Abstract: Magnetic imaging technology based on photo-emission electron microscopy (PEEM) has become an important and powerful tool for observing the magnetic domain in spintronics. The PEEM can get access to real-time imaging with high spatial resolution and is greatly sensitive to the spectroscopic information directly from the magnetic films and surfaces through photoemission process with variable excitation sources. Moreover, the breakthrough in the deep ultraviolet (DUV) laser technology makes it possible to realize domain imaging without the limitation of synchrotron radiation facilities or the direct excitation of photoelectrons due to the high enough photon energy of the source in the current threshold excitation study. In this review article, the deep ultraviolet photo-emission electron microscopy system is first introduced briefly. Then, a detailed study of the magnetic domain observation for the surface of L1〈sub〉0〈/sub〉-FePt films by the DUV-PEEM technique is presented, where a spatial resolution as high as 43.2 nm is successfully achieved. The above results clearly indicate that the DUV-PEEM reaches a level equivalent to the level reached by X-ray photoemission imaging technique. Finally, a series of recent progress of perpendicular FePt magnetic thin films obtained by the DUV-PEEM technique is provided in detail. For example, a stepped Cr seeding layer is used to form the large-area epitaxial FePt films with (001) and (111) two orientations, where magnetic linear dichroism (MLD) with large asymmetry is observed in the transition area of two phases. The signal of MLD is 4.6 times larger than that of magnetic circular dichroism. These results demonstrate that the magnetic imaging technology based on DUV-PEEM with excellent resolution ability will potentially become an important method to study magnetic materials in the future.

Abstract: It has been nearly 110 years since the discovery of superconductors, and more than 30 years since the discovery of high temperature superconductors (HTS). Great progress has been made in the application of superconducting electronics in the last two decades. HTS microwave devices have shown much higher perfomance than the traditional ones and have found their ways to the industry applications in mobile communication, radar, and special communication applications. Owing to the ultrahigh sensitivity to magnetic fields and currents, superconducting quantum interference devices (SQUIDs) have been used as the irresplacible sensors in geological surveying, magnetic resonanc imaging, biomagnetic imaging, and other areas. The sensitivity of superconducting radiation detectors such as superconducting SIS mixer, superconducting hot electron bolometer, superconducting transition edge sensor, superconducting nanowire single photon detector, and superconducting microwave kinetic inductance detector are near the quantum limitation. They are now key technology in geophysics, astrophysics, quantum information science, biomedicine, and so on. Superconducting Josephson parametric amplifier has become a key element for superconducting quantum computing. Superconducting integrated circuit has been included in the international roadmap for devices and systems, and shows that having the potential to become one of the mainstreams for post-Moore information processing technology. In metrology, superconducting Josephson effect and Josephson junction array devices have been widely used in the redefinition of quantum voltage reference and basic units of the International system of Units. Superconducting electronics plays an important role in the current quantum information technology boom, which in turn promotes the development of superconducting electronics. This review will brief introduce the research and application of superconducting electronics in China in recent years.

Abstract: Bi〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉-based alloys have been long regarded as the materials chosen for room temperature thermoelectric (TE) applications. With superior TE performances, Bi〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉-based bulk materials have been commercially used to fabricate TE devices already. However, bulk materials are less suitable for the requirements for applications of flexible or thin film TE devices, and therefore the thin film materials with advanced TE properties are highly demanded. Comparing with bulk materials and P-type Bi〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉-based thin films, the TE properties of N-type Bi〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉-based thin films have been relatively poor so far and need further improving for practical applications. In this study, a series of N-type Bi〈sub〉2〈/sub〉Te〈sub〉3〈i〉–〈/i〉〈/sub〉〈sub〉〈i〉x〈/i〉〈/sub〉Se〈sub〉〈i〉x〈/i〉〈/sub〉 thin films is prepared via magnetron sputtering method, and their structures can be precisely controlled by adjusting the sputtering conditions. Preferential layered growth of the Bi〈sub〉2〈/sub〉Te〈sub〉3–〈/sub〉〈sub〉〈i〉x〈/i〉〈/sub〉Se〈sub〉〈i〉x〈/i〉〈/sub〉 thin films along the (00l) direction is achieved by adjusting the substrate temperature and working pressure. Superior electrical conductivity over 10〈sup〉5〈/sup〉 S/m is achieved by virtue of high in-plane mobility. combining the advanced Seebeck coefficient of Bi〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉-based material with superior electrical conductivity of highly oriented Bi〈sub〉2〈/sub〉Te〈sub〉3–〈/sub〉〈italic/〉〈i〉〈sub〉x〈/sub〉〈/i〉Se〈sub〉〈i〉x〈/i〉〈/sub〉 thin film, a high power factor (PF) of the optimal Bi〈sub〉2〈/sub〉Te〈sub〉3–〈/sub〉〈sub〉〈i〉x〈/i〉〈/sub〉Se〈sub〉〈i〉x〈/i〉〈/sub〉 thin film can be enhanced to 42.5 μW/(cm·K〈sup〉2〈/sup〉) at room temperature, which is comparable to that of P-type Bi〈sub〉2〈/sub〉Te〈sub〉3〈/sub〉-based thin film and bulk material.

