41 results on '"Yunkun Yang"'
Search Results
2. Low-pass filters based on van der Waals ferromagnets
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Zihan Li, Shanshan Liu, Jiabao Sun, Jiayi Zhu, Yanhui Chen, Yunkun Yang, Linfeng Ai, Enze Zhang, Ce Huang, Pengliang Leng, Minhao Zhao, Xiaoyi Xie, Yuda Zhang, Nesta Benno Joseph, Rajdeep Banerjee, Awadhesh Narayan, Jin Zou, Wenqing Liu, Xiaodong Xu, and Faxian Xiu more...
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Electrical and Electronic Engineering ,Instrumentation ,Electronic, Optical and Magnetic Materials - Published
- 2023
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Catalog
3. 3D狄拉克半金属(Cd1−xZnx)3As2/Sb2Se3 背对背异质结用于超高信噪比的高速宽光谱光电探测器
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Xingchao Zhang, Yunkun Yang, Hongxi Zhou, Xianchao Liu, Rui Pan, He Yu, Jun Gou, Zhiming Wu, Jiang Wu, Faxian Xiu, Yi Shi, and Jun Wang
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General Materials Science - Published
- 2022
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4. Photodetection and Infrared Imaging Based on Cd3As2 Epitaxial Vertical Heterostructures
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Yunkun Yang, Junchen Zhou, Xiaoyi Xie, Xingchao Zhang, Zihan Li, Shanshan Liu, Linfeng Ai, Qiang Ma, Pengliang Leng, Minhao Zhao, Jun Wang, Yi Shi, and Faxian Xiu
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General Engineering ,General Physics and Astronomy ,General Materials Science - Published
- 2022
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5. Observation of thickness-tuned universality class in superconductingβ-Wthin films
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Linfeng Ai, Shanshan Liu, Haiwen Liu, Enze Zhang, Shaozhi Deng, Jinglei Zhang, Minhao Zhao, Yong Zhang, Lun Li, Xingwang Xie, Junjie Qi, Ce Huang, Zihan Li, Xiaoyi Xie, Xufeng Kou, Faxian Xiu, Yunkun Yang, Ya-Qing Bie, and Runze Zhan more...
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Physics ,Superconductivity ,Quantum phase transition ,Phase transition ,Multidisciplinary ,Condensed matter physics ,Renormalization group ,010502 geochemistry & geophysics ,01 natural sciences ,Magnetic field ,Universality (dynamical systems) ,Quantum ,Scaling ,0105 earth and related environmental sciences - Abstract
The interplay between quenched disorder and critical behavior in quantum phase transitions is conceptually fascinating and of fundamental importance for understanding phase transitions. However, it is still unclear whether or not the quenched disorder influences the universality class of quantum phase transitions. More crucially, the absence of superconducting-metal transitions under in-plane magnetic fields in 2D superconductors imposes constraints on the universality of quantum criticality. Here, we observe the thickness-tuned universality class of superconductor-metal transition by changing the disorder strength in β - W films with varying thickness. The finite-size scaling uncovers the switch of universality class: quantum Griffiths singularity to multiple quantum criticality at a critical thickness of t c ⊥ 1 ~ 8 n m and then from multiple quantum criticality to single criticality at t c ⊥ 2 ~ 16 n m . Moreover, the superconducting-metal transition is observed for the first time under in-plane magnetic fields and the universality class is changed at t c ‖ ~ 8 n m . The observation of thickness-tuned universality class under both out-of-plane and in-plane magnetic fields provides broad information for the disorder effect on superconducting-metal transitions and quantum criticality. more...
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- 2021
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6. Semiconductorlike photocarrier dynamics in Dirac-semimetal Cd3As2 films probed with transient terahertz spectroscopy
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Wenjie Zhang, Yunkun Yang, Peng Suo, Kaiwen Sun, Jun Peng, Xian Lin, Faxian Xiu, and Guohong Ma
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- 2022
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7. Photodetection and Infrared Imaging Based on Cd
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Yunkun, Yang, Junchen, Zhou, Xiaoyi, Xie, Xingchao, Zhang, Zihan, Li, Shanshan, Liu, Linfeng, Ai, Qiang, Ma, Pengliang, Leng, Minhao, Zhao, Jun, Wang, Yi, Shi, and Faxian, Xiu
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Due to the nontrivial electronic structure, Cd
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- 2022
8. Gate-Tunable Surface States in Topological Insulator β-Ag2Te with High Mobility
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Yuxiang Wang, Junchen Zhou, Xiaoyi Xie, Yaozhi Yang, Xuandong Sun, Linfeng Ai, Faxian Xiu, Yunkun Yang, Pengliang Leng, Ce Huang, Zihan Li, Xiangyu Cao, Fangting Chen, and Enze Zhang
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Condensed Matter::Quantum Gases ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Bioengineering ,02 engineering and technology ,General Chemistry ,Quantum phases ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Topological insulator ,General Materials Science ,0210 nano-technology ,Surface states - Abstract
Stimulated by novel properties in topological insulators, experimentally realizing quantum phases of matter and employing control over their properties have become a central goal in condensed matte... more...
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- 2020
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9. Unconventional Landau level transitions in Weyl semimetal NbP
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Minhao Zhao, Zhongbo Yan, Xiaoyi Xie, Yunkun Yang, Pengliang Leng, Mykhaylo Ozerov, Dayu Yan, Youguo Shi, Jinshan Yang, Faxian Xiu, and Shaoming Dong
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Physics and Astronomy (miscellaneous) ,General Materials Science - Published
- 2022
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10. Giant nonlinear anomalous Hall effect induced by spin-dependent band structure evolution
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Xiangyu Cao, Jie-Xiang Yu, Pengliang Leng, Changjiang Yi, Xiaoyang Chen, Yunkun Yang, Shanshan Liu, Lingyao Kong, Zihan Li, Xiang Dong, Youguo Shi, Manuel Bibes, Rui Peng, Jiadong Zang, and Faxian Xiu more...
