Magnetic skyrmions are topologically protected nano-scale spin textures. They normally exist in chiral magnets and magnetic thin films with broken inversion symmetry. The size of skyrmion ranges from 1 nm to several hundred nanometers, depending on the material parameters. The spins of skyrmion wrap around the unit sphere exactly once, thus facilitating the unit topological charge of a skyrmion. D...Liu Yi-Zhou, Zang JiadongActa Physica Sinica.2018, 67(13): 131201.
Quantum communication utilizes the quantum state as information carrier. The transmission of quantum states is therefore a precondition for various quantum communication protocols. Photons play a central role in quantum communication since they are fast, cheap, easy to control and interact weakly with the environment. However, the widely used polarization degree of freedom of photons is vulnerable...
Magnetic skyrmions are topologically protected nano-scale spin textures. They normally exist in chiral magnets and magnetic thin films with broken inversion symmetry. The size of skyrmion ranges from 1 nm to several hundred nanometers, depending on the material parameters. The spins of skyrmion wrap around the unit sphere exactly once, thus facilitating the unit topological charge of a skyrmion. D...
Magnetic field measurement and imaging with nanometer resolution is a key tool in the study of magnetism. There have been several powerful techniques such as superconducting quantum interference device, hall sensor, electron microscopy, magnetic force microscopy and spin polarized scanning tunneling microscopy. However, they either have poor sensitivity or resolution, or need severe environment of...
According to density functional theory calculations, we elucidate the atomic and electronic structure of -(Zn, Cr)S(111) surface. The magnetic interaction between Cr atoms is via S atoms close to the Cr layer. This interaction is shown by the analysis of spin charge contour plot and partial density of states (DOS) of each atom. The DOSs of other S atoms are non magnetic and have no magnetic exchan...
Study of critical phenomena plays a key role in developing the theory of phase transition. In this article, we mainly review some new experimental results about the critical phenomena reported recently in the helimagentic ordering materials. These materials exhibit a kind of a vortex-like spin texture so-called skyrmion phase. The skyrmion phase has great potential applications in the new spin-bas...
Magnetic skyrmions were first observed in a bulk B20 chiral magnet where the unit cell of the crystal lacks inversion symmetry, i. e. it is noncentrosymmetric, due to the Dzyaloshinskii-Moriya interaction (DMI). The breaking of structural inversion symmetry can also be achieved artificially in extremely thin FM layers adjacent to heavy elements, to induce a nonzero DMI. Many skyrmion properties in...
Owing to the topologically protected properties, magnetic skyrmions possess high stability and small critical driving current, thus making them potentially applied to future racetrack memory devices. Skyrmions have been identified in several material systems. One large class contains the centrosymmetric materials, where skyrmions emerge as the competition between perpendicular magnetic anisotropy ...
In a magnetic system, the spin orbit coupling can combine with the exchange interaction to generate an anisotropic exchange interaction that favors a chiral arrangement of the magnetization. This is known as the Dzyaloshinskii-Moriya interaction (DMI). Contrary to the Heisenberg exchange interaction, which leads to collinear alignment of lattice spins, the form of DMI is therefore very often to ca...
Understanding the correlations between magnetic skyrmions and the microstructural characteristics of the crystals that host skyrmions is a key issue for fundamental research and practical applications of novel type of magnetic materials. Magnetic skyrmion has received great attention due to its non-trivial topological properties and stability. Here we focus on two important points:1) dimensional c...
Magnetic skyrmion is expected to function as an ideal information carrier for ultra-high density magnetic storage and logic functional device in the future due to its superior properties, such as topological protection, small size, and low driving current density for motion. In order to meet the basic requirements for writing and reading information in devices, one needs to be able to accurately g...
Recently, a novel two-dimensional spin structure with non-trivial topological properties, called magnetic skyrmion, has been found in many chiral magnets. In most cases, magnetic skyrmions assemble spontaneously and form a lattice structure, called magnetic skyrmion crystal (SkX). SkX, as a novel macroscopic magnetic phase, may interact with different types of external fields through the intrinsic...
Magnetic skyrmion, as a quasi-particle, with topologically protected property has received wide attention. In this article, We first review the existence conditions and transport characteristics of magnetic skyrmions theoretically, then view recent micromagnetic simulation researches on creation and controlling as well as the device design, which includes racetrack memories, spin transfer nano-osc...
Skyrmions, as a nontrivial topological magnetic structure, have the advantages of topological stability, small size and low driving electrical current, showing potential applications in spintronic memory device. There are several mechanisms for skyrmion formation in magnets. One major mechanism is, in chiral-lattice ferromagnets, the competition between the Dzyaloshinskii-Moriya and ferromagnetic ...
Nanoscle magnetic skyrmions are topologically protected vortex-like spin textures that have been regarded as a promising candidate for the transport of information in further spintronic applications based on the racetrack memory concept due to their nanoscale dimension, stable particle-like feature, and an ultralow threshold for current-driven motion. Recently, most of the skyrmions are observed i...