Abstract: 〈sec〉 Based on the wide-spectrum neutron beam (covering thermal neutrons and 〈i〉E〈/i〉 〉 10 MeV neutrons, with maximum energy of 1.6 GeV) provided by the China Spallation Neutron Source (CSNS), this paper focuses on the single event effect study of 14 nm FinFET large-capacity SRAM and 65 nm planar process SRAM device, using combined techniques of irradiation experiment, reverse analysis, and Monte-Carlo neutron transport simulation. The aim is to reveal the effect of integrated circuit process changing on the sensitivity of neutron induced single-bit and multiple-bit upsets (MBU), and to analyze the inner mechanisms, including the distribution of secondary particles in the sensitive volume, the characteristics of deposited charges, etc. 〈/sec〉〈sec〉 The results show that compared with the 65 nm device, single event upset (SEU) cross section of the 14 nm FinFET device, induced by 〈i〉E〈/i〉 〉 10 MeV neutrons, is reduced by about 40 times, while the MBU ratio increases from 2.2% to 7.6%, which is due to the reduction of sensitive volume size of the 14 nm FinFET device (80 nm × 30 nm × 45 nm), pitch, and critical charge (0.05 fC). The main forms of MBU are double-bit upset, triple-bit upset and quadruple-bit upset. Unlike the phenomenon that the 65 nm device is immune to thermal neutrons, the use of the 〈sup〉10〈/sup〉B element near M0 in the 14 nm FinFET device causes it to present the thermal neutron sensitivity to a certain extent. The SEU cross section induced by thermal neutrons is about 4.8 times smaller than that induced by 〈i〉E〈/i〉 〉 10 MeV neutrons. 〈/sec〉〈sec〉 Based on the device cross-section and memory area images obtained from the reverse analysis, a device model is established and neutron transport simulation based on Geant4 toolkit is carried out. The 〈i〉E〈/i〉 〉 10 MeV neutrons result in abundant secondary particle distribution in the sensitive volume of the device, covering n, p into even W. The neutron energy and presence or absence of the W plug near the sensitive volume have an importantinfluence on the type and probability of secondary particles in the sensitive volume. The analysis and calculations show that a large number of high-〈i〉Z〈/i〉 secondary particles with long range and large LET values generated by high-energy neutrons in the sensitive volume of the device are the inducement of MBU, and SEUs mainly result from the contribution of light ions such as p, He, and Si. 〈/sec〉