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- 2022
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11. Ultrafast photothermoelectric effect in Dirac semimetallic Cd3As2 revealed by terahertz emission
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Wei Lu, Zipu Fan, Yunkun Yang, Junchao Ma, Jiawei Lai, Xiaoming Song, Xiao Zhuo, Zhaoran Xu, Jing Liu, Xiaodong Hu, Shuyun Zhou, Faxian Xiu, Jinluo Cheng, and Dong Sun
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Condensed Matter - Materials Science ,Multidisciplinary ,General Physics and Astronomy ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Chemistry ,General Biochemistry, Genetics and Molecular Biology ,Physics - Optics ,Optics (physics.optics) - Abstract
The thermoelectric effects of topological semimetals have attracted tremendous research interest because many topological semimetals are excellent thermoelectric materials and thermoelectricity serves as one of their most important potential applications. In this work, we reveal the transient photothermoelectric response of Dirac semimetallic Cd3As2, namely the photo-Seebeck effect and photo-Nernst effect, by studying the terahertz (THz) emission from the transient photocurrent induced by these effects. Our excitation polarization and power dependence confirm that the observed THz emission is due to photothermoelectric effect instead of other nonlinear optical effect. Furthermore, when a weak magnetic field (~0.4 T) is applied, the response clearly indicates an order of magnitude enhancement on transient photothermoelectric current generation compared to the photo-Seebeck effect. Such enhancement supports an ambipolar transport nature of the photo-Nernst current generation in Cd3As2. These results highlight the enhancement of thermoelectric performance can be achieved in topological Dirac semimetals based on the Nernst effect, and our transient studies pave the way for thermoelectric devices applicable for high field circumstance when nonequilibrium state matters. The large THz emission due to highly efficient photothermoelectric conversion is comparable to conventional semiconductors through optical rectification and photo-Dember effect. more...
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- 2022
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12. A photoactive terahertz modulator based on the Cd3As2 thin film
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Zijie Dai, Yunkun Yang, Weiwei Liu, Manukumara Manjappa, Faxian Xiu, and Ranjan Singh
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Materials science ,Modulation ,Terahertz radiation ,business.industry ,Optoelectronics ,Metamaterial ,Thin film ,business ,Ultrashort pulse ,Plasmon ,Semimetal ,Terahertz spectroscopy and technology - Abstract
We experimentally demonstrated an optical controlled terahertz modulator based on the 3D Dirac semimetal Cd3As2 thin film (~100 nm, λ/3000). Utilizing the time-resolved terahertz spectroscopy, the photoactive characters of Cd3As2 thin film are investigated. The measurements reveal that Cd3As2 modulator exhibits a low optical threshold (< 63.5 μJ/cm2) and ultrafast (< 20 ps) broadband (0.2-1.5 THz) modulation of terahertz waves. Moreover, integrated with the metamaterials structures, Cd3As2 could potentially be used as photo-sensitive and ultrafast reconfigurable terahertz resonant plasmonic/meta-device. more...
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- 2021
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13. Ultrafast photothermoelectric effect in Dirac semimetallic Cd
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Wei, Lu, Zipu, Fan, Yunkun, Yang, Junchao, Ma, Jiawei, Lai, Xiaoming, Song, Xiao, Zhuo, Zhaoran, Xu, Jing, Liu, Xiaodong, Hu, Shuyun, Zhou, Faxian, Xiu, Jinluo, Cheng, and Dong, Sun
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The thermoelectric effects of topological semimetals have attracted tremendous research interest because many topological semimetals are excellent thermoelectric materials and thermoelectricity serves as one of their most important potential applications. In this work, we reveal the transient photothermoelectric response of Dirac semimetallic Cd more...
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- 2021
14. A 3D topological Dirac semimetal/MoO3 thin film heterojunction infrared photodetector with a current reversal phenomenon
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Zehua Hu, Xiaoyi Xie, Yadong Jiang, Jun Gou, Ming Yang, Zhiming Wu, Hongxi Zhou, Ting Yu, Qi Liu, Yunkun Yang, Jiayue Han, Jun Wang, and Faxian Xiu
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Materials science ,Infrared ,Dirac (software) ,Materials Chemistry ,Photodetector ,Quantum efficiency ,Heterojunction ,General Chemistry ,Photoelectric effect ,Thin film ,Topology ,Semimetal - Abstract
Photoelectric detection technology is extremely significant on account of its extensive applications in commercial and military fields, but high-performance array photodetectors based on Dirac semimetal thin film materials are rarely reported. Hence, we demonstrate photodetectors based on a three dimensional (3D) topological Dirac semimetal (DSM) (Cd1−xZnx)3As2/MoO3 array heterojunction, showing ultrahigh photoresponsivity, detectivity and external quantum efficiency in the ultra-broadband spectrum (405–4500 nm) of 3.1 A W−1, 6.4 × 1010 Jones and 855.8%, respectively, meanwhile possessing array unit performance repeatability and excellent time stability under atmospheric conditions at room temperature. The device exhibits an incredible current reversal phenomenon under the action of both light illumination and temperature variation elements, which can be attributed to a thermoelectromotive force effect. These excellent photoelectric properties illustrate that the fabrication of the 3D DSMs/inorganic thin film heterojunction is a suitable method for preparing distinguished infrared array photodetectors in the field of infrared telecommunications and scanning imaging. more...