Microelectronic technologies have been developing rapidly in the past half-century following the famous Moore's Law. However, this tendency is beginning to break down due to the thermal effects induced by the leakage current and data traffic. Spintronics sheds light on eliminating this bottleneck by using the spin degree of electron, which attracts great attention from both the academia and indust...
Magnetic skyrmions are a topologically stable and particle-like chiral spin configuration. They are appealing because of their potential applications in racetrack memory and other spintronic devices. These applications are strongly dependent on the skyrmion motion in confined geometry. Therefore, it is important to study the moving behaviors of skyrmions in a nanotrack to make them have more pract...
Magnetic skyrmions possess topologically non-trivial particle-like nanoscale domain wall structures, which have reasonably good stability and unique dynamic properties and can be controlled by magnetic fields, electric fields, and electric currents. Therefore, magnetic skyrmions are expected to be used as novel information carriers in the next-generation high-density, low-energy-consumption, and n...
The concept of skyrmion is proposed by Tony Skyrme, a British particle physicist, to describe a state of particles as a topological soliton. Magnetic skyrmion is a novel spin structure with topological behavior, whose size is on a nanometer scale. The space between skyrmions is tunable from a few nanometers to micrometer. Magnetic skyrmion can be stable in a large temperature range, from lower tem...
Magnetic skyrmions are topologically stable spin configurations with small size, which can be driven into motion by a small current. They are widely regarded as building blocks for next-generation magnetic storage. The main advantage of skyrmions lies in their particular dynamic behaviors, especially in their ability to move stably in racetrack under the action of small spin-polarized currents. Th...
Cu-Zr alloy system,as a representative of transition metal-transition metal (TM-TM) metallic glass (MG),has attracted considerable attention due to its high glass-forming ability in a wide range of compositions.Many researchers have realized that the GFA of Cu-Zr alloy is intimately related to Cu-centered Cu-Zr icosahedral atomic cluster in supercooled liquid and rapidly solidified into amorphous ...
In this paper, we use the quantum field theory to solve the generation process of particle-anti-particle pairs (PAPs), and study the generation characteristics of PAPs by changing the profile of the field combining an oscillating field and a static electric field. We find a way to increase the generation of PAPs and change the energy distribution. As the field strength of the oscillating field inc...
ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
Michelson interferometer can be applied to not only the building block of the fundamental research of physics, but also the precise measurement, such as the direct observation of gravity wave signal. Therefore, high performance Michelson interferometer is the key step towards the implementation of direct observation of weak gravity wave signal. Recently, the vacuum noise was reduced by injecting s...
Bessel beam is an important member of the family of non-diffracting beams and has some unique properties which can be used in many areas, such as micro particle manipulating, material processing and optical communication. However, the source of Bessel beam generated by the existing methods can be used only in a short distance due to its low power. In this paper, according to the coherent combining...
In particle sizing with dynamic light scattering (DLS) technique, the determination of particle size distribution (PSD), via inversing the autocorrelation function (ACF) of scattering light, is usually limited by the inherently low particle size information in ACF data and, the lack of targeted inversion on the noise restriction and the particle size information utilization. For the ACF data in DL...
Large-amplitude self-excited thermoacoustic oscillations arising due to the interaction between unsteady heat release and acoustic pressure fluctuations have been encountered in many thermal devices. These oscillations may lead to unwanted structural vibrations and efficiency reduction while emitting loud noises, and thus the predicting of such oscillations is very important. Physically, oscillati...
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
Since the moon has an extremely rarefied atmosphere, the full spectrum of the electromagnetic radiation of the sun reaches the surface, charging the surface dust and affecting its current charge state. Lunar surface dust thus remains electrostatically charged at all times. Charged lunar dust will adversely affect the operations of most mechanical systems required by manned and unmanned exploration...
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
In this paper a promising method of recognizing spatial contact state between carbon nanotubes (CNTs) and atomic force microscope (AFM) probe inside scanning electron microscope (SEM) is proposed. The CNTs can be picked up simply and effectively by van der Waals force without knowing depth information of SEM images by using this method. And a micro-nanorobotic manipulation system with 16 DOFs, whi...
Using first-principles calculations based on density functional theory, we investigate the electronic structures and optical properties of germanium doped by phosphorus and bismuth with different concentrations. By analyzing the electronic structures and optical properties of the doped systems, we can theoretically analyze and predict the optical and electrical practical applications of N-doped ge...
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
The optical tweezers with the special advantages of non-mechanical contact and the accurate measurement of positions of particles, are a powerful manipulating tool in numerous applications such as in colloidal physics and life science. However, the standard optical tweezers system uses a single objective lens for both trapping and imaging. As a result, the trapping and imaging regions are confined...
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
Owing to high critical temperature (125 K) and high upper critical field, TlBa2Ca2Cu3O9 (Tl-1223) superconductor is a kind of superconducting power transmission material working at liquefied natural gas temperature, and it has a great potential application value in the strong and weak electric field. In this work, the Tl-1223 superconducting films are fabricated by rapidly heating-up sintering tec...