Abstract: As a major component in the air, nitrogen emits fluorescence when it interacts with intensive laser field. The fluorescence comes from the first negative band system (〈inline-formula〉〈tex-math id="M7"〉\begin{document}${{\rm{B}}^{{2}}}\Sigma _{\rm{u}}^{{ + }} \to {{\rm{X}}^{{2}}}\Sigma _{\rm{g}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M7.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M7.png"/〉〈/alternatives〉〈/inline-formula〉 transition) of 〈inline-formula〉〈tex-math id="M8"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M8.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M8.png"/〉〈/alternatives〉〈/inline-formula〉 and the second positive band system (〈inline-formula〉〈tex-math id="M9"〉\begin{document}${{\rm{C}}^{{3}}}\Pi _{\rm{u}}^{{ + }} \to {{\rm{B}}^{{3}}}\Pi _{\rm{g}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M9.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M9.png"/〉〈/alternatives〉〈/inline-formula〉 transition) of 〈inline-formula〉〈tex-math id="M10"〉\begin{document}${{\rm{N}}_{{2}}}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M10.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M10.png"/〉〈/alternatives〉〈/inline-formula〉. Under the action of high-intensity femtosecond laser, 〈inline-formula〉〈tex-math id="M11"〉\begin{document}${{\rm{N}}_{{2}}}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M11.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M11.png"/〉〈/alternatives〉〈/inline-formula〉 can be directly photo-ionized into 〈inline-formula〉〈tex-math id="M12"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}{{(}}{{\rm{B}}^{{2}}}\Sigma _{\rm{u}}^{{ + }})$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M12.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M12.png"/〉〈/alternatives〉〈/inline-formula〉, which results in fluorescence emission of 〈inline-formula〉〈tex-math id="M13"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M13.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M13.png"/〉〈/alternatives〉〈/inline-formula〉. In the process of femtosecond laser filament formation, the dynamic processes such as ionization and excitation of nitrogen molecules are affected by the laser intensity distribution and laser polarization direction. The products show different distributions in the propagation direction and radial space, which, in turn, affects its light emission. Therefore, it is necessary to further ascertain its generation mechanism through the spatial distribution of nitrogen fluorescence. In this experiment, the spatial distribution of the nitrogen fluorescence emission generated by linearly polarized femtosecond laser pulse filaments in air is measured. By changing the polarization direction of the laser to study the distribution of nitrogen fluorescence in the radial plane, it is found that the fluorescence emission of 〈inline-formula〉〈tex-math id="M14"〉\begin{document}${\rm{N}}_2^ + $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M14.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M14.png"/〉〈/alternatives〉〈/inline-formula〉 is more intense in the direction perpendicular to the laser polarization, while it is weaker in the direction parallel to the laser polarization. The nitrogen fluorescence emission has the same intensity in all directions. The ionization probability of a linear molecule depends on the angle between the laser polarization direction and the molecular axis, which is maximum (minimum) when the angle is 〈inline-formula〉〈tex-math id="M15"〉\begin{document}${{{0}}^{\rm{o}}}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M15.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M15.png"/〉〈/alternatives〉〈/inline-formula〉(〈inline-formula〉〈tex-math id="M16"〉\begin{document}${{9}}{{{0}}^{\rm{o}}}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M16.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M16.png"/〉〈/alternatives〉〈/inline-formula〉). The 〈inline-formula〉〈tex-math id="M17"〉\begin{document}${{\rm{N}}_{{2}}}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M17.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M17.png"/〉〈/alternatives〉〈/inline-formula〉 gas is more likely to be ionized in the laser polarization direction, the nitrogen molecular ions 〈inline-formula〉〈tex-math id="M18"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M18.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M18.png"/〉〈/alternatives〉〈/inline-formula〉 and electrons are separated in the direction parallel to the laser polarization. Therefore, more ions (〈inline-formula〉〈tex-math id="M19"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M19.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M19.png"/〉〈/alternatives〉〈/inline-formula〉) are generated in the direction parallel to the laser polarization, and the fluorescence emission of 〈inline-formula〉〈tex-math id="M20"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M20.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M20.png"/〉〈/alternatives〉〈/inline-formula〉 is more intense. Along the propagation direction of the laser, it is found that the fluorescence of 〈inline-formula〉〈tex-math id="M21"〉\begin{document}${{\rm{N}}_{{2}}}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M21.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M21.png"/〉〈/alternatives〉〈/inline-formula〉 appears before the fluorescence of 〈inline-formula〉〈tex-math id="M22"〉\begin{document}${\rm{N}}_2^ + $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M22.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M22.png"/〉〈/alternatives〉〈/inline-formula〉 and disappears after the fluorescence of 〈inline-formula〉〈tex-math id="M23"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M23.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M23.png"/〉〈/alternatives〉〈/inline-formula〉 has vanished. This is due to the fact that 〈inline-formula〉〈tex-math id="M24"〉\begin{document}${{\rm{N}}_{{2}}}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M24.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M24.png"/〉〈/alternatives〉〈/inline-formula〉 can be ionized into 〈inline-formula〉〈tex-math id="M25"〉\begin{document}${\rm{N}}_{{2}}^{{ + }}{{(}}{{\rm{B}}^{{2}}}\Sigma_{\rm{u}}^{{ + }})$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M25.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M25.png"/〉〈/alternatives〉〈/inline-formula〉 at the position of high enough laser intensity, thus emitting fluorescence of 〈inline-formula〉〈tex-math id="M26"〉\begin{document}${\rm{N}}_2^ + $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M26.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M26.png"/〉〈/alternatives〉〈/inline-formula〉. However, the laser energy is not enough to ionize nitrogen at the beginning and end of laser transmission, but it can generate 〈inline-formula〉〈tex-math id="M27"〉\begin{document}${\rm{N}}_2^ * $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M27.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M27.png"/〉〈/alternatives〉〈/inline-formula〉, which emits nitrogen fluorescence through the process of intersystem crossing 〈inline-formula〉〈tex-math id="M28"〉\begin{document}${\rm{N}}_2^*\xrightarrow{{{\rm{ISC}}}}{{\rm{N}}_2}({{\rm{C}}^3}\Pi _{\rm{u}}^ + )$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M28.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M28.png"/〉〈/alternatives〉〈/inline-formula〉. The spatial distribution of nitrogen fluorescence emission during femtosecond laser filament formation shows that in the case of short focal length, the intersystem crossing scheme can explain the formation of 〈inline-formula〉〈tex-math id="M29"〉\begin{document}${{\rm{N}}_{{2}}}{{(}}{{\rm{C}}^{{3}}}\Pi _{\rm{u}}^{{ + }})$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M29.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20201704_M29.png"/〉〈/alternatives〉〈/inline-formula〉. This research is helpful in understanding the mechanism of nitrogen fluorescence emission.