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- 2020
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15. In situ diamond anvil cell (DAC) experiments on equilibrated carbonate–CO2–H2O interaction under elevated temperature and pressure
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Shan-ming Zhang, Yunkun Yang, Yongsheng Ma, Shan Qin, Xuefeng Zhang, and Bo Liu
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Dolostone ,010506 paleontology ,Atmospheric pressure ,Precipitation (chemistry) ,fungi ,Analytical chemistry ,010502 geochemistry & geophysics ,01 natural sciences ,Diamond anvil cell ,chemistry.chemical_compound ,CO2 content ,chemistry ,Geochemistry and Petrology ,Carbonate ,Solubility ,Dissolution ,Geology ,0105 earth and related environmental sciences - Abstract
The carbonate–CO2–H2O interaction in a closed system under burial conditions was simulated in diamond anvil cell (DAC) with an in situ Raman spectroscopy. Experiments were performed in $${\text{H}}_{2} {\text{CO}}_{3}$$ solution at acidic pH (≈ 5.6), 20–260 °C, and atmospheric pressure to about 400 MPa. Pressure was first solely increased to separately evaluate the pressure effect on carbonate dissolution/precipitation. Then temperature and pressure were increased together alike in the burial process, to monitor the dissolution/precipitation tendency of carbonate during burial. A continuous dissolution was observed for both limestone and dolostone when solely increasing pressure. A rapid dissolution and then continuous precipitation were observed when increasing temperatures and pressures simultaneously. These observations indicate that pressure has a positive effect (prograde solubility), while temperature has a negative effect (retrograde solubility) on CO2 solubility and carbonate dissolution. In case of low initial CO2 content as our experiments revealed, the increase in solid carbonate volume and a counterbalance decrease in porosity caused merely by increasing burial depth are minor ( more...
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- 2019
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16. Broadband Photodetection of Cd3As2: Review and Perspectives
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Yunkun Yang and Faxian Xiu
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- 2022
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17. Impurity-modulated ultrafast carrier dynamics in 3D Dirac semimetal Cd3As2
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Yunkun Yang, Wenjie Zhang, Xian Lin, Guohong Ma, Faxian Xiu, and Peng Suo
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Materials science ,Condensed matter physics ,Physics::Medical Physics ,Dirac (software) ,Physics::Optics ,Cadmium arsenide ,Fluence ,Semimetal ,Optical pumping ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,chemistry ,Impurity ,Topological order ,Condensed Matter::Strongly Correlated Electrons ,Spectroscopy - Abstract
In this work, we use optical pump-terahertz (THz) probe spectroscopy to investigated the impurity-induced topological phase transition and the photo-induced carrier behavior in cadmium arsenide (Cd3As2), a three-dimensional Dirac semimetal. By comparing the dynamics of different temperature and pump fluence, we discuss the carrier dynamics and physical mechanism caused by impurity. more...
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- 2021
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18. Tuning 2D magnetism in Fe3+XGeTe2 films by element doping
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Masaki Kudo, Xiaodong Han, Wenqing Liu, Jiabao Sun, Qiang Li, Xiaoqian Zhang, Lifeng Yin, Ce Huang, Enze Zhang, Shanshan Liu, Zihan Li, Linfeng Ai, Jiayi Zhu, Jin Zou, Yunkun Yang, Jian Shen, Ke Yang, Faxian Xiu, Yanhui Chen, Awadhesh Narayan, Qingsong Deng, Zhiming Liao, Wenzhong Bao, Xiaodong Xu, Takaaki Toriyama, Xiaojiao Guo, Yongbing Xu, Syo Matsumura, and Hua Wu more...
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Multidisciplinary ,Materials science ,Condensed matter physics ,Magnetism ,Doping ,Element (category theory) - Abstract
Two-dimensional (2D) ferromagnetic materials have been discovered with tunable magnetism and orbital-driven nodal-line features. Controlling the 2D magnetism in exfoliated nanoflakes via electric/magnetic fields enables a boosted Curie temperature (TC) or phase transitions. One of the challenges, however, is the realization of high TC 2D magnets that are tunable, robust and suitable for large scale fabrication. Here, we report molecular-beam epitaxy growth of wafer-scale Fe3+XGeTe2 films with TC above room temperature. By controlling the Fe composition in Fe3+XGeTe2, a continuously modulated TC in a broad range of 185–320 K has been achieved. This widely tunable TC is attributed to the doped interlayer Fe that provides a 40% enhancement around the optimal composition X = 2. We further fabricated magnetic tunneling junction device arrays that exhibit clear tunneling signals. Our results show an effective and reliable approach, i.e. element doping, to producing robust and tunable ferromagnetism beyond room temperature in a large-scale 2D Fe3+XGeTe2 fashion. more...
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- 2021
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19. Magnetic-Field-Induced Re-entrance of Superconductivity in Ta
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Enze, Zhang, Xian, Xu, Ce, Huang, Yi-Chao, Zou, Linfeng, Ai, Shanshan, Liu, Pengliang, Leng, Zehao, Jia, Yuda, Zhang, Minhao, Zhao, Zihan, Li, Yunkun, Yang, Jinyu, Liu, Sarah J, Haigh, Zhiqiang, Mao, and Faxian, Xiu more...
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The motion of Abrikosov vortices is the dominant origin of dissipation in type II superconductors subjected to a magnetic field, which leads to a finite electrical resistance. It is generally believed that the increase in the magnetic field results in the aggravation of energy dissipation through the increase in vortex density. Here, we show a distinctive re-entrance of the dissipationless state in quasi-one-dimensional superconducting Ta more...
