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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 154-160页

作者： Yin-Zou Zhao Jiao-Jiao Song Qi-Yi Wu Hao Liu Chen Zhang Bo Chen Hong-Yi Zhang Zhen-Hua Chen Yao-Bo Huang Xue-Qing Ye Ya-Hua yuan yu-xia duan Jun He Jian-Qiao Meng School of Physics Central South UniversityChangsha 410083China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China

Synchrotron-based angle-resolved photoemission spectroscopy was employed to investigate the temperature evolution of the Yb 4 f spectral for surface and bulk in the Kondo lattice YbCu_(2)Si_(2).Our study quantitatively distinguishes between the surface and bulk hybridization processes,revealing that the onset temperatures for both surface and bulk hybridization processes are significantly higher than the Kondo ***,we found that the effective surface Kondo temperature is much lower than that of the *** findings offer valuable insights into the understanding of heavy fermion physics.

关键词： Kondo lattice angle-resolved photoemission spectroscopy electronic structure hybridization surface state

Ultrafast optical spectroscopy evidence of pseudogap and electronphonon coupling in an iron-based superconductor KCa_(2)Fe_(4)As_(4)F_(2)

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Science China(Physics,Mechanics & Astronomy) 2022年第3期65卷 92-98页

作者： Chen Zhang Qi-Yi Wu Wen-Shan Hong Hao Liu Shuang-Xing Zhu Jiao-Jiao Song Yin-Zou Zhao Fan-Ying Wu Zi-Teng Liu Shu-yu Liu Ya-Hua yuan Han Huang Jun He Shiliang Li Hai-yun Liu yu-xia duan Hui-Qian Luo Jian-Qiao Meng School of Physics and Electronics Central South UniversityChangsha 410083China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China Beijing Academy of Quantum Information Sciences Beijing 100193China

We use ultrafast optical spectroscopy to study the nonequilibrium quasiparticle relaxation dynamics of the iron-based superconductor KCa_(2)Fe_(4)A_(s4)F_(2)with T_(c)= 33.5 K. Our results reveal a possible pseudogap(△_(PG)=(2.4 ± 0.1) me V) below T*≈ 50 K but prior to the opening of a superconducting gap(△SC(0) ≈(4.3 ± 0.1) me V). Measurements under high pump fluence reveal two distinct, coherent phonon oscillations with 1.95 and 5.51 THz frequencies, respectively. The high-frequency A1 g(2) mode corresponds to the c-axis polarized vibrations of Fe As planes with a nominal electron-phonon coupling constant λA1 g(2)= 0.194 ± *** findings suggest that the pseudogap is likely a precursor of superconductivity, and the electron-phonon coupling may play an essential role in the superconducting pairing in KCa_(2)Fe_(4)A_(s4)F_(2).

关键词： KCa_(2)Fe_(4)A_(s4)F_(2) ultrafast spectroscopy electron-phonon coupling superconductivity

Itinerant to relocalized transition of felectrons in the Kondo insulator CeRu_(4)Sn_(6)

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Frontiers of physics 2023年第5期18卷 153-160页

作者： Fan-Ying Wu Qi-Yi Wu Chen Zhang Yang Luo xiangqi Liu yuan-Feng Xu Dong-Hui Lu Makoto Hashimoto Hao Liu Yin-Zou Zhao Jiao-Jiao Song Ya-Hua yuan Hai-yun Liu Jun He yu-xia duan Yan-Feng Guo Jian-Qiao Meng School of Physics and Electronics Central South UniversityChangsha 410083China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Center for Correlated Matter and School of Physics Zhejiang UniversityHangzhou 310058China Stanford Synchrotron Radiation Lightsource SLAC National Accelerator LaboratoryMenlo ParkCA 94025USA Beijing Academy of Quantum Information Sciences Beijing 100085China ShanghaiTech Laboratory for Topological Physics ShanghaiTech UniversityShanghai 201210China

The three-dimensional electronic structure and the nature of Ce 4f electrons of the Kondo insulator CeRu_(4)Sn_(6)are investigated by angle-resolved photoemission spectroscopy,utilizing tunable photon *** results reveal(i)the three-dimensional k-space nature of the Fermi surface,(ii)the localized-to-itinerant transition of f electrons occurs at a much high temperature than the hybridization gap opening temperature,and(iii)the“relocalization”of itinerant f-electrons below 25 K,which could be the precursor to the establishment of magnetic order.

