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In recent years, there have been significant advances in the study of atomic gases with spinorbit coupling. Among these, a newly implemented type of spin-orbit coupling, known as spin-orbit angular momentum coupling, has drawn considerable interest due to its unique properties. In this article, we take fermionic gases as an example to introduce the implementation and characteristics of spin-orbit angular momentum coupling, emphasizing its important influence on single-particle spectra and particularly on fermionic superfluidity. By combining mean-field analytical methods and numerical simulations, we analyze the finite angular momentum pairing induced by spin-orbit angular momentum coupling and the resulting ground states of different types of superfluid vortices. Furthermore, we discuss relevant progress and potential future directions. [ABSTRACT FROM AUTHOR]

Dynamic susceptibility of thin truncated conical permalloy nanodisk with height 20 nm is simulated using micromagnetic simulations. Starting from a relaxed magnetic vortex state, the effect of tapering on the resonant modes is analyzed by changing the bottom radius (R = 50 nmto 100 nm) and top radius (r = 10 nmtoR − 10 nm) of the conical nanodisk. When an in-plane excitation field pulse is applied, the lowest resonant peak frequency increases with increase in r. This mode is originated due to vortex core translation and the variation of the resonant peak with r is well explained using Thiele's equation. Other resonant modes appear at higher excitation frequencies which are identified as azimuthal modes. When an out-of-plane excitation field is applied, all the spin wave modes appear to be axially symmetric. Appearance of new resonant modes and shifting of the resonant frequency is recorded by changing either of the parameter r or R for both the excitation field directions. The spatial distribution of FFT of magnetization at each resonant mode links the area of nanodisk that has maximum contribution to each mode and combining this with average center of magnetization perturbation, shifting of resonance frequency is explained successfully. The findings from this study prove that tunable resonant frequency can be achieved by tapering of truncated conical nanodisks. [ABSTRACT FROM AUTHOR]

The manipulation of charge and lattice degrees of freedom in atomically precise, low-dimensional ferroelectric superlattices can lead to exotic polar structures, such as a vortex state. The role of interfaces in the evolution of the vortex state in these superlattices (and the associated electrostatic and elastic boundary conditions they produce) has remained unclear. Here, the toroidal state, arranged in arrays of alternating clockwise/counterclockwise polar vortices, in a confined SrTiO3 /PbTiO3 /SrTiO3 trilayer is investigated. By utilizing a combination of transmission electron microscopy, synchrotron-based X-ray diffraction, and phase-field modeling, the phase transition as a function of layer thickness (number of unit cells) demonstrates how the vortex state emerges from the ferroelectric state by varying the thickness of the confined PbTiO3 layer. Intriguingly, the vortex state arises at head-to-head domain boundaries in ferroelectric a1 /a2 twin structures. In turn, by varying the total number of PbTiO3 layers (moving from trilayer to superlattices), it is possible to manipulate the long-range interactions among multiple confined PbTiO3 layers to stabilize the vortex state. This work provides a new understanding of how the different energies work together to produce this exciting new state of matter and can contribute to the design of novel states and potential memory applications.

In the present work, we will study the superconducting properties of a mesoscopic three-dimensional prism with square transversal section under an external magnetic field in both Zero-Field Cooling (ZFC) and Field-Cooling (FC) process. The studied sample is a three-band system (with three condensates ψ 1 , ψ 2 , ψ 3 ), in which we take a Josephson type inter-band coupling simulated via γ parameter. We analyze the magnetization, superconducting electronic density and free Gibbs energy considering both processes. As results, we found an interesting tunneling of vortex and anti-vortex between the bands, and vortex cluster configuration in the sample. This behaviour is due to the non-monotonic interaction between the bands. [ABSTRACT FROM AUTHOR]

Cylindrical nanodisks typically exhibit in-plane magnetization reversal comprising of nucleation and propagation of a vortex closure state. Present work investigates the magnetization reversal process in a cylindrical disk of radius ranging from 20 nm to 100 nm in which the flat surfaces at top and bottom are modified to convex shaped surfaces. It is found that the nucleation of vortex state no longer occurs as a result of this surface modification. Instead, a buckled magnetization state is nucleated which transforms to reverse buckled state yielding a square hysteresis loop. However, the out-of-plane hysteresis loop exhibits a vortex state at remanence. Analytical calculation of total free energy of both vortex as well as buckled state and the comparison thereof shows that the vortex state is ground state if radius of nanodisk is above 60 nm. Below this critical radius, buckled state is the ground state. But the non-appearance of vortex state at remanence in in-plane hysteresis loop of all of the nanodisks indicates a presence of energy barrier between vortex and buckled state. Height of the energy barrier is estimated using nudged elastic band method (NEBM) in all cases which proves that the energy barrier for vortex state weakens and the barrier for buckled state intensifies with the reduction of nanodisk size. At the critical radius of 60 nm , crossover of the two barrier heights occurs. Eventually, at the radius of 30 nm , the vortex state becomes totally unstable which can be toppled to buckled state with the slightest of perturbation. • In-plane hysteresis in convex nanodisk yields buckled state at remanence. • Remanent state is a vortex state for out-of-plane magnetization reversal. • Height of vortex to buckle state energy barrier decreases with radius. • Critical radius is 60 nm above which vortex is a stable state. [ABSTRACT FROM AUTHOR]

