Beamline introduction
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The SSRF BL07U Spatial-resolved and Spin-resolved ARPES and Magnetism Beamline is a new extreme ultraviolet and soft X-ray beamline at the Shanghai Synchrotron Radiation Facility. Beamline is aimed at the nano-resolved angle resolved photoemission spectroscopy (Nano-ARPES), spin-resolved angle resolved photoemission spectroscopy (Spin-ARPES), X-ray magnetic circular dichroism (XMCD) and X-ray magnetic linear dichroism (XMLD) techniques for certain scientific research. The beamline based on a pair of elliptical polarized undulators (EPUs) and a variable-included-angle plane grating monochromator, delivers circularly polarized or linear polarized X-ray within the energy range 50-2000 eV. While the beamline has two branches: one dedicated to Nano-ARPES, which has a minimum spot size only ~200 nm, another branch consisted of the Spin-ARPES, Vector magnetic field and Supercondictive magnetic field end-stations.
Scientific Scope
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The SSRF BL07U Spatial-resolved and Spin-resolved ARPES and Magnetism Beamline mainly have four experimental stations, which is targeting the featured angle-resolved photoelectron spectroscopy and soft X-ray magnetic circular dichroism and magnetic line dichroism experimental techniques.
The principle of Angle-resolved photoemission spectroscopy (ARPES) is based on the photoelectric effect: when X-rays are irradiated on the sample surface, the electrons inside the sample absorb the photon energy and escape from the surface of the material, generating photoelectrons. In this process, the energy is conserved and the momentum is conserved. The energy and number of photoelectrons in the space without using angle can be measured by the energy analyzer, and the information of energy and momentum of the electrons inside the material can be obtained. With the development of spatially resolved ARPES technology by the synchrotron radiation, the development of featured ARPES technology is imperative. The objective of Nano-ARPES is to micro-focus the synchrotron radiation light to sub-micrometer/hundred nanometer or even smaller beam size, together with the design of high-stability samples manipulator and the relative rotation of the energy analyzer with the sample, to obtain the ARPES measurements of the electronic structure with high spatial resolution. Based on the related technology, it is of great significance to study the electronic structure of the following samples: 1) samples with strong lattice three-dimensionality, poor dissociation and more disordered dissociation surfaces; 2) samples with multiple dissociation surfaces or spatial phase separation; 3) small-sized samples such as nano-sheets, nano rods, nano wires, etc., which are obtained by mechanical stripping, CVD growth, and so on; 4) micro-nano electronic devices, etc., which are prepared by micro-nano processing technology. The Spin-ARPES station is designed to study the correlation interactions and spin-orbit coupling of electron spins. The BL07U Spin-ARPES station is equipped with a Scienta Omicron DA30L energy analyzer and a new generation of VLEED reflectance image-based electron spin analyzer.
Additionally, the BL07U contains two experimental stations for soft X-ray magnetic dichroism measurements: the Octupole Electromagnet Station and the Superconducting Magnetic Field Station. Both stations provide in-situ cryogenic and magnetic fields for measuring soft X-ray near-edge absorption spectra and magnetic circular/linear dichroism with high signal-to-noise ratios. Magnetic dichroism is elementally selective, distinguishes between spin and orbital magnetic moment contributions to magnetism, and is an irreplaceable means of studying magnetism and spintronics.
 
• Materials Science (Magnetism, Magnetic Materials and Devices, Nanomaterials, Surface Physical Properties, Superconductivity, High Temperature Superconductivity)
• Correlation Electron Spectroscopy (Low-dimensional Materials and Devices, Topological Materials, Electronic Structures)
• Condensed matter physics
• Solid-state Physics
Beamline Layout
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Specifications
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 Energy Range  50-2000 eV
 Energy resolution  9000 @867 eV
 15000 @91 eV
 Spot size at sample point  200 × 200 nm2 @91 eV (Nano-ARPES)
 150 × 50 nm2 @867 eV (Spin-ARPES)
 120 × 50 nm2 @867 eV (Focus spot size)
 600 × 100 nm2 @867 eV (Non-focus mode)
 Photon flux at sample point  (phs/s/0.01%BW, 300mA)>1 × 1012 phs/s/0.01%BW @867eV (Spin-ARPES/XMCD)
 >1 × 1010 phs/s/0.01%BW @91eV (Nano-ARPES)
Endstations
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1.Vector-magnetic field endstation 
• Magnetic field: 0.9T (maximum, spindle directions); 0.6T(maximum, arbitrary directions)
• Temperature working range: 15-400K
• Sample stage movement freedom: vertical direction and rotate.
• TEY and TFY 
• In-situ bias test kit
 
2.Superconductive magnetic field endstation
• Magnetic field: 9T (maximum, horizontal plane along X-ray); 4T(maximum, vertical to X-ray at horizontal plane);2.5T(maximum, arbitrary directions in horizontal plane)
• Temperature working range: 4-325K
• Sample stage movement freedom: vertical direction and rotate.
• TEY
• Focus spot size:80*60um
 
3.Nano-ARPES endstation: Angle-resolved photoelectron spectroscopy with spatial resolution capability
• Sample testing chamber rotation range:±15°
• Sample rotation range:±15°
• Sample spot size:200nm×200nm
• Spectrometer energy resolution:≤ 10meV@91eV
 
4.Spin-AREPS endstation: Probing the electronic spin structure of materials
• Spectrometer energy resolution:≤ 30meV@91eV
• Momentum resolution: 0.5°;
• Total spin analyzer efficiency: > 40
 
5.Picosecond time resolution testing chamber
• Synchronize the accelerator frequency
• In-situ magnetic field, microwave filed
• Minimum time delay adjustment: 5ps
• TEY and TFY
• Temperature working range: 10-400K
Data Acquisition and Analysis
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The software of beamline control system is developed with EPICS (Experimental Physics and Industrial Control System) package. According to the distributed feature of EPICS, the hardware includes three layers: an operator interface (OPI), an input/output controller (IOC) and drivers or monitors. The OPI is a HP-PC running the operator interfaces with Linux operating system and EPICS up-level tools. The whole system runs stably and provides flexible working environment for user requirements.