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Two-Dimensional Electron Gas with High Mobility Forming at BaO/SrTiO_(3) Interface

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Chinese Physics Letters 2022年第4期39卷 41-46页

作者： Cheng Cao Shengru Chen Jun Deng gang Li Qinghua Zhang Lin Gu Tian-Ping Ying Er-Jia guo jian-gang guo Xiaolong Chen Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 101408China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China

Two-dimensional electron gas(2DEG)with high electron mobility is highly desired to study the emergent properties and to enhance future device *** we report the formation of 2DEG with high mobility at the interface between rock-salt Ba O and perovskite Sr Ti O_(3).The interface consists of the ionically compensated Ba O_(1-δ) layer and the electronically compensated Ti O_(2) layer,which is demonstrated as a perfect interface without lattice *** so-formed interface features metallic conductivity with ultralow square resistance of7.3×10^(-4)Ω/□at 2 K and high residual resistance ratios R_(300 K)/R_(2 K) up to *** electron mobility reaches69000 cm^(2)·V^(-1)·s^(-1)at 2 K,leading to Shubnikov–de Haas oscillations of *** functional theory calculations reveal that the effective charge transfers from Ba O to the Ti 3d_(xy) orbital occur at the interface,leading to the conducting Ti O_(2) *** work unravels that Ba O can adapt itself by removing oxygen to minimize the lattice mismatch and to provide substantial carriers to Sr Ti O_(3),which is the key to forming 2DEGs with high mobility at the interfaces.

关键词： interface Electron resistance

Structural modulation and physical properties of cobalt-doped layered La_(2)M_5As_(3)O_(2)(M=Cu,Ni)compounds

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Chinese Physics B 2021年第7期30卷 394-400页

作者： Lei Yang Yan-Peng Song Jun-Jie Wang Xu Chen Hui-Jing Du jian-gang guo Key Laboratory for Microstructural Material Physics of Hebei Province School of ScienceYanshan UniversityQinhuangdao 066004China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China

We investigate the structural variation and physical properties of layered La_(2)M_5As_(3)O_(2)(M=Cu,Ni)compound upon Co *** is found that the substitution of Co ion just induces the monotonous change of lattice constants without observing the anomalous kink in superconducting La_(2)(Cu_(1-x)Nix)_(5)As_(3)O_(2)***,this doping barely changes As–As bond length in[M_(5)As_(3)]^(2-)subunit(±2%),being significantly smaller than 7%shrinkage of that in La_(2)(Cu_(1-x)Nix)_(5)As_(3)O_(2).Therefore,the doping dependence of crystal structure exhibits similar trend with Ba_(1-x)K_xFe_(2)As_(2)without the interference of As1–As 2 bonding,implying that the Co substitution for Cu/Ni is *** terms of physical property,La_(2)(Cu1-xCox)~5As_(3)O_(2)turns into itinerant ferromagnetic metal,while La_(2)(Ni_(1-x)Co_(x))_(5)As_(3)O_(2)shows paramagnetism and suppressed structural phase transition upon *** distinct structural variation and absence of superconductivity provide important clues to understand the effect of As–As bond in[M_(5)As_(3)]^(2-)subunit.

关键词： crystal structure As–As covalent bond transport property

Highly Robust Reentrant Superconductivity in CsV_3Sb_5 under Pressure

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Chinese Physics Letters 2021年第5期38卷 114-120页

作者： Xu Chen Xinhui Zhan Xiaojun Wang Jun Deng Xiao-Bing Liu Xin Chen jian-gang guo Xiaolong Chen Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Laboratory of High Pressure Physics and Material Science(HPPMS) School of Physics and Physical EngineeringQufu Normal UniversityQufu 273100China Songshan Lake Materials Laboratory Dongguan 523808China

We present the superconducting(SC) property and high-robustness of structural stability of kagome CsV_3Sb_5 under in situ high *** the initial SC-I phase,its T_c is quickly enhanced from 3.5 K to 7.6 K and then totally suppressed at P-10 *** further increasing pressure,an SC-Ⅱ phase emerges at P-15 GPa and persists up to 100 *** T_c rapidly increases to the maximal value of 5.2 K at P=53.6 GPa and slowly decreases to 4.7 K at P=100 GPa.A two-dome-like variation of T_c in CsV_3Sb_5 is concluded *** Raman measurements demonstrate that weakening of E_(2g) mode and strengthening of E_(1g) mode occur without phase transition in the SC-II phase,which is supported by the results of phonon spectra *** structure calculations reveal that exertion of pressure may bridge the gap of topological surface nontrivial states near E_F,i.e.,disappearance of Z2 ***,the Fermi surface enlarges significantly,consistent with the increased carrier *** findings here suggest that the change of electronic structure and strengthened electron-phonon coupling should be responsible for the pressure-induced reentrant SC.

