With the rapid development of material science and industrial technology, the application of ultrasonic Lamb wave to the industrial nondestructive testing has received considerable attention due to its advantages of rapidness, high efficiency, high accuracy, and low cost. However, the multimode and dispersion problem of Lamb waves are still challenging. Multimode mixed Lamb wave signals are often ...
In this paper, a method of designing the frequency selective structure based on spoof surface plasmon polariton (SSPP) is proposed and demonstrated. According to the applications in different working bands, the designed frequency selective surface (FSS) and metallic fishbone structure array can be combined together to form a new frequency selective structure and satisfy the requirements for practi...
Sheared-beam imaging (SBI) is a non-traditional imaging technique in which utilized are three sheared coherent lasers for illumination, and detector array to receive the intensity of speckle pattern reflected from the target. Finally the image of target can be reconstructed by computer algorithm from the data collected before. The SBI has some advantages in high resolution imaging for long-distanc...
A kind of dual micro-holes-based in-fiber Fabry-Perot interferometer sensor is proposed in this paper. The theoretical model of the reflection spectrum of proposed sensor is established based on the interference among four light beams, where both the relationships of the spectrum intensity with the length of micro-hole, refractive index (RI) of medium in cavity, transmission loss and reflection lo...
Magnetohydrodynamic (MHD) equations are solved by using the CTU+CT (corner transport upwind + constrained transport) algorithm which guarantees the divergence-free constraint on the magnetic field. The interactions between shock wave and heavy or light triangular cylinder are investigated in detail in the cases with and without magnetic field. In the cases of hydrodynamic (B=0 T) and MHD (B=0.01 T...
Random source is important for the security of key distribution. In this paper, a novel secure key distribution scheme based on unidirectional injection of vertical cavity surface emitting laser (VCSEL) system is proposed. In the proposed scheme, a chaotic signal without time delay signature is generated by a VCSEL subject to unidirectional optical injection, which is regarded as a master laser. T...
The propagation of interface waves at the interface between a fluid-saturated porous medium and a fluid has been extensively investigated in the last three decades due to its various and wide applications in several fields including earthquake engineering and materials testing. Although the sea floor is usually covered with porous marine sediment, the previous interface wave theories are rarely us...
The wolter-1 X-ray focusing mirror can reflect grazing incidence X-ray to the focal plane, which plays an important role in the astronomical detection and other fields due to its good image detecting capability. A geometric model of the optical system is established for theoretically deriving the optical path equations which is useful in this glass based focusing mirror designing, all the design p...
Nuclear design and neutronic analysis of thermal neutron reactor need high reliable thermal neutron cross sections. Uranium mononitride (UN) is a candidate fuel material for advanced power reactor with its better thermodynamics and accident tolerance. However, in thermal neutron region, reliable thermal neutron scattering cross sections are lacked for UN, which is disadvantageous to reactor physic...
The ions with different incident energies transmitting through insulating nanocapillaries are studied in various configurations. For the low energy ions transmitting through nanocapillaries, Stolterfoht et al.[2002 Phys. Rev. Lett. 88 133201] have observed the guiding effect. Subsequent studies revealed that the self-organizing charge patches on the capillary wall inhibit charge exchange and the i...
On the basis of the stimulated Raman adiabatic passage technology, we study the conversion of ultracold atoms into diatomic molecules by using a square-shaped pulse field. By the method of adiabatic fidelity, we analyze the dynamical evolution process of the coherent population trapping state for the atom-molecule conversion system. We introduce two adiabatic fidelities to describe the efficiency ...
Halogenated alkanes destroy the ozone layer, and iodoethane is one of the important representative halogenated alkanes. Time-of-flight mass spectrometry and velocity map imaging technique are used for investigating the photoionization dissociation dynamics of iodoethane, induced by 800 nm femtosecond laser. The dissociation mechanisms of iodoethane are obtained and discussed by analyzing the veloc...
According to the optical Stark deceleration theory of using a stationary quasi-cw red-detuned optical lattice to slow and trap an arbitrary pulsed molecular beam, we propose a novel idea of using a modulated optical lattice instead of a stationary one to realize a multistage optical Stark deceleration. We analyze the motion of the decelerated molecules inside the optical decelerator, and study the...