Our study sample is a superconducting bi-dimensional octagon with different boundary conditions immersed in a magnetic external field H. The boundary conditions are simulated by considering different values of the de Gennes extrapolation length b on different surfaces of the sample. Our investigation was carried out by solving the time-dependent Ginzburg–Landau equations. We analyzed the superconducting electron density and the magnetization curves as functions of H and temperature T in field-cooling and in zero-field-cooling processes for different values of b and size of the sample. We found a strong dependence of the critical fields on b and size of the sample. [ABSTRACT FROM AUTHOR]

In the present work, we studied the magnetization, vorticity, Cooper pairs density, and the spatial distribution of the local magnetic field in a three-dimensional superconductor with a SQUID geometry (a square with a central hole connected to the outside vacuum through a very thin slit). Our investigation was carried out in both the Meissner-Ochsenfeld and the Abrikosov state solving the two-band Ginzburg-Landau equations considering a Josephson coupling between the bands. We found a non-monotonic vortex behavior and the respective generation of vortex clusters due to the Josephson coupling used between condensates. [ABSTRACT FROM AUTHOR]

Magnetic nanodots are of high interest for basic research due to their broad spectrum of possible magnetic states and magnetization reversal processes. Besides, they are of technological interest since they can be applied in magnetic data storage, especially if vortex states occur in closed dots or open rings. While producing such nanorings and nanodots from diverse magnetic materials by lithographic techniques is quite common nowadays, these production technologies are naturally prone to small deviations of the borders of these nanoparticles. Here we investigate the influence of well-defined angular-dependent roughness of the edges, created by building the nanoparticles from small cubes, on the resulting hysteresis loops and magnetization reversal processes in five different round nanodots with varying open areas, from a thin ring to a closed nanodot. By varying the orientation of the external magnetic field, the impact of the angle-dependent roughness can be estimated. Especially for the thinnest ring, significant dependence of the transverse magnetization component on the field orientation can be found. [ABSTRACT FROM AUTHOR]

The vortex states in electron-doped high-Tc superconductors are studied theoretically at the mean-field approach and based on the Bogoliubov-de Gennes equations. The local density of states is calculated, through which the in-gap bound states are revealed. They are robust at the sites around the vortex core. In the underdoped region where the antiferromagnetic order and the superconducting order coexist, the in-gap peaks are lying symmetric with respect to the Fermi energy, while the peak intensities at the negative energy are much stronger. A stripe-type modulation is revealed for the spin-resolved local density of states. As the doping density increases to the optimal or over-doped region, the long-range antiferromagnetic order disappears, and the two in-gap peaks merge to one single peak. The peak position is near the Fermi energy. Our results indicate that the vortex states may be used to detect the signature of the antiferromagnetic order in electron-doped high-Tc superconductors. [ABSTRACT FROM AUTHOR]

We studied the (magnetic field-temperature) phase diagram, the resistive state, and the vortex configurations of a rectangular superconducting loop, under an electrical transport current J, and an external applied magnetic field H. We show that the critical current density in the I − V characteristic curve Jc1, at which the first vortex–antivortex (V-Av) pair nucleates in the sample, as well as the number of jumps in the I − V curve (i.e., different resistive states), strongly depends on the temperature of the sample and the spatial variation of critical temperature in the sample. [ABSTRACT FROM AUTHOR]

We analyzed the role of the inclusion of anti-dots on the vortex state and some calorimetric properties of a mesoscopic superconducting square immersed in an external applied magnetic field. We calculated the magnetization, entropy, Gibbs free energy, density of Cooper pairs and specific heat for this system in a zero field cooling process, solving the time-dependent Ginzburg–Landau equations. We found that the critical temperature is non-dependent on the number of anti-dots and dependent slightly on the size of the defects. Oscillations in the entropy and specific heat are found due the temperature dependence of the superconducting characteristics length. [ABSTRACT FROM AUTHOR]

