从极化团簇的随机涨落出发,利用维纳过程模型,推导了铁电体中极化长程涨落的弛豫规律以及光强自相关函数所可能的表现形式.阐述了微观极化团簇的弛豫过程与宏观测量弛豫规律之间的联系.通过对原有氦氖激光光子关联谱实验装置进行改进,...从极化团簇的随机涨落出发,利用维纳过程模型,推导了铁电体中极化长程涨落的弛豫规律以及光强自相关函数所可能的表现形式.阐述了微观极化团簇的弛豫过程与宏观测量弛豫规律之间的联系.通过对原有氦氖激光光子关联谱实验装置进行改进,观测了BaTiO3和0.71Pb(Mg1/3Nb2/3)O3-0.29Pb Ti O3单晶中极化团簇长程涨落在居里点和立方到四方相变点附近的弛豫过程.在BaTiO3中发现极化团簇长程涨落在居里点之上4 K存在双弛豫现象,此现象与其有序无序相变机理相联系.在Pb(Mg1/3Nb2/3)O3-0.29PbTiO3中发现极化团簇长程涨落在相变点两侧都存在双弛豫现象.利用推导的理论结果很好地拟合了实验结果并提取了极化团簇长程涨落的弛豫时间.两种样品中极化团簇长程涨落的弛豫时间都在相变点出现突变,并呈现临界慢化现象.展开更多
The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution(< 30 nm) and high energy resolving power(>10 000...The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution(< 30 nm) and high energy resolving power(>10 000),for studying properties of solid, liquid, gas, film and other forms of materials at sub-micron scale. In this paper,we present a review on newly implemented techniques, such as total electron yield(TEY), dual energy contrast imaging, nano-CT, soft X-ray excited optical luminance(SXEOL), and coherent diffraction imaging(CDI)under development. Several research cases in nanomaterials, environmental science and biology are presented to demonstrate capabilities of the beamline.展开更多
High resolution Fresnel zone plates for nanoscale three-dimensional imaging of materials by both soft and hard x-rays are increasingly needed by the broad applications in nanoscience and nanotechnology.When the outmos...High resolution Fresnel zone plates for nanoscale three-dimensional imaging of materials by both soft and hard x-rays are increasingly needed by the broad applications in nanoscience and nanotechnology.When the outmost zone-width is shrinking down to 50 nm or even below,patterning the zone plates with high aspect ratio by electron beam lithography still remains a challenge because of the proximity effect.The uneven charge distribution in the exposed resist is still frequently observed even after standard proximity effect correction(PEC),because of the large variety in the line width.This work develops a new strategy,nicknamed as local proximity effect correction(LPEC),efficiently modifying the deposited energy over the whole zone plate on the top of proximity effect correction.By this way,50 nm zone plates with the aspect ratio from 4:1 up to 15:1 and the duty cycle close to 0.5 have been fabricated.Their imaging capability in soft(1.3 keV)and hard(9 keV)x-ray,respectively,has been demonstrated in Shanghai Synchrotron Radiation Facility(SSRF)with the resolution of 50 nm.The local proximity effect correction developed in this work should also be generally significant for the generation of zone plates with high resolutions beyond 50 nm.展开更多
The soft X-ray interference lithography(XIL) branch beamline at Shanghai Synchrotron Radiation Facility(SSRF) is briefly introduced in this article. It is designed for obtaining 1D(line/space) and 2D(dot/hole)periodic...The soft X-ray interference lithography(XIL) branch beamline at Shanghai Synchrotron Radiation Facility(SSRF) is briefly introduced in this article. It is designed for obtaining 1D(line/space) and 2D(dot/hole)periodic nanostructures by using two or more coherent extreme ultraviolet(EUV) beams from an undulator source. A transmission-diffraction-grating type of interferometer is used at the end station. Initial results reveal high performance of the beamline, with 50 nm half-pitch 1D and 2D patterns from a single exposure area of400 μm× 400 μm. XIL is used in a growing number of areas, such as EUV resist test, surface enhanced Raman scattering(SERS) and color filter plasmonic devices. By using highly coherent EUV beam, broadband coherent diffractive imaging can be performed on the XIL beamline. Well reconstructed pinhole of φ20 μm has been realized.展开更多
The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show ...The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.展开更多
文摘从极化团簇的随机涨落出发,利用维纳过程模型,推导了铁电体中极化长程涨落的弛豫规律以及光强自相关函数所可能的表现形式.阐述了微观极化团簇的弛豫过程与宏观测量弛豫规律之间的联系.通过对原有氦氖激光光子关联谱实验装置进行改进,观测了BaTiO3和0.71Pb(Mg1/3Nb2/3)O3-0.29Pb Ti O3单晶中极化团簇长程涨落在居里点和立方到四方相变点附近的弛豫过程.在BaTiO3中发现极化团簇长程涨落在居里点之上4 K存在双弛豫现象,此现象与其有序无序相变机理相联系.在Pb(Mg1/3Nb2/3)O3-0.29PbTiO3中发现极化团簇长程涨落在相变点两侧都存在双弛豫现象.利用推导的理论结果很好地拟合了实验结果并提取了极化团簇长程涨落的弛豫时间.两种样品中极化团簇长程涨落的弛豫时间都在相变点出现突变,并呈现临界慢化现象.