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
A lightning discharge in a thundercloud usually starts with a locally breakdown process (preliminary breakdown) followed by a widely extending leader process. In the early 1960 s, from the view of fundamental electrostatics[Kasemir H W 1960 J. Geophys. Res. 65 1873] suggested that the lightning leader is initiated by an electrodeless discharge with a zero-net-charge conductive channel extending bi...
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
A method of using energy loss to reconstruct the density is presented with protons at intermediate and high energy for proton radiography, and the equation and condition of density reconstruction are given based on the Bethe-Bolch formula. For the intermediate and high energy proton radiography, the stopping power of material is changed slowly within a certain energy range, and the stopping power ...
Dry granular materials consist of a collection of macroscopic discrete particles interacting solely via contact forces. By changing the external conditions, the granular packing displays rich phenomena ranging from fluid-like properties to jamming glassy behavior and to aging observed when these grains are trapped in a frozen state. Once the grains contact liquid, the force between the liquid and ...
Each of the seismogenic locked segments in a well-defined seismic zone can accumulate high strain energy to bring about a major earthquake. Hence, better understanding the physical implication of self-organized criticality in the locked segment (rock) failure process is crucial to achieving insights into such issues as earthquake predictability and so on. We point out that there exist two critical...
SPECIAL TOPIC—Tenth anniversary of the discovery of iron-based high temperature superconductors
We perform an in-plane optical spectroscopy measurement on iron-based superconductor Li0.8Fe0.2ODFeSe single crystal. At room temperature, the low frequency optical conductivity shows an incoherent characteristic; the Drude component is absent. With temperature decreasing, the Drude component develops and narrows rapidly. A well-defined plasma edge is observed in reflectance spectrum at temperatur...
Since the discovery of iron-based superconductors in 2008, it has been a hot topic to research the pairing mechanism of superconductivity. Scanning tunneling microscopy (STM) can be used to detect the electronic information in nano-scale, hence, it is an important tool to do research on superconductivity. In recent 10 years, many valuable works have been carried out by STM in iron-based supercondu...
Like the superconductivities in other unconventional superconductors, high-temperature superconductivity in the iron pnictide often emerges after the static antiferromagnetic order has been suppressed, and is always accompanied by strong spin fluctuations. Therefore, understanding the magnetism and its origin could be an important premise for ascertaining the microscopic mechanism of iron-based su...
With high transition temperature Tc (~38 K), high upper critical field Hc2 ( 100 T), superior transport Jc (~106 A/cm2) and extremely small anisotropy (1.5-2.0), the 122-type iron-based superconductors show great promise in high-field applications such as next-generation high energy physics accelerator and high-field magnetic resonance imaging (MRI). Power-in-tube (PIT) method is widely adopted to...
The 112-type (Ca, RE)FeAs2 (RE=rare earth) superconductors are very special among the iron-based superconductors for their particular crystal structures with arsenic chain configuration and attractive electronic phase diagram with the coexistence of superconductivity and antiferromagnetism upon carrier doping, while the chemical phases are absent for the low doping level or undoped parent compound...
Among the iron-based superconductors, the structural simplest FeSe and its derived materials have received much attention in recent years due to the great tunability of the superconducting transition temperature (Tc). The relatively low Tc 8.5 K of FeSe can be raised to over 40 K via the interlayer intercalations such as AxFe2-ySe2 (A=K, Rb, Cs, Tl), Lix(NH3)yFe2Se2, and (Li1-xFex)OHFeSe. Althoug...
The key structural unit of iron-based superconductors (FeSCs) is the Fe2X2 (X refers to a pnictogen or a chalcogen element) layer which stacks alternately along the crystallographic c axis with other spacer layers. This structural feature makes it possible to find FeSCs via rational material design. In this paper, we first review the crystal structure of FeSCs along with the relevant progress. The...
Since the high-Tc superconductivity in iron-based superconductors was found in 2008, numerous new iron-based superconductors have been discovered. Of them, FeSe-based superconductors receive the most attention due to their unique properties. Here, we briefly introduce the structure and physical properties of two newly found FeSe-based superconductors, i.e. (Li, Fe) OHFeSe and (CTA)x FeSe. The form...
The discovery of Fe-based superconductor in 2018 opened an illustrious chapter in the history of high temperature superconductors. Over the past ten years, many progresses on experiments, theories and applications have been achieved in the studies of Fe-based superconductors, which have greatly enriched the basic knowledge on the superconductivity of high temperature (Tc) superconductors and laid ...