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- 2020
20. Gate-Tunable Surface States in Topological Insulator β-Ag
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Pengliang, Leng, Fangting, Chen, Xiangyu, Cao, Yuxiang, Wang, Ce, Huang, Xuandong, Sun, Yaozhi, Yang, Junchen, Zhou, Xiaoyi, Xie, Zihan, Li, Enze, Zhang, Linfeng, Ai, Yunkun, Yang, and Faxian, Xiu
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Stimulated by novel properties in topological insulators, experimentally realizing quantum phases of matter and employing control over their properties have become a central goal in condensed matter physics. β-silver telluride (Ag more...
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- 2020
21. A Low Frequency Short Active Monopole Antenna Design and Sensitivity Analysis
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Daihui Mo, Yunkun Yang, Huo-Tao Gao, Huaqiao Zhao, and Haitao Chen
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Physics ,Amplifier ,Acoustics ,020208 electrical & electronic engineering ,Bandwidth (signal processing) ,Astrophysics::Instrumentation and Methods for Astrophysics ,020206 networking & telecommunications ,02 engineering and technology ,Low frequency ,Capacitance ,law.invention ,Capacitor ,law ,0202 electrical engineering, electronic engineering, information engineering ,Active antenna ,Electrical and Electronic Engineering ,Electrical impedance ,Monopole antenna ,Computer Science::Information Theory - Abstract
A conventional passive matching method cannot be used for a low-frequency ultrawideband (UWB) antenna of high performance. In this paper, an amplifier module is combined with a short monopole antenna to design a high-performance active receiving antenna for 10 kHz–100 MHz UWB through model simulation. In addition, theoretical analysis of the antenna’s noise is made, and the theoretical basis for improving the sensitivity of the active antenna is obtained. Finally, the amplifier module is fabricated and the sensitivity of the antenna is tested using the equivalent capacitance substitution method. Tests show that the active antenna has very high sensitivity, bandwidth, and gain, and can be applied to cosmic radio signal detection. more...
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- 2018
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22. A SESAM-like Device Operating beyond 3 Micron
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Yunkun Yang, Shaowei Wang, Yafei Meng, Faxian Xiu, Fengqiu Wang, Xinchao Zhao, Yongbing Xu, and Yi Shi
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Materials science ,Passivation ,business.industry ,Dirac (software) ,Optoelectronics ,Nonlinear optics ,Thin film ,business ,Distributed Bragg reflector ,Absorption (electromagnetic radiation) ,Layer (electronics) ,Semimetal - Abstract
We have for the first time demonstrated a SESAM-like device operating beyond 3 micron. The SESAM-like device is comprised of a highly-reflective Si/SiO Bragg reflector, a Dirac semimetal thin film absorber and a mica substrate as the passivation layer. more...
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- 2020
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23. Third Harmonic Generation (THG) in Three-Dimensional Dirac Semimetal Cd3As2
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Yi Shi, Anran Wang, Yue Sun, Xinran Wang, Yafei Meng, Yunkun Yang, Taotao Li, Faxian Xiu, Danfeng Pan, Xiaoqing Chen, Xiangjing Wang, Kaleem Ullah, and Fengqiu Wang
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Physics ,Graphene ,Dirac (software) ,Nonlinear optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Semimetal ,law.invention ,010309 optics ,Nonlinear system ,Planar ,law ,Simple (abstract algebra) ,Quantum mechanics ,0103 physical sciences ,Third harmonic ,0210 nano-technology - Abstract
We have for the first time reported third harmonic generation in a three-dimensional Dirac semimetal Cd3As2 film. We further demonstrate that a simple planar cavity can be used to significantly enhance the nonlinear response. more...
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- 2020
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24. Slowing down photocarrier relaxation in Dirac semimetal Cd
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Yue, Sun, Yafei, Meng, Ruihong, Dai, Yunkun, Yang, Yongbing, Xu, Shining, Zhu, Yi, Shi, Faxian, Xiu, and Fengqiu, Wang
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In this Letter, we successfully introduce a long-lived non-radiative photocarrier decay component in a Dirac semimetal Cd
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- 2019
25. Weyl Semiconductor Te/Sb 2 Se 3 Heterostructure for Broadband Photodetection and Its Binary Photoresponse by C 60 as Charge‐Regulation Medium
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Silu Peng, Yunkun Yang, Jiayue Han, Hongxi Zhou, Chaoyi Zhang, Jun Wang, Zihan Li, Jun Gou, Xingchao Zhang, Xianchao Liu, and Faxian Xiu
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Semiconductor ,Materials science ,business.industry ,Broadband ,Binary number ,Optoelectronics ,Heterojunction ,Charge (physics) ,Photodetection ,business ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2021
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26. High‐Performance Photodetector based on a 3D Dirac Semimetal Cd 3 As 2 /Tungsten Disulfide (WS 2 ) van der Waals Heterojunction
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Hongxi Zhou, Jun Gou, Chaoyi Zhang, Yunkun Yang, Jun Wang, Jiayue Han, Xianchao Liu, Xingchao Zhang, Rui Pan, and Qi Han
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ultra-low dark current ,Materials science ,Condensed matter physics ,Dirac (software) ,Tungsten disulfide ,3D Dirac semimetal ,Photodetector ,Heterojunction ,QC350-467 ,General Medicine ,Optics. Light ,Semimetal ,TA1501-1820 ,chemistry.chemical_compound ,symbols.namesake ,Cd3As2 ,chemistry ,heterojunction photodetectors ,tungsten disulfide ,symbols ,Applied optics. Photonics ,van der Waals force - Abstract
Recently, heterojunction photodetectors have attracted significant interest due to the multiple degrees of freedom reorganization, integrating advantages of different typed materials. Herein, a high‐performance photodetector based on a 3D Dirac semimetal Cd3As2/tungsten disulfide (WS2) heterojunction is demonstrated, which is constructed by directly transferring exfoliated 2D few layer WS2 on Cd3As2 nano‐belt and following by annealing treatment. The resulting Cd3As2/WS2 heterojunction device presents superior performance with a high on/off ratio (≈5.3 × 104) and a responsivity (Ri) of about 223.5 AW−1 at 520 nm, as well as an outstanding detectivity (D*) of about 2.05 × 1014 Jones at 808 nm near‐IR waveband. However, the optimized noise equivalent power (NEP) is evaluated about 6.17 × 10−14 WHz−1/2 by the noise power density spectrum. The excellent performance can be attributed to a high‐quality heterostructure interface, strong light absorption capacity, and ultralow dark current in a Cd3As2/WS2 heterojunction system. This work provides a promising platform to develop a high‐performance optoelectronic device based on 3D Dirac semimetal and 2D TMDs families. more...