关键词： Kondo insulator heavy fermion ARPES electronic structure relocalization

Charge density wave order and electron-boson coupling in ternary superconductor Bi_(2)Rh_(3)Se_(2)

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Science China(Physics,Mechanics & Astronomy) 2023年第7期66卷 120-126页

作者： Zi-Teng Liu Chen Zhang Qi-Yi Wu Hao Liu Bo Chen Zhi-Bo Yin Sheng-Tao Cui Zhe Sun Shuang-Xing Zhu Jiao-Jiao Song Yin-Zou Zhao Hong-Yi Zhang Xue-Qing Ye Fan-Ying Wu Shu-yu Liu xiao-Fang Tang Ya-Hua yuan yun-Peng Wang Jun He Hai-yun Liu yu-xia duan Jian-Qiao Meng School of Physics and Electronics Central South UniversityChangsha 410083China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Department of Physics and Electronic Science Hunan University of Science and TechnologyXiangtan 411201China Beijing Academy of Quantum Information Sciences Beijing 100085China

The newly discovered ternary chalcogenide superconductor Bi_(2)Rh_(3)Se_(2) has attracted growing attention,which provides an opportunity to explore the interplay between charge density wave(CDW)order and ***,whether the phase transition around 240 K can be attributed to the formation of CDW remains *** help resolve the debate,we study the electronic structure of Bi_(2)Rh_(3)Se_(2) by angle-resolved photoemission spectroscopy,focusing on the nature of its high-temperature phase transition around 240 *** measurements demonstrate that the phase transition at 240 K is a second-order CDW phase *** results reveal(i)a 2×2 CDW order in Bi_(2)Rh_(3)Se_(2),accompanied by the reconstruction of electronic structure,such as band folding,band splitting,and opening of CDW gaps at and away from the Fermi level;(ii)the existence of electron-boson coupling,which is manifested as an apparent kink and peak-dip-hump structure in *** observations thus enable us to shed light on the nature of CDW order and superconductivity in Bi_(2)Rh_(3)Se_(2).

关键词： charge density wave electron-boson coupling angle-resolved photoemission spectroscopy electronic structure Chalcogenide

Time-Resolved Study of Pseudogap and Superconducting Quasiparticle Dynamics in Ca0.82La0.18Fe1-xNixAs2

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Chinese Physics Letters 2020年第6期37卷 86-89页

作者： Cong-Ying Jiang Hai-Ying Song T.Xie C.Liu H.Q.Luo S.Z.Zhao Xiu Zhang X.C.Nie Jian-Qiao Meng yu-xia duan H.Y.Liu Shi-Bing Liu Strong-Field and Ultrafast Photonics Lab Beijing Engineering Research Center of Laser TechnologyInstitute of Laser EngineeringBeijing University of TechnologyBeijing 100124China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China School of Physics and Electronics Central South UniversityChangsha 410083China Beijing Academy of Quantum Information Sciences Beijing 100193China

We use femtosecond time-resolved optical reflectivity to study the photoexcited quasiparticle(QP)dynamics in the iron-based 112 type superconducting(SC)samples Ca0.82La0.18Fe1-xNixAs2,with x=0 and *** the parent sample,a fast and a slow relaxation emerge at temperatures below the magnetic-structure(MS)transition Tms≈50 K and the SC transition Tc≈33 K,*** latter obviously corresponds to an SC QP dynamics,which is further confirmed in the x=0.024 sample with Tc≈25 *** former suggests that a partial of photoexcited QP relaxation through a pesudogap(PG)channel,which is absent in the doped x=0.024 sample without the MS transition.

