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Significantly enhanced superconductivity in monolayer FeSe films on SrTiO3（001） via metallic δ-doping

National Science Review 2024年第3期11卷 119-127页

作者： Xiaotong Jiao Wenfeng Dong Mingxia Shi Heng wang Cui Ding Zhongxu Wei Guanming Gong Yanan Li Yuanzhao Li Binjie Zuo Jian wang Ding Zhang Minghu Pan Lili wang Qi-Kun Xue State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University School of Physics&Information Technology Shaanxi Normal University beijing Academy of Quantum Information Sciences department of Physics Southern University of Science and Technology International Center for Quantum Materials School of Physics Peking University department of Physics The Pennsylvania State University Collaborative Innovation Center of Quantum Matter Hefei National Laboratory

Superconductivity transition temperature（Tc） marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at Tc, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii–Kosterlitz–Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3（001）, although the pairing temperature（Tp） is revealed to be 65–83 K by using spectroscopy characterization, the measured zero-resistance temperature（Tc0） is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3（001） surface, in which Tc0is enhanced by 12 K with a narrowed transition width ΔTc～8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3（001） surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.

关键词： monolayer FeSe interface superconductivity δ-doping zero-resistance temperature superconductivity transition temperature

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A New Discrete Chirp Fourier Transform

A New Discrete Chirp Fourier Transform

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2002年第6届信号处理国际会议

作者： Pingyi Fan Chongxi Feng State Key Laboratory on Microwave and Digital Communications department of electronic Engineering tsinghua university {4. china 100084.

＜正＞ Discrete chirp Fourier transform （DCFT） can be used to match multiple chirp rates and constant frequency rates simultaneously. In this paper, we propose a new kind of DCFT scheme and investigate its matched filter properties. Compared to the DCFTs proposed previously, the new DCFT scheme keeps high chirp rate resolution on the detected signals and its signal detection range can cover the full signal space. Moreover, the robustness of the new DCFT on the chirp rate and constant frequency errors is investigated, and an explicit sufficient condition on the stability of the new DCFT with the chirp rate and constant frequency errors is presented.

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Study on Power Azimuth Spectrum of Wireless Channel in Microcell Environments

Study on Power Azimuth Spectrum of Wireless Channel in Micro...

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IEEE第14.国际个人无线移动通信大会

作者： TANG Ao GONG Ke The State Key Laboratory on Microwave and Digital Communications department of electronic Engineering tsinghua university {4. 100084.china

This paper discussed the spatial or angularspreading properties of wireless propagation in the urbanmicrocell environment, which is of great interests of futuremobile technology, especially in case of

关键词： power azimuth spectrum microcell environment

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Multichannel Resource Management of Integrated Communication and Broadcast Networks

Multichannel Resource Management of Integrated Communication...

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The 19th International Teletraffic Congress-ITC19

作者： MIAO Guowang NIU Zhisheng State Key Lab on Microwave and Digital Communications department of electronic Engineering tsinghua {4. Room 3-329. Building FIT tsinghua {4. beijing 100084.P.R. china State Key Lab on Microwave and Digital Communications department of electronic Engineering tsinghua {4. Room 3-327 Building FIT tsinghua {4. beijing 100084.P.R. china

＜正＞Broadcast network is potential for carrying services with both high data rate and high mobility. Combined with other media as a return channel, broadcast network can supply interactive data services. This paper proposes a multichannel architecture of integrated telecommunication and broadcast network to provide huge access bandwidth for multimedia information delivery while in fast moving. It can be a highly recommend-able candidate of future 4./5G communications. In order to fully employ all channels, the Multichannel Profit Oriented Allocation Method（MPOAM） is given for real-time multichannel bandwidth management. Simulation results powerfully show that MPOAM can both exploit the multichannel resources for near global profit maximization and provide effective QoS differentiation. Besides, the joint channel management outperforms the separate channel management greatly. The complexity of MPOAM is low enough for real time multichannel bandwidth management even for many joint channels.

关键词： multichannel broadcast integrated network resource management profit

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Study of Mode Characteristics for Equilateral Triangle Semiconductor Microlasers

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光学学报 2003年第S1期23卷 329-330页

作者： Qiao-Yin Lu, Xiao-Hong Chen, Wei-Hua Guo, Li-Juan Yu, Yong-Zhen Huang State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, beijing 100083, china, Tel: 010-82304.24. E-mail: luqy@redsemi.ac.cnJian wang and Yi LuoState Key Laboratory of Integrated Optoelectronics, department of electronic Engineering, tsinghua university, beijing 100084. china State Key Laboratory on IntegratedOptoelectronics Institute of SemiconductorsChinese Academy of Sciences P.O. Box 912 Beijing 100083China State Key Laboratory of Integrated Optoelectronics Department of Electronic EngineeringTsinghua University Beijing 100084China

InGaAsP semiconductor ETR microlasers with side length of 5 and 10 um are fabricated by ICP etching. The peaks in photoluminenscent spectra corresponding to longitudinal modes are observed with the interval consisting... 详细信息

关键词： for in on with ICP Study of Mode Characteristics for Equilateral Triangle Semiconductor Microlasers of

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A novel parameter estimation algorithm and its iterative extension for chirp signals

A novel parameter estimation algorithm and its iterative ext...