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- 2021
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27. High Mobility 3D Dirac Semimetal (Cd 3 As 2 ) for Ultrafast Photoactive Terahertz Photonics
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Yunkun Yang, Liang Jie Wong, Ranjan Singh, Song Han, Bo Qiang, Faxian Xiu, Thomas CaiWei Tan, Manukumara Manjappa, Zijie Dai, and Weiwei Liu
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Biomaterials ,Materials science ,business.industry ,Terahertz radiation ,Dirac (software) ,Electrochemistry ,Optoelectronics ,Photonics ,Condensed Matter Physics ,business ,Ultrashort pulse ,Semimetal ,Electronic, Optical and Magnetic Materials - Published
- 2021
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28. 3D Dirac semimetal Cd3As2/CuPc heterojunction for promoted visible-infrared photo-detection
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Jiayue Han, Jun Gou, Yunkun Yang, Faxian Xiu, Xianchao Liu, Hongxi Zhou, Jun Wang, Xingchao Zhang, and Rui Pan
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Materials science ,Dirac (software) ,Photodetector ,Cadmium arsenide ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,Inorganic Chemistry ,chemistry.chemical_compound ,Responsivity ,law ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Spectroscopy ,Photocurrent ,business.industry ,Graphene ,Organic Chemistry ,Heterojunction ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,Optoelectronics ,0210 nano-technology ,business ,Dark current - Abstract
Recently, discovery of three-dimensional (3D) topological Dirac/Weyl semi-metal opens up a new frontier fields for neoteric type of photodetectors. As a most representative 3D Dirac semi-metal, Cadmium arsenide (Cd3As2) has ultra-high charge mobility beyond graphene and possess strong light and matter interaction. Herein, photodetector prototype based on micro-nanometer scaled Cd3As2 was developed, which has high photocurrent response even under slight bias of 1 mV and its responsivity could be up to 4.65 A/W at near infrared waveband of 808 nm. Moreover, the Cd3As2/CuPc heterojunction was further introduced for suppress dark current of Dirac semimetal Cd3A2 nanobelt that would effectively improve photoelectric detection performance. As expected, the responsivity (R) of Cd3As2/CuPc has been significantly enhanced in visible (405 nm) to near-infrared (980 nm) region, and maximum R and optimal detectivity (D*) of detector can be reach about 142.5 A/W and 7.83 × 1010 Jones under irradiation of 808 nm laser, respectively. All of the results indicate that 3D Dirac semi-metal Cd3As2 and its heterojunction design are great prospect applied in high-performance broadband detection devices. more...
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- 2021
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29. Third harmonic generation in Dirac semimetal Cd3As2
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Yue Sun, Anran Wang, Xinran Wang, Kaleem Ullah, Yi Shi, Yunkun Yang, Faxian Xiu, Fengqiu Wang, Yafei Meng, and Xiangjing Wang
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010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,Graphene ,business.industry ,Dirac (software) ,Nonlinear optics ,Cadmium arsenide ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Semimetal ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,0103 physical sciences ,Femtosecond ,Optoelectronics ,Thin film ,0210 nano-technology ,business - Abstract
Cadmium arsenide (Cd3As2), an emerging three-dimensional Dirac semimetal, has recently generated significant interest in the area of ultrafast optics and optoelectronics. However, its nonlinear susceptibility has not been experimentally studied; thus, it is not yet possible to evaluate its potential in nonlinear optics. In this work, we investigate third harmonic generation (THG) in a 100 nm thick Cd3As2 film using broadband infrared femtosecond lasers (across 1500–2350 nm). The χ3 of Cd3As2 (2.30 × 10−19 m2 V−2) is obtained by comparing the THG spectra with a glass substrate, graphene, and monolayer MoS2. We further demonstrate a simple approach to enhance the THG signal by introducing an underlying planar micro-cavity. An enhancement of about 420 times in the THG signal was recorded at ≃1560 nm. Our results indicate that Cd3As2 thin films can provide a similar platform for nonlinear optics with respect to graphene and may offer unique potential in the mid-infrared due to its broadband light–matter interaction and excellent tunability. more...