Ordered ferromagnetic nanowire arrays are widely studied due to the diversity of possible applications. However, there is still no complete understanding of the relation between the array's parameters and its magnetic behavior. The effect of vortex states on the magnetization reversal of large-diameter nanowires is of particular interest. Here, we compare analytical and micromagnetic models with experimental results for three arrays of iron nanowires with diameters of 33, 52 and 70 nm in order to find the balance between the number of approximations and resources used for the calculations. The influence of the vortex states and the effect of interwire interactions on the remagnetization curves are discussed. It has been found that 7 nanowires treated by a mean field model are able to reproduce well the reversal behavior of the whole array in the case of large diameter nanowires. Vortex states tend to decrease the influence of the structural inhomogeneities on reversal process and thus lead to the increased predictability of the system. [ABSTRACT FROM AUTHOR]

We studied the influences of the inclusion of different geometrical defects (circle, triangle, and square) with different Ginzburg–Landau parameters κ on the vortex state of a mesoscopic superconducting square immersed in an external applied magnetic field. We calculated the magnetization, vorticity, and density of Cooper pairs for this system, solving the time-dependent Ginzburg–Landau equations. We found a novel and interesting behavior of the vorticity (N < 0) at low magnetic fields: a spontaneous generation of anti-vortices due to the breaking inversion symmetry. [ABSTRACT FROM AUTHOR]

Particles in vortex states have gained arising interests due to the additional degree of freedom—the orbital angular momentum (OAM) inherently existing in the state. With the increasing energy of vortex particles (photons, leptons etc), the research has gradually transitioned from the classical field regime to collisions of vortex particles in the quantum-field regime. The latter provides a new way to study the rich properties of particle physics. Here, we show the characteristics of vortex states in bremsstrahlung by deriving the corresponding scattering probability following the quantum-electrodynamics theory. The theory allows us to obtain the OAM distribution of the outgoing vortex photon and the law of OAM transfer during interaction. It is shown that the generated photon takes most of the initial electron OAM, especially when the latter is more energetic. The opening angle of outgoing particles in vortex bremsstrahlung is also significantly different from plane wave scattering. The effects of polarization and non-zero impact parameter are also discussed. The results illustrate the unique feature of vortex scattering and suggest a feasible way to generate high-energy vortex photons—a novel source in studying nuclear physics.

Magnetic enhancement of Chinese loess‐paleosol sequences has been used extensively as a proxy for East Asian summer monsoon variations. However, the pedogenic magnetic particles contributing to this magnetic enhancement are difficult to extract, so it is not clear how they formed. In this study, we reveal pedogenic magnetite and hematite using electron microscopy, synchrotron radiation X‐ray diffraction, and rock magnetic methods. First‐order reversal curves indicate that superparamagnetic/single domain/vortex state magnetic properties dominated both loess and paleosol samples. Samples of muscovite and chlorite, which are paramagnetic, have weak spontaneous magnetization. The 1‐ to 10‐μm‐sized fraction of host silicatesis responsible for most of the magnetic enhancement of paleosols. In the paleosol fraction, we found weathered phyllosilicates (muscovite/chlorite), including many elongated submicron to a few microns authigenic magnetite and hematite particles between layers; however, few such interlayer particles were found in phyllosilicates of the loess fraction. The concentration of magnetite/hematite particles within paleosol muscovite/chlorite grains and in aggregates of phyllosilicate fragments is much higher than that of the submicron iron oxides found on silicate surfaces. Interlayer magnetite particles are dominantly prism‐shaped with aspect ratios >~4. The authigenic magnetite must be mainly responsible for the spontaneous magnetization of the muscovites and chlorites and the paleosol magnetic properties. The protective silicates account for the low extraction efficiency and also the near absence of surface oxidation of pedogenic magnetite. Based on our results, we suggest that magnetite/hematite in weathered phyllosilicates contribute significantly to the magnetic enhancement of mature paleosols. Key Points: Hundreds of nanometer‐micron‐sized authigenic magnetite/hematite particles are highly concentrated in paleosol muscovite/chlorite grainsThe authigenic iron oxides are mainly responsible for the weak spontaneous magnetization of weathered muscovite and chlorite grainsElongated authigenic magnetites account for the dominant single domain/vortex state magnetic property and magnetic enhancement in paleosols [ABSTRACT FROM AUTHOR]

Magnetic configurations in heterostructures are often difficult to probe when the magnetic entities are buried inside. In this study we have captured magnetic and magnetoresistance "fingerprints" of Co nanodiscs embedded in Co/Cu multilayered nanowires using a first-order reversal curve method. In 200nm diameter nanowires, the magnetic configurations can be tuned by adjusting the Co nanodisc aspect ratio. Nanowires with the thinnest Co nanodiscs exhibit single domain behavior, while those with thicker Co reverse via vortex states. A superposition of giant and anisotropic magnetoresistance is observed, which corresponds to the different magnetic configurations of the Co nanodiscs.