Since the discovery of high-temperature superconductivity in cuprates, finding more unconventional superconductors and understanding their superconducting pairing mechanism has been an important theme in condensed matter physics. Recently, ternary Cr-based superconductors A2Cr3As3 (A=K, Rb, Cs) and ACr3As3 (A=K, Rb) were reported, which own quasi-one-dimensional crystal structure, containing[(Cr3A...
FeSe-based superconductors, as an important part of the family of iron-based superconducting materials, have attracted intensive research interest in the field of condensed matter physics. The exploration and preparation of such superconducting materials is the basis for studying their physical properties. At present, the exploration of FeSe-based superconducting materials mainly focuses on interc...
Copper oxide superconductors and iron-based superconductors are two important families of high temperature superconductors. Their high-temperature superconductivity mechanism is a long-standing issue and still in hot debate in the field of condensed matter physics. The extensive and in-depth exploration of iron-based superconductors and their comparative study with copper oxide high-temperature su...
111-typed iron based superconductors have three members: LiFeAs, NaFeAs and LiFeP. The family of LiFeAs itself does not show any long range magnetic order but become superconductor without chemical doping. NaFeAs displays the separation of structural and magnetic transition, suitable to investigate the origin of the two transitions. LiFeP has been proved to be a nodal superconductor. The structure...
High-quality superconducting single crystals and thin films play an important role in the basic research and application of high-Tc superconductivity. In these two aspects, iron-based superconductors feature the merit of rich physical phenomena and high superconducting critical parameters (including the transition temperature Tc, the upper critical field Hc2 and the critical current density Jc). B...
Iron-based superconductors and topological quantum states have been two important research frontiers in condensed matter physics in recent years. It is a very significant question whether the nontrivial topological phenomena can occur in iron-based superconductors. In this paper, the basic characteristics of the electronic structure of iron-based superconducting are analyzed from three aspects:cry...
We report on the observation of a superconducting gap of about 14-15 meV, significantly enlarged compared with the value of 2.2 meV for bulk FeSe, in monolayer FeSe film interfaced with MgO epitaxial on SrTiO3(001) substrate by using the scanning tunneling microscopy. While the MgO exhibits the same work function as SrTiO3 substrate, the gap magnitude is in coincidence with that of surface K-doped...
The similarities between the Fe-based superconductors and cuprate superconductors imply a possible unified picture of high temperature superconductivity. However, various chemical doping effects in Fe-based superconductors can lead to qualitatively similar phase diagrams that show diverse and complicated details, which pose great challenges of establishing a unified picture. Studying how chemical ...
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
Epsilon-near-zero mode provides a new path for tailoring light-matter interactions on a nanoscale because of its unique characteristics and ability to be used in many scientific fields. Among these applications, broadband absorption has aroused the considerable interest in photonic research. In this paper, we first show that the surface plasmon resonance is excited by the metal disk array structur...
The study on the field dependence of magnetocaloric effect (MCE) is considered to be of fundamental and practical importance, since it not only guides us in understanding and optimizing the MCE, but also helps us estimate the MCE for higher magnetic field which is not available in some laboratories. The magnetic field (0H) dependence of magnetic entropy change (△SM) has been studied extensively in...
Of all iron-based superconductors, FeSe possesses the simplest structure whereas its superconducting critical temperature can be remarkably enhanced. Compared with bulk sample fabrication, the film preparation process is very precise and controllable. Although FeSe monolayer films exhibit a high Tc, they are unstable in air, and ex-situ measurements are very difficult. Therefore, the stable films ...
Piezoelectric functional materials have been extensively studied and employed in numerous devices. With the rapid development of modern industries, such as power plants, aerospace, automotive, renewable energy and material processing industries, the high temperature piezoelectric materials that can work in extreme environments are in great demand.Piezoelectric materials including piezoelectric sin...
Organic light-emitting diodes (OLEDs) possess a number of advantages such as low power consumption, light weight, wide color gamut, high response speed, and high contrast ratio. They have received widespread attention due to their tremendous commercial applications in the fields of full-color flat panel display and solid-state lighting. Although nearly 100% internal quantum efficiency of OLED has ...
Plasma, as a special state of matter, has an effect on its inner conductors. Practically in the plasma environment, the effect may induce surface to charge and discharge, and may degrade the performance of spacecraft. Therefore, this effect needs to be further studied in the electromagnetic compatibility. The energy in a conductors' system is a key factor of the effect, which can also be used to d...