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- 2020
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30. Outbreak of NDM-1-producing Klebsiella pneumoniae ST76 and ST37 isolates in neonates
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Weiping Liu, Baixing Ding, Fan Yang, Hong Zhang, L. Sun, Fupin Hu, Xin Xu, Yunkun Yang, Jun Zhu, and Du-ming Zhu
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Male ,0301 basic medicine ,Microbiology (medical) ,China ,Imipenem ,medicine.medical_specialty ,Gene Transfer, Horizontal ,Genotype ,Klebsiella pneumoniae ,030106 microbiology ,Microbial Sensitivity Tests ,Tigecycline ,Biology ,Polymerase Chain Reaction ,Meropenem ,beta-Lactam Resistance ,beta-Lactamases ,Disease Outbreaks ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,medicine ,Pulsed-field gel electrophoresis ,Humans ,Child ,Retrospective Studies ,Cross Infection ,Infant, Newborn ,Infant ,Sequence Analysis, DNA ,General Medicine ,Hospitals, Pediatric ,bacterial infections and mycoses ,biology.organism_classification ,Klebsiella Infections ,Surgery ,Molecular Typing ,Infectious Diseases ,chemistry ,Conjugation, Genetic ,Colistin ,Multilocus sequence typing ,Female ,Ertapenem ,Plasmids ,medicine.drug - Abstract
The purpose of this study was to investigate the epidemiological characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) in Shanghai Children’s Hospital in China. Twenty-two non-duplicate CRKP strains were collected from pediatric patients between March and June in 2014. Antimicrobial susceptibility testing was conducted by the agar dilution method. Beta-lactamases were characterized by polymerase chain reaction (PCR) and DNA sequencing. The transferability of bla NDM-1 was investigated by conjugation experiment. The plasmids bearing antibiotic resistance genes were characterized by S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern hybridization. Clonal relatedness was evaluated by PFGE and multilocus sequence typing (MLST). The clinical data of patients were retrospectively reviewed. The 22 CRKP strains were resistant to most of the antimicrobial agents tested, except tigecycline and colistin. Overall, 59, 77, and 100 % of these strains were resistant to imipenem, meropenem, and ertapenem, respectively. The bla NDM-1 was positive in 77.3 % (17/22) of the CRKP strains, of which the 16 isolates from inpatients were designated as ST37 (n = 9) and ST76 (n =7) and one isolate from an outpatient belonged to ST846. The 17 bla NDM-1-positive isolates belonged to PFGE type A (n = 9), type C (n = 7), or type B (n = 1). The plasmids bearing bla NDM-1 could be transferred into recipient Escherichia coli J53 through conjugation in 88.2 % (15/17) of the strains. The hybridization results showed that the plasmids carrying the bla NDM-1 gene were approximately 50–240 kb in size. This is the first report of an outbreak caused by NDM-1-producing K. pneumoniae ST76 and ST37 among neonates. more...
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- 2016
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31. Slowing down photocarrier relaxation in Dirac semimetal Cd3As2 via Mn doping
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Yafei Meng, Yongbing Xu, Shining Zhu, Yue Sun, Yunkun Yang, Ruihong Dai, Fengqiu Wang, Faxian Xiu, and Yi Shi
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Materials science ,Condensed matter physics ,business.industry ,Doping ,Dirac (software) ,Relaxation (NMR) ,Saturable absorption ,Atomic and Molecular Physics, and Optics ,Semimetal ,Wavelength ,Optics ,Condensed Matter::Strongly Correlated Electrons ,Photonics ,Thin film ,business - Abstract
In this Letter, we successfully introduce a long-lived non-radiative photocarrier decay component in a Dirac semimetal Cd3As2 thin film via Mn doping. The long-lived decay component is found to vary between 200 ps and 2.8 ns with different Mn concentrations and probing wavelengths. Most remarkably, the elongated transients persist over the important mid-infrared wavelengths (observed up to 4 μm). Saturable absorption measurement reveals stronger modulation effects for long-width pulses (∼80 ps) from the Mn-doped samples. Our results provide new insights into the effect of transition-metal doping on the ultrafast optical properties of Dirac semimetal Cd3As2 and establish Cd3As2 as a highly amendable material for mid-infrared photonic applications. more...
- Published
- 2019
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32. Ultrafast photocarrier dynamics in a 3D Dirac semimetal Cd3As2 film studied with terahertz spectroscopy
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Zuanming Jin, Weimin Liu, Jiajia Guo, Xian Lin, Qi Lu, Yunkun Yang, Wenjie Zhang, Gang Chen, Wanying Zhao, Faxian Xiu, Chao Zhang, Guohong Ma, Lin Wang, and Peng Suo
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010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,Scattering ,Terahertz radiation ,Photoconductivity ,Relaxation (NMR) ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Semimetal ,Terahertz spectroscopy and technology ,Optical pumping ,Photoexcitation ,Condensed Matter::Materials Science ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,Atomic physics ,0210 nano-technology - Abstract
By employing optical pump Terahertz (THz) probe spectroscopy, a three dimensional (3D) Dirac semimetal, Cd3As2 film, was investigated systematically at room temperature. After photoexcitation at 400/800 nm, the rise time of photoenhanced THz photoconductivity (PC) is about ∼1.0 ps, increasing slightly with the pump fluence, in which time scale, photoexcited electrons and holes establish separate Fermi distribution with electrons in the conduction band and holes in the valence band via fast carrier-carrier scattering and carrier-phonon coupling. The subsequent THz PC relaxation shows single exponential decay with a time constant of ∼6.0 ps that is independent of pump fluence. The relaxation process is dominated by the electron-hole recombination via a radiative and nonradiative way, which is mediated by the phonon-phonon scattering. The optically induced THz complex PC can be well fitted with the Drude-Smith model. Our experimental results shed light on understanding the photocarrier dynamics of the 3D Dirac semimetal materials at THz frequency. more...
- Published
- 2019
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33. Dirac semimetal saturable absorber with actively tunable modulation depth
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Yafei Meng, Shuchao Qin, Yue Sun, Hongzhu Jiang, Yi Shi, Shining Zhu, Faxian Xiu, Yunkun Yang, and Fengqiu Wang
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Materials science ,business.industry ,Saturable absorption ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Semimetal ,law.invention ,010309 optics ,Amplitude modulation ,Optics ,law ,0103 physical sciences ,Femtosecond ,Optoelectronics ,Irradiation ,0210 nano-technology ,business - Abstract
In this Letter, we demonstrate an electrically contacted saturable absorber (SA) device based on topological Dirac semimetal Cd3As2. With a current-induced temperature change in the range of 297–336 K, the modulation depth of the device is found to be significantly altered from 33% to 76% (under the irradiation of a 1560 nm femtosecond laser). The broad tuning of the modulation depth is attributed to the strong temperature dependence of the carrier concentration close to room temperature. The simple tuning mechanism uncovered here, together with the compatibility with III-V compounds substrate, such as GaAs, points to the potential of fabricating broadband, electrically tunable, SESAM-like devices based on emerging bulk Dirac materials. more...