• Temperature effect on minor loop parameters and magenetostatic interactions on Fe 70 Ga 30 thin film. • Increase in grain size leads to decrease in energy loss coefficient W F 0 and trough depth coefficient W R 0. • Evidence for the coexistence of multidomain and Vortex State (VS) in all the FeGa thin films from FORC. We report on the temperature evolution of pseudo magnetic properties and vortex state in Fe 71 Ga 29 thin films at different substrate temperatures (RT-25 °C, 50 °C, 75 °C, and 150 °C) using minor loop analysis and first-order reversal curves respectively. Phase purity of Fe 71 Ga 29 thin films confirmed with grazing incidence X–ray diffraction, which confirms the A2-type disordered phase. The minor loop parameters such as energy loss coefficient W F 0 (362 kOe.emu/cc to 278 kOe.emu/cc) and trough depth coefficient W R 0 (67.30 kOe.emu/cc to 50.23 kOe.emu/cc) values drop as grain size increases due to a reduction in defects as a result of an increase in substrate temperature. First-order reversal curves allow us to estimate the coercivity variation and switching field distribution that allow us to get information about magnetic interactions between the domains. Additionally, the contour plots of FORC and MFM phase images infer the coexistence of multidomain and Vortex State (VS) in all the Fe 71 Ga 29 thin films deposited at different substrate temperatures. [ABSTRACT FROM AUTHOR]

Magnetic nanodots are of high interest for basic research due to their broad spectrum of possible magnetic states and magnetization reversal processes. Besides, they are of technological interest since they can be applied in magnetic data storage, especially if vortex states occur in closed dots or open rings. While producing such nanorings and nanodots from diverse magnetic materials by lithographic techniques is quite common nowadays, these production technologies are naturally prone to small deviations of the borders of these nanoparticles. Here we investigate the influence of well-defined angular-dependent roughness of the edges, created by building the nanoparticles from small cubes, on the resulting hysteresis loops and magnetization reversal processes in five different round nanodots with varying open areas, from a thin ring to a closed nanodot. By varying the orientation of the external magnetic field, the impact of the angle-dependent roughness can be estimated. Especially for the thinnest ring, significant dependence of the transverse magnetization component on the field orientation can be found.

Highlights • In iron nanodots with a broad range of thicknesses and diameters, 8 different magnetization reversal mechanisms were found. • Stability of single and double vortex states depends strongly on the nanodot thickness and diameter. • For relatively thick nanodots (min. 20 nm), the single-vortex state was always found to be the ground state. Abstract Magnetic nanodots are of high technological importance in diverse storage and spintronics applications, especially in bit patterned media. Magnetization reversal in such nanodots typically occurs either by coherent rotation of the magnetization or along a vortex state. Other mechanisms of magnetization reversal are scarcely described in the literature. Understanding and predicting the magnetization reversal processes, however, is of utmost importance due to the varying stray fields in the different states under evolution, influencing neighboring nanodots in an array or matrix-like structure. Besides, the stability of vortex states against magnetic field changes – which corresponds to typically broad field ranges with reversible modifications of the magnetic state – influences the robustness of magnetically stored information as well as the necessary external fields for writing new information. Here we report on micromagnetic simulations on nanodots with 10 different, representative diameters and 10 dot thicknesses, respectively, giving rise to 8 possible magnetization reversal processes and suggesting the preconditions for the nucleation and propagation of one or two vortices in cylindrical iron disks. We show the impact of the dimensions and aspect ratios on all phases of magnetization reversal. This study results in a phase diagram of the different magnetization reversal processes. [ABSTRACT FROM AUTHOR]

Vortex patterns are determined for a three-dimensional mesoscopic superconductor with one central weak link, using the time-dependent Ginzburg-Landau equations. The vortex states are obtained for field orientation parallel and perpendicular to the weak link, and vortex rearrangements are found to occur in the vortex patterns. Tilting of the field leads to interesting phenomena caused by the small volume-to-surface ratio, as vortex tubes are preferentially oriented along the field direction while they are forced to be perpendicular to the surface. In addition, we can also observe the intersection of vortex tubes inside (or near) the weak link. [ABSTRACT FROM AUTHOR]

The spin valve principle is the most prominent sensor design among giant- (GMR) and tunneling (TMR) magnetoresistive sensors. A new sensor concept with a disk shaped free layer enables the formation of a flux-closed vortex magnetization state if a certain relation of thickness to diameter is given. The low frequency noise of current-in-plane GMR sensing elements with different free layer thicknesses at different external field strengths has been measured. The measurements of the 1/f noise in external fields enabled a separation of magnetic and electric noise contributions. It has been shown that while the sensitivity is increasing with a decreasing element thickness, the pink noise contribution is increasing too. Still the detection limit at low frequencies is better in thinner free layer elements due to the higher sensitivity.