关键词： transition. relaxation excited

The 4f-Hybridization Strength in Ce_(m)M_(n)In_(3m+2n) Heavy-Fermion Compounds Studied by Angle-Resolved Photoemission Spectroscopy

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Chinese Physics Letters 2021年第10期38卷 37-42页

作者： Jiao-Jiao Song Yang Luo Chen Zhang Qi-Yi Wu Tomasz Durakiewicz Yasmine Sassa Oscar Tjernberg Martin Mansson Magnus HBerntsen Yin-Zou Zhao Hao Liu Shuang-Xing Zhu Zi-Teng Liu Fan-Ying Wu Shu-yu Liu Eric DBauer Ján Rusz Peter MOppeneer Ya-Hua yuan yu-xia duan Jian-Qiao Meng School of Physics and Electronics Central South UniversityChangsha 410083China Institute of Physics Maria Curie Sklodowska University20-031 LublinPoland Department of Physics and Astronomy Uppsala UniversityBox 516S-75120 UppsalaSweden Department of Physics Chalmers University of Technology41296 GoteborgSweden Department of Applied Physics KTH Royal Institute of TechnologyAlba Nova10691 StockholmSweden Condensed Matter and Magnet Science Group Los Alamos National LaboratoryLos AlamosNew Mexico 87545USA

We systemically investigate the nature of Ce 4f electrons in structurally layered heavy-fermion compounds Ce_(m)M_(n)In_(3m+2n)(with M=Co,Rh,Ir,and Pt,m=1,2,n=0–2),at low temperature using on-resonance angle-resolved photoemission *** heavy quasiparticle bands f^(0),f^(1/7/2)and f^(1/5/2),are observed in all compounds,whereas their intensities and energy locations vary greatly with *** strong f0 states imply that the localized electron behavior dominates the Ce 4f *** Ce 4f electrons are partially hybridized with the conduction electrons,making them have the dual nature of localization and *** quantitative comparison reveals that the f^(1/5/2)–f^(0)intensity ratio is more suitable to reflect the 4f-state hybridization strength.

关键词： spectroscopy materials strength

Actively tunable electromagnetically induced transparency in hybrid Dirac-VO2 metamaterials

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Optoelectronics Letters 2025年第1期21卷 13-20页

作者： DI Ke XIE Meng xia Huarong CHENG Anyu LIU yu DU Jiajia Department of Optoelectronic Engineering Chongqing University of Post and Telecommunications Chongqing Key Laboratory of Autonomous Navigation and Microsystem Chongqing University of Posts and Telecommunications Department of Automation Chongqing University of Post and Telecommunications

In this paper, we present a metamaterial structure of Dirac and vanadium dioxide（VO2） and investigate its optical properties using the finite-difference time-domain（FDTD） technique. Using the phase transition feature of VO2, the design can realize active tuning of the plasmon induced transparency（PIT） effect at terahertz frequency, thereby converting from a single PIT to a double-PIT. When VO2is in the insulating state, the structure is symmetric to obtain a single-band PIT effect. When VO2is in the metallic state, the structure turns asymmetric to realize a dual-band PIT effect. This design provides a reference direction for the design of actively tunable metamaterials. Additionally, it is discovered that the transparent window's resonant frequency and the Fermi level in this structure have a somewhat linear relationship. In addition, the structure achieves superior refractive index sensitivity in the terahertz band, surpassing 1 THz/RIU. Consequently, the design exhibits encouraging potential for application in refractive index sensors and optical switches.

关键词： Transparency

Growth, characterization, and Raman spectra of the 1T phases of TiTe_(2), TiSe_(2), and TiS_(2)

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Chinese Physics B 2022年第3期31卷 482-487页

作者： xiao-Fang Tang Shuang-Xing Zhu Hao Liu Chen Zhang Qi-Yi Wu Zi-Teng Liu Jiao-Jiao Song xiao Guo Yong-Song Wang He Ma Yin-Zou Zhao Fan-Ying Wu Shu-yu Liu Kai-Hui Liu Ya-Hua yuan Han Huang Jun He Wen Xu Hai-yun Liu yu-xia duan Jian-Qiao Meng Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031China University of Science and Technology of China Hefei 230026China School of Physics and Electronics Central South University Changsha 410083China State Key Laboratory for Mesoscopic Physics Collaborative Innovation Center of Quantum Matter School of Physics Peking UniversityBeijing 100871China Beijing Academy of Quantum Information Sciences Beijig 10085China