基金Supported by National Natural Science Foundation of China(Nos.11079050,11290165,11305252 and 11205232)Programs of the Chinese Academy of Sciences(Nos.KJCX2-EW-W09 and KJZD-EW-M03)+2 种基金the Open Research Project of the Large Scientific Facility of the Chinese Academy of Sciences:Study on Self-assembly Technology and Nanometer Array with Ultra-high Densitythe National Natural Science Foundation for Outstanding Young Scientists(No.11225527)the Shanghai Academic Leadership Program(No.13XD1404400)
文摘The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution(< 30 nm) and high energy resolving power(>10 000),for studying properties of solid, liquid, gas, film and other forms of materials at sub-micron scale. In this paper,we present a review on newly implemented techniques, such as total electron yield(TEY), dual energy contrast imaging, nano-CT, soft X-ray excited optical luminance(SXEOL), and coherent diffraction imaging(CDI)under development. Several research cases in nanomaterials, environmental science and biology are presented to demonstrate capabilities of the beamline.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1732104)China Postdoctoral Science Foundation(Grant No.2017M611443)Shanghai STCSM2019-11-20 Grant,China(Grant No.19142202700)。
文摘High resolution Fresnel zone plates for nanoscale three-dimensional imaging of materials by both soft and hard x-rays are increasingly needed by the broad applications in nanoscience and nanotechnology.When the outmost zone-width is shrinking down to 50 nm or even below,patterning the zone plates with high aspect ratio by electron beam lithography still remains a challenge because of the proximity effect.The uneven charge distribution in the exposed resist is still frequently observed even after standard proximity effect correction(PEC),because of the large variety in the line width.This work develops a new strategy,nicknamed as local proximity effect correction(LPEC),efficiently modifying the deposited energy over the whole zone plate on the top of proximity effect correction.By this way,50 nm zone plates with the aspect ratio from 4:1 up to 15:1 and the duty cycle close to 0.5 have been fabricated.Their imaging capability in soft(1.3 keV)and hard(9 keV)x-ray,respectively,has been demonstrated in Shanghai Synchrotron Radiation Facility(SSRF)with the resolution of 50 nm.The local proximity effect correction developed in this work should also be generally significant for the generation of zone plates with high resolutions beyond 50 nm.
基金Supported by the National Key Basic Research Program of China(No.2012CB825700)the Open Research Project of Large Scientific Facility from Chinese Academy of Sciences:Study on Self-Assembly Technology and Nanometer Array with Ultra-high Density
文摘The soft X-ray interference lithography(XIL) branch beamline at Shanghai Synchrotron Radiation Facility(SSRF) is briefly introduced in this article. It is designed for obtaining 1D(line/space) and 2D(dot/hole)periodic nanostructures by using two or more coherent extreme ultraviolet(EUV) beams from an undulator source. A transmission-diffraction-grating type of interferometer is used at the end station. Initial results reveal high performance of the beamline, with 50 nm half-pitch 1D and 2D patterns from a single exposure area of400 μm× 400 μm. XIL is used in a growing number of areas, such as EUV resist test, surface enhanced Raman scattering(SERS) and color filter plasmonic devices. By using highly coherent EUV beam, broadband coherent diffractive imaging can be performed on the XIL beamline. Well reconstructed pinhole of φ20 μm has been realized.
基金Supported by the National Basic Research Program of China under Grant Nos 2013CB921700,2015CB921300 and2015CB921301the National Natural Science Foundation of China under Grant Nos 11234014,11622435,11274362,11674371 and11474340+1 种基金the National Key Research and Development Program of China under Grant Nos 2016YFA0300300,2016YFA0300600,2016YFA0401000 and 2016YFA0400902the Open Large Infrastructure Research of Chinese Academy of Sciences,and the Pioneer Hundred Talents Program(Type C)of Chinese Academy of Sciences
文摘The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.