关键词： Highly Robust Reentrant Superconductivity in CsV_3Sb_5 under Pressure

Nodeless superconductivity in a quasi-two-dimensional superconductor AuTe2Se(4/3)

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Chinese Physics B 2018年第6期27卷 87-91页

作者： Xiao-Yu Jia Yun-Jie Yu Xu Chen jian-gang guo Tian-Ping Ying Lan-Po He Xiao-Long Chen Shi-Yan Li State Key Laboratory of Surface Physics Department of Physics and Laboratory of Advanced Materials Fudan UniversityBeijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of SciencesSchool of Physical Sciences University of Chinese Academy of SciencesCollaborative Innovation Center of Quantum MatterCollaborative Innovation Center of Advanced Microstructure

We performed ultra-low temperature thermal conductivity measurements on the single crystal of a new gold-based quasi-two-dimensional superconductor Au Te2Se（4/3）, which has a superconducting transition temperature Tc = 2.70 K. A negligible residual linear term κ0/T in zero magnetic field is observed, which suggests fully gapped superconducting ***, the field dependence of κ0/T is similar to that of the multi-band s-wave superconductor Ba Fe1.9 Ni0.1 As2 at low field. These results reveal multiple nodeless superconducting gaps in this interesting quasi-two-dimensional superconductor with Berezinsky–Kosterlitz–Thouless topological transition.

关键词： superconductivity thermal transport measurement gap structure two-dimensional material

Crystal structures and sign reversal Hall resistivities in iron-based superconductors Lix(C3H10N2)0.32FeSe（0.15

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Chinese Physics B 2019年第6期28卷 389-402页

作者： Rui-Jin Sun Shi-Feng Jin Jun Deng Mu-Nan Hao Lin-Lin Zhao Xiao Fan Xiao-Ning Sun jian-gang guo Lin Gu Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Physical Sciences University of Chinese Academy of SciencesBeijing 101408China

Heavy electron-doped FeSe-derived materials have attracted attention due to their uncommon electronic structures with only ‘electron pockets’, and they are different from other iron-based superconductors. Here, we report the crystal structures, superconductivities and normal state properties of two new Li-doped FeSe-based materials, i.e.,Li0.15(C3H10N2)0.32 FeSe(P-4) and Lix(C3H10N2)0.32 FeSe(P4/nmm, 0.25 < x < 0.4) with superconducting transition temperatures ranging from 40 K to 46 K. The determined crystal structures reveal a coupling between Li concentration and the orientation of 1,3-diaminopropane molecules within the largely expanded FeSe layers. Superconducting fluctuations appear in the resistivity of the two superconductors and are fitted in terms of the quasi two-dimensional(2 D) Lawrence–Doniach model. The existence of a crossing point and scaling behavior in the T-dependence of diamagnetic response also suggests that the two superconductors belong to the quasi-2 D system. Interestingly, with the increase of temperature, a sign of Hall coefficient(RH) reversing from negative to positive is observed at ~185 K in both phases, suggesting that‘hole pockets’ emerge in these electron-doped FeSe materials. First principle calculations indicate that the increase in FeSe layer distance will lift up a ‘hole band’ associated with dx2-y2 character and increase the hole carriers. Our findings suggest that the increase in two dimensionalities may lead to the sign-reversal Hall resistivity in Lix(C3H10N2)0.32 FeSe at high temperature.

关键词： superconductor Lawrence–Doniach model dimensionality

Discovery of Two Families of VSb-Based Compounds with V-Kagome Lattice

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Chinese Physics Letters 2021年第12期38卷 44-49页

作者： Yuxin Yang Wenhui Fan Qinghua Zhang Zhaoxu Chen Xu Chen Tianping Ying Xianxin Wu Xiaofan Yang Fanqi Meng gang Li Shiyan Li Lin Gu Tian Qian Andreas PSchnyder jian-gang guo Xiaolong Chen 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 Max-Planck-Institut für Festkörperforschung Heisenbergstrasse 1D-70569 StuttgartGermany State Key Laboratory of Surface Physics Department of PhysicsFudan UniversityShanghai 200438China School of Materials Tsinghua UniversityBeijing 100084China Songshan Lake Materials Laboratory Dongguan 523808China