High-quality large 1T phase of TiX_(2)(X = Te, Se, and S) single crystals have been grown by chemical vapor transport using iodine as a transport agent. The samples are characterized by compositional and structural analyses, and their properties are investigated by Raman spectroscopy. Several phonon modes have been observed, including the widely reported A_(1g) and E_(8) modes, the rarely reported E_(u) mode(-83 cm^(-1) for TiTe_(2), and -185 cm^(-1)for TiS_(2)), and even the unexpected K mode(-85 cm^(-1)) of TiTe_(2). Most phonons harden with the decrease of temperature, except that the K mode of TiTe_(2) and the E_(u) and “A_(2u)/Sh” modes of TiS_(2) soften with the decrease of temperature. In addition, we also found phonon changes in TiSe_(2) that may be related to charge density wave phase transition. Our results on TiX_(2) phonons will help to understand their charge density wave and superconductivity.

关键词： transition-metal dichalcogenides chemical vapor transport Raman phonon

Cross-subcarrier precoder design for massive MIMO-OFDM downlink with symplectic optimization

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Science China(Information Sciences) 2025年

作者： yu-Xuan ZHANG An-An LU xiang-Gen xia Xi-Qi GAO National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories Department of Electrical and Computer Engineering University of Delaware

We propose a cross-subcarrier precoder design(CSPD) for massive multiple-input multiple-output(MIMO) orthogonal frequency division multiplexing(OFDM) downlink. This work aims to significantly improve the channel estimation and signal detection performance by enhancing the smoothness of the frequency domain effective channel. This is accomplished by designing a few vectors known as the transform domain precoding vectors(TDPVs), which are then transformed into the frequency domain to generate the precoders for a set of subcarriers. To combat the effect of channel aging, the TDPVs are optimized under imperfect channel state information(CSI). The optimal precoder structure is derived by maximizing an upper bound of the ergodic weighted sum-rate(WSR) and utilizing the a posteriori beam-based statistical channel model(BSCM). To avoid the large-dimensional matrix inversion, we propose an algorithm with symplectic optimization. Simulation results indicate that the proposed cross-subcarrier precoder design significantly outperforms conventional methods.

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Perilipin-2 mediates ferroptosis in oligodendrocyte progenitor cells and myelin injury after ischemic stroke

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Neural Regeneration Research 2025年第7期20卷 2015-2028页

作者： Jian Yang Jiang Wu Xueshun Xie Pengfei xia Jinxin Lu Jiale Liu Lei Bai xiang Li Zhengquan yu Haiying Li Department of Neurosurgery&Brain and Nerve Research Laboratory The First Affiliated Hospital of Soochow UniversitySuzhouJiangsu ProvinceChina Institute of Stroke Research Soochow UniversitySuzhouJiangsu ProvinceChina

Differentiation of oligodendrocyte progenitor cells into mature myelin-forming oligodendrocytes contributes to *** of remyelination due to oligodendrocyte progenitor cell death can result in severe nerve *** is an iron-dependent form of regulated cell death caused by membrane rupture induced by lipid peroxidation,and plays an important role in the pathological process of ischemic ***,there are few studies on oligodendrocyte progenitor cell *** analyzed transcriptome sequencing data from GEO databases and identified a role of ferroptosis in oligodendrocyte progenitor cell death and myelin injury after cerebral *** analysis suggested that perilipin-2(PLIN2)was involved in oligodendrocyte progenitor cell ***2 is a lipid storage protein and a marker of hypoxia-sensitive lipid droplet *** further investigation,we established a mouse model of cerebral ischemia/*** found significant myelin damage after cerebral ischemia,as well as oligodendrocyte progenitor cell death and increased lipid peroxidation levels around the infarct *** ferroptosis inhibitor,ferrostatin-1,rescued oligodendrocyte progenitor cell death and subsequent myelin *** also found increased PLIN2 levels in the peri-infarct area that co-localized with oligodendrocyte progenitor ***2 knockdown rescued demyelination and improved neurological *** findings suggest that targeting PLIN2 to regulate oligodendrocyte progenitor cell ferroptosis may be a potential therapeutic strategy for rescuing myelin damage after cerebral ischemia.

关键词： bioinformatics bulk RNA sequencing ferroptosis ischemic stroke myelin injury oligodendrocyte progenitor cell perilipin-2 single-cell RNA sequencing