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- 2019
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34. Theory of Inhomogeneous Polymers Lattice Model for the Interface between Flexible Polymer and Small Molecular Liquid Crystal
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Yuhong Chen, Huiwei Zhang, Jixi Li, and Yunkun Yang
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chemistry.chemical_classification ,Quantitative Biology::Biomolecules ,Phase transition ,Materials science ,Polymer ,Condensed Matter Physics ,Thermotropic crystal ,Condensed Matter::Soft Condensed Matter ,Surface tension ,Crystallography ,chemistry ,Chemical physics ,Liquid crystal ,Phase (matter) ,Anisotropy ,Lattice model (physics) - Abstract
The Helfand's lattice theory of polymer interface has been extended to deal with the interface between thermotropic small molecular liquid crystals and flexible polymers. The main findings of the theoretical calculations are: (1) the interface of flexible polymer and the ordered nematic liquid crystal is very narrow due to the fact that the ordered nematic phase excludes strongly the flexible polymer segments; (2) the interfacial tension and the anisotropic factors of polymer bonds posses a first order transition, when the liquid crystal-rich phase undergoes the isotropic to nematic phase transition, which is characterized mainly by the fact that polymer bonds prefer to return back to the saturated polymer solution phase by reducing the probability of stretching into the liquid crystalline phase. more...
- Published
- 1995
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35. The anisotropic linear and quadratic magneto-optical Kerr effects in epitaxial Fe/GaAs(110) film
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Yue-Rui Chen, J. H. Liang, Liaoxin Sun, Yizheng Wu, C. Zhou, and Yunkun Yang
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010302 applied physics ,Coupling ,Materials science ,Kerr effect ,Physics and Astronomy (miscellaneous) ,Field (physics) ,Condensed matter physics ,Transfer-matrix method (optics) ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,General Relativity and Quantum Cosmology ,Quadratic equation ,Magneto-optic Kerr effect ,0103 physical sciences ,0210 nano-technology ,Anisotropy ,Nonlinear Sciences::Pattern Formation and Solitons - Abstract
We investigated the magneto-optical Kerr effects in C2v symmetric Fe/GaAs(110) film and quantitatively separated the linear and quadratic Kerr contributions with the rotating field method. The linear Kerr effect was experimentally found to have twofold anisotropy with crystal orientation, in well agreement with the theoretical prediction. In addition, the quadratic Kerr effects exhibit both twofold and fourfold anisotropy. The calculation based on a 4 × 4 transfer matrix method indicates that the anisotropies of the linear and quadratic Kerr effects both originate from the second order magneto-optical coupling. The C2v symmetric film with anisotropic linear Kerr effect may have a potential application on the future precise magneto-optical sensors. more...
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- 2016
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36. PPE protein (Rv3425) from DNA segment RD11 of Mycobacterium tuberculosis: a potential B-cell antigen used for serological diagnosis to distinguish vaccinated controls from tuberculosis patients
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Jianqiang Lei, Min Zhang, Yunkun Yang, Yundai Chen, Jiuling Wang, Honghai Wang, and Huiwei Zhang
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Microbiology (medical) ,Adult ,Male ,Tuberculosis ,diagnosis ,Enzyme-Linked Immunosorbent Assay ,Biology ,complex mixtures ,Serology ,law.invention ,Microbiology ,Mycobacterium tuberculosis ,Open Reading Frames ,Antigen ,Tuberculosis diagnosis ,Bacterial Proteins ,law ,medicine ,Humans ,Serologic Tests ,RNA, Messenger ,Aged ,Antigens, Bacterial ,B-Lymphocytes ,PPE family protein ,Rv3425 protein ,Vaccination ,General Medicine ,Middle Aged ,medicine.disease ,biology.organism_classification ,Virology ,Peptide Fragments ,Recombinant Proteins ,Open reading frame ,Infectious Diseases ,region of difference ,Recombinant DNA ,BCG Vaccine ,Female - Abstract
Proteins encoded by a 9.5-kb DNA segment, termed the region of difference (RD), of Mycobacterium tuberculosis have been demonstrated to be important in bacterial virulence, vaccine development and the design of diagnostic reagents. This study evaluated the immunogenic properties of Rv3425, a member of the PPE family of proteins, encoded by an open reading frame found in RD11 of M. tuberculosis, in comparison with two other well-known antigens, the early secreted antigen target 6 (ESAT-6) and the 10-kDa culture filtrate protein (CFP-10). RT-PCR demonstrated that Rv3425 mRNA is expressed in liquid culture by M. tuberculosis H37Rv. When tested in a conventional ELISA in the form of a His-tagged recombinant protein, Rv3425 revealed a statistically significant antigenic distinction between healthy bacille Calmette–Guérin (BCG)-vaccinated controls and tuberculosis (TB) patients (p more...
