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Interfacial DMI in Fe/Pt thin films grown on different buffer layers

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Chinese physics B 2024年第4期33卷 712-718页

作者：张文君魏菲刘冰周阳康仕寿孙兵 School of physics and Electronic Information Weifang UniversityWeifang 261061China School of physics and State Key laboratory of Crystal Materials Shandong UniversityJinan 250100China

We study the interfacial Dzyaloshinskii-Moriya interactions(i-DMI)of Fe/Pt bilayers grown on Si substrates with MgO,SiO_(2),or Ta each as a buffer layer on the basis of wave-vector-resolved Brillouin light scattering(BLS)*** obtained i-DMI energy values for Fe/Pt on MgO,Ta,and SiO_(2) buffer layers are 0.359,0.321,and 0.274 mJ/m~2,*** large i-DMI value observed in Fe/Pt system on the MgO buffer layer can be attributed to the good interfacial quality and the Rshaba effect at the MgO/Fe ***,the MgO/Fe/Pt system,benefiting from better sample quality,exhibits a lower damping ***,layer-resolved first-principles calculations are carried out to gain a more in-depth understanding of the origin of the i-DMI in the Fe/Pt *** results indicate that in the Fe(110)/Pt(111)system,the substantial DMI energy between Fe spins at the interface is related to a significant change in spin-orbit coupling(SOC)energy in the neighboring Pt *** contrast,for the MgO(002)/Fe(002)system,both the DMI and its related SOC energy are concentrated at the interfacial Fe *** investigation will provide a valuable insight into the spintronic community in exploring novel devices with chirality dependence.

关键词： Fe/Pt i-DMI BLS ferromagnetic resonance magnetic relaxation

A time-dependent luminescent phosphor of Na_(2)Ba_(2)Si_(2)O_(7):Eu for multi-level encryption and dynamic information display

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Journal of Advanced Ceramics 2024年第4期13卷 429-436页

作者： Jie Shao Xiyang Li Meng Liu Haiqin Sun Qiwei Zhang Dengfeng Peng Fuchi Liu College of physics and Technology Guangxi Normal UniversityGuilin 541004China Guangxi Key laboratory of Nuclear physics and Technology Guangxi Normal UniversityGuilin 541004China Key laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

Photo-stimuli responsive materials show great potential in the fields of information encryption and storage due to their distinctive spatial or temporal color ***,the conventional single or multi-color static outputs by light stimulus difficulty meet practical requirements for high-security optical storage ***,a novel dynamic irradiation-responsive phosphor of Na_(2)Ba_(2)Si_(2)O_(7):Eu is demonstrated,exhibiting high storage stability and convenient readout *** inherent Eu^(2+)luminescence can be dynamically tuned,instantly read out,and conveniently erased by controlling irradiation duration of a portable diode laser(365 nm).The modulation mechanism is unraveled by optically induced oxidation reactions of Eu^(2+)→Eu^(3+)and defects as killer *** excellent luminescence modulation degree(ΔR_(t)=89.5%)and the accompanying larger color contrast enable the creation of invisible optical codes with multi-level encryption in bright or dark *** results indicate potential applications of Na_(2)Ba_(2)Si_(2)O_(7):-based materials in information encryption and invisible optical storage,and are expected to expand more investigations on optically induced PL modulation behaviors based on mixed valences and defects.

关键词： light irradiation luminescent modulation invisible optical storage

Observation of parabolic electron bands on superconductor LaRu2As2

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Chinese physics B 2024年第7期33卷 70-75页

作者：周兴泰李更潘禄禄陈子超李萌时延昊杨海涛高鸿钧 Beijing National Center for Condensed Matter physics and Institute of physics Chinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences Hefei National laboratory

Ru-based superconductor LaRu2As2has been discovered exhibiting the highest critical temperature of ～ 7.8 K among iron-free transition metal pnictides with the ThCr2Si2-type crystal structure. However, microscopic research on this novel superconducting material is still lacking. Here, we utilize scanning tunneling microscopy/spectroscopy to uncover the superconductivity and surface structure of LaRu2As2. Two distinct terminating surfaces are identified on the cleaved crystals, namely, the As surface and the La surface. Atomic missing line defects are observed on the La surface. Both surfaces exhibit a superconducting gap of ～ 1.0 me V. By employing quasiparticle interference techniques, we observe standing wave patterns near the line defects on the La atomic plane. These patterns are attributed to quasiparticle scattering from two electron type parabolic bands.