We report the structure and physical properties of two newly discovered compounds AV_(8)Sb_(12)and AV_(6)Sb_(6)(A=Cs,Rb),which have C_(2)(space group:Cmmm)and C_(3)(space group:R3 m)symmetry,*** basic Vkagome unit appears in both compounds,but stacking ***_(2)Sb_(2) layer is sandwiched between two V_(3)Sb_(5)layers in AV_(8)Sb_(12),altering the V-kagome lattice and lowering the symmetry of kagome layer from hexagonal to *** AV_(6)Sb_(6),the building block is a more complex slab made up of two half-V_(3)Sb_(5)layers that are intercalated by Cs cations along the *** property measurements demonstrate that both compounds are nonmagnetic metals,with carrier concentrations at around 10^(21)cm^(-3).No superconductivity has been observed in CsV_(8)Sb_(12)above 0.3 K under in situ pressure up to 46 *** to CSV_(3)Sb_(5),theoretical calculations and angle-resolved photoemission spectroscopy reveal a quasi-two-dimensional electronic structure in CsV_(8)Sb_(12)with C_(2)symmetry and no van Hove singularities near the Fermi *** findings will stimulate more research into V-based kagome quantum materials.

关键词： symmetry Lattice hexagonal

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基于塑料机械的标准指标库研究

塑料工业 2018年第10期46卷 132-135页

作者：吴建港国玉宝宁波市标准化研究院浙江宁波315041

介绍了塑料机械的行业和标准化现状,并提出构建塑机标准体系。以标准体系为基础,梳理"标准体系-标准-产品-指标项-指标值"的标准指标库模型,为进一步开展标准指标比对奠定基础。

关键词：塑料机械标准指标库标准指标比对

Surface microstructures of lunar soil returned by Chang’e-5 mission reveal an intermediate stage in space weathering process

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Science Bulletin 2022年第16期67卷 1696-1701,M0004页

作者： jian-gang guo Tianping Ying Hanbin Gao Xu Chen Yanpeng Song Ting Lin Qinghua Zhang Qiang Zheng Chunlai Li Yigang Xu Xiaolong Chen Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences(CAS)Beijing 100190China CAS Key Laboratory of Standardization and Measurement for Nanotechnology CAS Center for Excellence in NanoscienceNational Centre for Nanoscience and TechnologyBeijing 100190China Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China

The lunar soils evolution over time is mainly caused by space weathering that includes the impacts of varying-sized meteoroids and charged particles implantation of solar/cosmic winds as *** has long been established that space weathering leads to the formation of outmost amorphous layers(50–200 nm in thickness)embedded nanophase iron(npFe^(0))around the mineral fragments,albeit the origin of the npFe^(0) remains *** Chang’e-5(CE-5)mission returned samples feature the youngest mare basalt and the highest latitude sampling site,providing an opportunity to seek the critical clues for understanding the evolution of soils under space ***,we report the surface microstructures of the major minerals including olivine,pyroxene,anorthite,and glassy beads in the lunar soil of *** the previous observations,only olivine in all crystals is surrounded by a thinner outmost amorphous SiO_(2) layer(∼10 nm thick)and embedded wüstite nanoparticles FeO(np-FeO,3–12 nm in size)instead of npFe^(0).No foreign volatile elements deposition layer and solar flare tracks can be found on the surface or inside the olivine and other *** unique rim structure has not been reported for any other lunar,terrestrial,Martian,or meteorite samples so *** observation of wüstite FeO and the microstructures support the existence of an intermediate stage in space weathering for lunar minerals by thermal decomposition.

关键词： Lunar soil Wüstite FeO Nanoparticle Nanophase Fe Amorphous rim

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我国企业年金投资监管模式选择

特区经济 2009年第5期244卷 227-229页

作者：田建刚唐国林中国民航飞行学院人事处四川广汉618307

随着我国老龄化程度的加深,企业年金作为养老保险的第二支柱越来越受到人们的关注,我国先后制定了《企业年金试行办法》和《企业年金基金管理试行办法》等一系列文件。本文首先对现有的两种企业年金投资监管模式进行了简要介绍,然后针... 详细信息

随着我国老龄化程度的加深,企业年金作为养老保险的第二支柱越来越受到人们的关注,我国先后制定了《企业年金试行办法》和《企业年金基金管理试行办法》等一系列文件。本文首先对现有的两种企业年金投资监管模式进行了简要介绍,然后针对我国目前实行的企业年金投资监管模式存在的问题进行了深入分析,并在此基础上提出了完善措施,这对于进一步规范我国企业年金的投资监管,保障企业员工的基本生活具有现实意义。

关键词：企业年金投资监管监管模式