- Published
- 2007
37. High frequency electromagnetic properties of interstitial-atom-modified Ce2Fe17NX and its composites
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Jiang Wei, J. B. Yang, Weiyou Yang, L. Z. Li, Y. H. Xia, Yunkun Yang, Honglin Du, Chao Yun, Y. B. Yang, Cheng Wang, Jingzhi Han, S. Q. Liu, and Rui Wu
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Magnetization ,Magnetic anisotropy ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Permeability (electromagnetism) ,Composite number ,Reflection loss ,Intermetallic ,Composite material ,Anisotropy ,Microwave - Abstract
The magnetic and microwave absorption properties of the interstitial atom modified intermetallic compound Ce2Fe17NX have been investigated. The Ce2Fe17NX compound shows a planar anisotropy with saturation magnetization of 1088 kA/m at room temperature. The Ce2Fe17NX paraffin composite with a mass ratio of 1:1 exhibits a permeability of μ′ = 2.7 at low frequency, together with a reflection loss of −26 dB at 6.9 GHz with a thickness of 1.5 mm and −60 dB at 2.2 GHz with a thickness of 4.0 mm. It was found that this composite increases the Snoek limit and exhibits both high working frequency and permeability due to its high saturation magnetization and high ratio of the c-axis anisotropy field to the basal plane anisotropy field. Hence, it is possible that this composite can be used as a high-performance thin layer microwave absorber. more...
- Published
- 2014
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38. The asymmetric magnetization reversal in exchange biased granular Co/CoO films
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Xiaolei Peng, Y. H. Xia, Yun Zhang, S. Q. Liu, Rui Wu, Yunkun Yang, J. B. Fu, Jiang Wei, Cheng Wang, and J. B. Yang
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Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,media_common.quotation_subject ,Magnetization reversal ,chemistry.chemical_element ,Magnetic hysteresis ,Asymmetry ,Grain size ,Condensed Matter::Materials Science ,Magnetic anisotropy ,chemistry ,Antiferromagnetism ,Anisotropy ,Cobalt ,media_common - Abstract
A special kind of asymmetric magnetization reversal characterized by a sharp step in the second quadrant of the hysteresis loop has been investigated in the exchange biased Co/CoO films. This asymmetry only exists in the film where the small clusters grow to form islands. A bimodal distribution of the first-order reversal curves diagram demonstrates that the irreversible magnetization reversal is composed of the free part and exchange biased part, originating from the grains smaller and larger than 6 nm in the film, respectively. The finite-size effect of the antiferromagnetic anisotropy in the ultrafine grains is responsible for this asymmetry. more...
- Published
- 2014
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39. Magnetic manipulation by resistance switching in CeO2/PrBa2Cu3O7−δ/Pt heterostructure: The role of oxygen vacancies
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G. J. Lian, J. B. Fu, Xuegang Chen, Y. X. Zhang, S. Q. Liu, J. B. Yang, Yu Wang, Guangcheng Xiong, J. R. Sun, Yun Zhang, Yunkun Yang, and Chao Yun
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High-temperature superconductivity ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Exchange interaction ,chemistry.chemical_element ,Heterojunction ,Electronic structure ,Variable-range hopping ,Oxygen ,law.invention ,Condensed Matter::Materials Science ,Ferromagnetism ,chemistry ,law ,Electric field - Abstract
Pronounced bipolar resistance switching with a good retention property has been observed in CeO2/PrBa2Cu3O7−δ/Pt heterostructure. The low resistance state and high resistance state exhibited distinguished ferromagnetic signals, as compared to the nearly non-magnetic initial state. It is found that the migration of the oxygen vacancies under electric field is mainly responsible for the electric and the magnetic changes. The modified interfacial electronic structure by the oxygen vacancy migration and the trapping/detrapping of the carriers leads to the resistance switching. The exchange interaction of the hydrogen-like orbitals formed around the singly occupied oxygen vacancies in CeO2 is accounting for the emerged and modulated ferromagnetic signals. Temperature dependence of resistance in the low resistance state follows a variable range hopping law, further confirming that the amount of oxygen vacancies in the CeO2 layer directly affects the hydrogen-like orbital radius, which determines the strength of... more...
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- 2013
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40. Monte Carlo simulation of magnetoelectric coupling in multiferroic BiFeO3
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Lain-Jong Li, Jiangyu Li, and Yunkun Yang
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Physics ,Condensed Matter::Materials Science ,Dipole ,Hysteresis ,Ferroelasticity ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Spins ,Monte Carlo method ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,Multiferroics ,Ferroelectricity - Abstract
A Monte Carlo method is developed to simulate the magnetoelectric coupling in multiferroic BiFeO3 with coexistence of ferroelastic, ferroelectric, and antiferromagnetic order parameters. Long-range interactions among dipoles and spins are summed through cutoff, while elastic interactions among transformation strain are evaluated using Green’s function method. Short-range interactions among ferroelectric dipoles and antiferromagnetic spins are also considered. Through the Monte Carlo simulation, coupled ferroelastic, ferroelectric, and antiferromagnetic domains are demonstrated, the switching of magnetic spins by electric field is verified, and mechanical switching of spins is also predicted. more...
- Published
- 2011
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41. Epitaxial growth and structural analysis of AlN∕GaN heterostructures
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Yousheng Zou, Z. Q. Yao, Zunzhong Ye, Yunkun Yang, Shuit-Tong Lee, Yaxun Zhang, and Wenjun Zhang
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Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Sputtering ,Sapphire ,Optoelectronics ,Crystal growth ,Thin film ,Sputter deposition ,business ,Epitaxy ,Single crystal ,Crystallographic defect - Abstract
Single crystal AlN thin films were epitaxially grown on GaN/sapphire (0001) substrates on a macroscopic scale by magnetron sputtering. The microscopic structure and orientation degree of the AlN epilayers were studied by high-resolution transmission electron microscopy, high-resolution x-ray diffraction, and reciprocal spacing mapping. It was revealed that the AlN epilayers have high in-plane and out-of-plane orientation degrees and low defect density. The electrical and optical properties of the AlN epilayers were also studied, and the results suggest that the AlN epilayers grown by sputtering may be employed in the fabrication of GaN-based light-emitting diode devices with increased efficiency. more...
- Published
- 2007
- Full Text
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