关键词： superconductivity line defect quasi-particle scattering electron band

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Zero thermal expansion in Cs_(2)W_(3)O_(10)

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Chinese Chemical Letters 2024年第7期35卷 538-541页

作者： Juan Guo Mingyuan Fang Qingsong Liu Xiao Ren Yongqiang Qiao Mingju Chao Erjun Liang Qilong Gao School of physics&Microelectronics Key Laboratory of Materials Physics of Ministry of Education of ChinaZhengzhou UniversityZhengzhou 450052China

Zero thermal expansion materials are important for the practical applications due to their shape stability as changing *** reported concept of average atomic volume is an available method to hunt new zero thermal expansion ***,according to this concept,a tetragonal tungstate Cs_(2)W_(3)O_(10)with zero expansion has been *** is no structure phase transition as increasing temperature from 150 K to 573 *** coefficient of thermal expansion of axes and volume areαa=0.0074×10^(-6)K^(-1),αc=1.63×10^(-6)K^(-1),andαV=1.60×10^(-6)K^(-1),respectively,in the temperature range of 150~573 *** temperature-and pressure-dependent Raman spectra reveal that the vibrations of WO6octahedra libration modes with positive total anharmonicity and W-O-W bending mode with negative Grüneisen parameter are possibly the origin of zero thermal expansion in Cs_(2)W_(3)O_(10).

关键词： Zero thermal expansion Cesium tungstate Raman spectra Average atomic volume Temperature-dependent X-ray diffraction

Highly efficient room temperature phosphorescent liquid crystalline polymer optical waveguides for advanced optoelectronics

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Science China Chemistry 2024年第10期67卷 3450-3457页

作者： Jie Li Yan Guan Wei Xia Jin-Kang Chen Jiang Huang Yi Chen Qi Lin Er-Qiang Chen He-Lou Xie Key laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education and Key Laboratory of Advanced Functional Polymer Materials of CollegesUniversities of Hunan Province and College of ChemistryXiangtan University Beijing National laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking University School of physics and Optoelectronics Xiangtan University

Active organic optical waveguide materials(OOWMs) incorporating room temperature phosphorescence(RTP) hold significant promise for diverse applications in photonic and optoelectronic devices. Despite this potential, realizing active RTP optical waveguides with large-sized ordered structures and minimal light loss remains a formidable challenge. To address this issue, we present a groundbreaking thermoplastic active OOWM with low light loss, leveraging room temperature phosphorescent liquid crystalline polymer(LCP). This innovative material can be easily synthesized through the copolymerization of phosphorescent and liquid crystalline monomers. The resulting RTP copolymer exhibits a nematic liquid crystal phase with a phosphorescence lifetime of approximately 0.15 ms and an afterglow duration of around 1 second. Leveraging the excellent processability of LCP,we successfully produce meter-scale fibers via melt spinning. These RTP LCP fibers, characterized by a high orientation of mesogens along the fiber axis, demonstrate superior light confinement and efficient light conduction compared to unoriented samples, resulting in a low optical loss coefficient of 0.13 dB/mm. Furthermore, the thermal responsiveness of the RTP LCP optical waveguide enables its use as a photo switch. This pioneering work paves the way for the design of new OOWMs tailored for advanced photonics and optoelectronics devices.

关键词： room temperature phosphorescence liquid crystalline polymer active optical waveguide

Production and test of sPHENIX W/SciFiber electromagnetic calorimeter blocks in China

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Nuclear Science and Techniques 2024年第8期35卷 167-176页

作者： Xiao‑Zhou Yu Xi‑Yang Wang Wei‑Hu Ma Shi‑Hong Fu Peng‑Fei Sun Jin‑Xing Song Wan‑Bing He Yang Shen Long Ma Jin‑Hui Chen Huan‑Zhong Huang Si‑Guang Wang Jing Zhou Xiao‑Mei Li Institute of Modern physics Fudan UniversityShanghai 200433China Key laboratory of Nuclear physics and Ion‑Beam Application(MOE) Fudan UniversityShanghai 200433China Science and Technology on Nuclear Data laboratory China Institute of Atomic EnergyBeijing 102413China Department of physics and Astronomy University of CaliforniaLos AngelesCA 90095USA State Key laboratory of Nuclear physics and Technology School of PhysicsPeking UniversityBeijing 100871China

The sPHENIX experiment is a new generation of large acceptance detectors at the relativistic heavy ion collider at Brookhaven National laboratory,with scientific goals focusing on probing the strongly interacting Quark–Gluon plasma with hard probes of jets,open heavy flavor particles,andγ*** EMCal detector,which covers the pseudo-rapidity region of|η|≤1.1,is an essential subsystem of *** this study,we focused on producing and testing EMCal blocks covering a pseudo-rapidity of|η|∈[0.8,1.1].These,in conjunction with the central pseudo-rapidity EMCal blocks,significantly enhance the sPHENIX physics capability of the jet andγparticle *** this paper,the detector module production and testing of sPHENIX W-powder/scintillating fiber(W/ScFi)electromagnetic calorimeter blocks are *** selection of the tungsten powder,mold fabrication,QA procedures,and cosmic ray test results are discussed.