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2002年第6届信号处理国际会议

作者： Liping ZHANG Xiqin wang Yingning PENG Xiutan wang Xiang-gen Xia department of electronic Engineering {4. university beijing 100084.china department of ECE university of California Berkeley USA department of EC E university of Delaware DE USA

＜正＞ Chirp signal is a nonstationary signal that is often met in applications including radar and sonar etc. The parameter estimation of the unknown parameters in chirp signals by traditional maximum likelihood method or the open-loop optimum method bear some problems, such as the excessive computational complexity. We will propose a novel fast and robust method. The method is robust in the sense that it can be well suitable for the case of low signal to noise ratio（SNR）. For example, in the case of-10dB of SNR, the new method achieves a good performance quite close to that of the maximum likelihood method, and the computational complexity is reduced to only 1/4. of the original. We will present the motivation of the new algorithm and the performance analysis. Also some simulation results will be presented to illustrate its effectiveness.

关键词： Chirp rate estimation polynomial phase signal chirp signals

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Synthesis and Characterization of Radiate MgO Whiskers

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稀有金属材料与工程 2006年第S3期 648-649页

作者： Yanli Gong~1 Jianbao Li~1 Hong Lin~1 Xiaozhan Yang~1 Xuguang Tong~1 Xiangdong Huang~2 (1.State Key Laboratory of New Ceramics and Fine Processing,department of Materials Science and Engineering,tsinghua university,beijing 100084.{4.) (2.department of Materials Science and Engineering,Fuzhou university,Fuzhou 350002,{4.)

In this paper,radiate MgO whiskers were fabricated in the system of Mg-B-NaCl-Ar at relatively low temperature. The Mg vapor reacted with trace O2contained in the reaction system and formed MgO *** appropriate conditions,the MgO vapor could reach supersaturation and grow into highly radiate *** were characterized by means of field emission scanning electronic microscopy （FE-SEM）,transmission electronic microscopy （TEM） and energy dispersive spectrometer （EDS）.The mechanism of the morphologies of MgO was discussed.

关键词： MgO whiskers Synthesis

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Thermal conductivity of nanoscale thin nickel films

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Progress in Natural Science:Materials International 2005年第10期 60-67页

作者： YUAN Shiping and JIANG Peixue (Key Laboratory of Thermal Science and Power Engineering, department of Thermal Engineering, tsinghua university, beijing 100084. {4.) Key Laboratory of Thermal Science and Power Engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China

The inhomogeneous non-equilibrium molecular dynamics (NEMD) scheme is applied to model phonon heat conduction in thin nickel films. The electronic contribution to the thermal conductivity of the film is deduced from the electrical conductivity through the use of the Wiedemann-Franz law. At the average temperature of T = 300 K, which is lower than the Debye temperature (?)= 4.0 K, the results show that in a film thickness range of about 1 -11 nm, the calculated cross-plane thermal conductivity decreases almost linearly with the decreasing film thickness, exhibiting a remarkable reduction compared with the bulk value. The electrical and thermal conductivities are anisotropic in thin nickel films for the thickness under about 10 nm. The phonon mean free path is estimated and the size effect on the thermal conductivity is attributed to the reduction of the phonon mean free path according to the kinetic theory.

关键词： nanoscale nickel films thermal conductivity electrical conductivity.

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Measurement of the Thermal Conductivity of Undoped Polysilicon Thin Film Over 300K to 4.0K

Measurement of the Thermal Conductivity of Undoped Polysilic...

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2004.7th International Conference on Solid-State and Integrated Circuits Technology（ICSICT 2004.

作者： Zhichao Lv~(1*) Jiahui Yuan~2 Lilin Tian~1 Litian Liu~1 Zhijian Li~1 1 Institute of Microelectronics tsinghua university beijing 100084.{4. 2 department of electronic Engineering tsinghua university beijing 100084.{4.

＜正＞Polysilicon layers are widely used in microelectronic and microelectromechanical *** layer’s thermal parameters are very important for the design and fabrication of the ***,few literatures have investigated the polysilicon thin film’s lateral thermal conductivity,especially at the temperature between 300K and 4.0K,with the thickness less than *** work measures the lateral thermal conductivity of suspended undoped Low-Pressure Chemicial-Vaper Deposition （LPCVD）polysilicon layers,which are of 260nm and 200nm in *** measurement is performed by using steady-state Joule heating and electrical-resistance thermometer in patterned Platinum *** thermal conductivity is measured at three different temperatures. According to the measurement data,the thermal conductivity of the polysilicon thin films decrease with the reduction of the thin film’s ***,the thermal conductivity is almost invariable in the range from 300K to 4.0K.

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On the Equivalence between the rDCT and the DsCT Techniques

On the Equivalence between the rDCT and the DsCT Techniques

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第二十七届中国控制会议

作者： wang Xingxuan 1,Zheng Dazhong 2 1.department of electronic Engineering,Fudan university,Shanghai 2004.3,P.R.{4. 2.department of Automation,tsinghua university,beijing 100084.P.R.{4.

The two continuous variable dynamic systems（CVDS） based techniques,the reiterative difference control technique（rDCT） and the differences control technique（DsCT）,have been successively proposed and applied to a furnace system with multiple parallel passes for the system to be pass balancing,both of which have demonstrated many advantages over some advanced control approaches and given good application *** paper studies the problem of the equiva-lence between the two CVDS-based control *** first shows that the two techniques are equivalent to each other,then analyzes the equivalence factors of the two techniques for some different cases respectively,and finally points out that the equivalence factors might vary with a different number of the parallel passes.

关键词： Multi-passes furnace systems Pass balancing rDCT technique DsCT technique Equivalence Equivalence factor

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