang Wen-Tao, Yi Wei, Chen Gen-Fu, Che Guang-Can, Zhou Xing-Jiang, Zhao Lin, Chen Chuang-Tian, Wang Nan-Lin, Zhu Yong, Liu Rong-Hua, Jia Xiao-Wen, Wang Guiling, Ren Zhi-An, and XU Zu-Yan

Subjects
Superconductivity, Materials science, Condensed matter physics, Electrical resistivity and conductivity, Photoemission spectroscopy, Band gap, Condensed Matter::Superconductivity, General Physics and Astronomy, Condensed Matter::Strongly Correlated Electrons, Angle-resolved photoemission spectroscopy, Spectroscopy, Pseudogap, Spectral line
Abstract

High resolution photoemission measurements are carried out on non-superconducting SmOFeAs parent compound and superconducting SmFeAs(O1-xFx) (x = 0.12, and 0.15) compounds. The momentum-integrated spectra exhibit a clear Fermi cutoff that shows little leading-edge shift in the superconducting state. A robust feature at 13meV is identified in all these samples. Spectral weight suppression near Ef with decreasing temperature is observed in both undoped and doped samples that points to a possible existence of a pseudogap in these Fe-based compounds.

Published
2008

49. Element Substitution Effect in Transition Metal Oxypnictide Re(O 1- x F x )TAs (Re = rare earth, T = transition metal)

Author

Zheng Ping, Chen Gen-Fu, Wu Dan, Luo Jian-Lin, Li Zheng, Dong Jing, Wang Nan-Lin, Li Gang, and Hu Wan-Zheng

Subjects
Superconductivity, Materials science, Condensed matter physics, General Physics and Astronomy, Crystal structure, Metal, Tetragonal crystal system, Crystallography, Ferromagnetism, Transition metal, Oxypnictide, Electrical resistivity and conductivity, visual_art, visual_art.visual_art_medium
Abstract

Different element substitution effects in transition metal oxypnictide Re(O1-xFx)TAs, with Re = La, Ce, Nd, Eu, Gd, Tm, T = Fe, Ni, Ru, are studied. Similar to the La- or Ce-based systems, we find that the pure NdOFeAs shows a strong resistivity anomaly near 145 K, which is ascribed to the spin-density-wave instability. Electron doping by F increases Tc to about 50 K. While in the case of Gd, Tc is reduced below 10 K. The tetragonal ZrCuSiAs-type structure could not be formed for Eu or Tm substitution in our preparing process. For the Ni-based case, although both pure and F-doped LaONiAs are superconducting, no superconductivity is found when La is replaced by Ce in both the cases, instead a ferromagnetic ordering transition is likely to form at low temperature in the undoped sample. We also synthesize LaO1-xFxRuAs and CeO1-xFxRuAs compounds. The metallic behaviour is observed down to 4K.

Published
2008

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