关键词： sPHENIX Tungsten/scintillating fiber electromagnetic calorimeter Cosmic ray test

Signature of Superconductivity in Pressurized La_(4)Ni_(3)O_(10)

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Chinese physics Letters 2024年第1期41卷 77-84页

作者：李庆张英杰项浙宁张宇航祝熙宇闻海虎 National laboratory of Solid State Microstructures and Department of physics Center for Superconducting Physics and MaterialsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

The discovery of high-temperature superconductivity near 80K in bilayer nickelate La_(3)Ni_(2)O_(7)under high pressures has renewed the exploration of superconducting nickelate in bulk *** extension of superconductivity in other nickelates in a broader family is also ***,we report the experimental observation of superconducting signature in trilayer nickelate La_(4)Ni_(3)O_(10)under high *** using a modified solgel method and post-annealing treatment under high oxygen pressure,we successfully obtained polycrystalline La_(4)Ni_(3)O_(10)samples with different transport behaviors at ambient *** we performed high-pressure electrical resistance measurements on these samples in a diamond-anvil-cell ***,the signature of possible superconducting transition with a maximum transition temperature(T_(c))of about 20K under high pressures is observed,as evidenced by a clear drop of resistance and the suppression of resistance drops under magnetic *** the resistance drop is sample-dependent and relatively small,it appears in all of our measured *** argue that the observed superconducting signal is most likely to originate from the main phase of La_(4)Ni_(3)O_(10).Our findings will motivate the exploration of superconductivity in a broader family of nickelates and shed light on the understanding of the underlying mechanisms of high-T_(c) superconductivity in nickelates.

关键词： materials superconductivity signature

Virtual source approach for maximizing resolution in high-penetration gamma-ray imaging

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Matter and Radiation at Extremes 2024年第3期9卷 19-30页

作者： Yuchi Wu Shaoyi Wang Bin Zhu Yonghong Yan Minghai Yu Gang Li Xiaohui Zhang Yue Yang Fang Tan Feng Lu Bi Bi Xiaoqin Mao Zhonghai Wang Zongqing Zhao Jingqin Su Weimin Zhou Yuqiu Gu National Key laboratory of Plasma physics Laser Fusion Research CenterCAEPMianyangSichuan 621900China College of physics Sichuan UniversityChengdu 610065China

High-energy gamma-ray radiography has exceptional penetration ability and has become an indispensable nondestructive testing(NDT)tool in various *** high-energy photons,point projection radiography is almost the only feasible imaging method,and its spatial resolution is primarily constrained by the size of the gamma-ray *** conventional industrial applications,gamma-ray sources are commonly based on electron beams driven by accelerators,utilizing the process of bremsstrahlung *** size of the gamma-ray source is dependent on the dimensional characteristics of the electron *** research has been conducted on various advanced accelerator technologies that have the potential to greatly improve spatial resolution in *** our investigation of laser-driven gamma-ray sources,a spatial resolution of about 90μm is achieved when the areal density of the penetrated object is 120 g/cm^(2).A virtual source approach is proposed to optimize the size of the gamma-ray source used for imaging,with the aim of maximizing spatial *** this virtual source approach,the gamma ray can be considered as being emitted from a virtual source within the convertor,where the equivalent gamma-ray source size in imaging is much smaller than the actual emission *** the basis of Monte Carlo simulations,we derive a set of evaluation formulas for virtual source scale and gamma-ray emission *** optimal conditions,the virtual source size can be as small as 15μm,which can significantly improve the spatial resolution of high-penetration imaging to less than 50μm.

关键词： resolution approach utilizing

Reanalysis of energy band structure in the type-II quantum wells

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Chinese physics B 2024年第6期33卷 75-78页

作者：李欣欣邓震江洋杜春花贾海强王文新陈弘 Key laboratory for Renewable Energy Beijing Key Laboratory for New Energy Materials and DevicesBeijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China Center of Materials and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China The Yangtze River Delta physics Research Center Liyang 213000China Songshan Lake Materials laboratory Dongguan 523808China

Band structure analysis holds significant importance for understanding the optoelectronic characteristics of semiconductor structures and exploring their potential applications in practice. For quantum well structures, the energy of carriers in the well splits into discrete energy levels due to the confinement of barriers in the growth direction. However, the discrete energy levels obtained at a fixed wave vector cannot accurately reflect the actual energy band structure. In this work, the band structure of the type-II quantum wells is reanalyzed. When the wave vectors of the entire Brillouin region(corresponding to the growth direction) are taken into account, the quantized energy levels of the carriers in the well are replaced by subbands with certain energy distributions. This new understanding of the energy bands of low-dimensional structures not only helps us to have a deeper cognition of the structure, but also may overturn many viewpoints in traditional band theories and serve as supplementary to the band theory of low-dimensional systems.

关键词： energy band structure type-II quantum wells low-dimensional semiconductors