Abstract: The polycrystalline perovskite-phase PT/PZT/PT ferroelectric thin film was prepared by sol-gel method. The domain and domain wall structures were investigated by scanning force microscopy. The out-of-plane polarization(OPP), in-plane polarization(IPP), the OPP amplitude and OPP phase images were obtained. The domain of the film has a complex structure with c-domain and deviated-c-domain the direction of which deviated from the surface normal of the film. The complex domain structure is related to the orientation of the crystal grains in the film. For the［111］oriented films, the 180° domain wall is formed when deviated-c-domains have reverse directions in OPP and IPP. The 90° domain wall is formed when the domains have the same direction in OPP and reverse directions in IPP, or when they have reverse directions in OPP and same direction in IPP.

Abstract: CoPt/Ag nanocomposite films were prepared by magnetron sputtering. The dependenc e of texture and magnetic properties on film thickness, bilayer thickness, Ag at omic fraction and annealing conditions is investigated. Films with thickness bel ow 20 nm are apt to form (001) orientation. The existence of the Ag in the film plays a dominant role in inducing the (001) texture of the film besiles suppress ing the growth of the CoPt grains during annealing. The Co40Pt43 Ag17 film after annealing at 600℃ exhibits a large perpendicul ar coercivity of HC=5.6×105 A/m, a large saturation magne tization of MS=0.65T and a squareness of s=0.95 of the hysteresis loo p.

Abstract: The cavity field spectrum of a cascade three-level atom interacting with a single-mode field in an ideal cavity is investigated. When the atom is in the upper level and the field is vacuum initially,the number of Rabi peaks changes according to 2→6→4→2→4 with the increase of R=g2/g1,and all Rabi peaks disappear for R1 Three-peak,five-peak or seven-peak structure appear for weak initial fields,and single resonance peak appears for a st rong field. When the atom is in the middle level initially,the cavity field spectrum is of a two-peak structure with R=1 as the spectrum of Jaynes-Cummings model.

Abstract: Three kinds of definitions of disentanglement of 3-particle systems are given. Three basic regulations of a 3-particle system pure-state disentanglement are completely analyzed. It is shown that there are some sets of 3-particle entangled states that can be disentangled into product states or 1-particle product and 2-particle separable states or fully separable states, but a universal disentangling machine into product states or 1-particle product and 2-particle separable states or fully separable states cannot exist.