Small Field Strengths Research Articles

Effect of the magnetic field on the conductance and spin polarization in phosphorene superlattice

The spin-dependent conductance and spin polarization are investigated theoretically in a phosphorene superlattice in the presence of external magnetic field and Rashba interaction. It is demonstrate that, the spin-dependent conductance with and without spin-flip as well as spin polarization can be effectively controlled by changing the magnetic field strength and the number of the superlattice barriers. For small magnetic field strength, the conductance for with and without spin-flip shows an oscillating behavior as increasing the strength of the Rashba interaction, and by increasing the number of barriers, the oscillating behavior becomes prominent. Further, when the magnetic field is greater than a limit value, the spin conductance will be zero. The size of the spin-dependent transmission window in the phosphorene superlattice under external magnetic field decreases drastically. The magnitude, sign and behavior of the spin polarization can be tuned by the amount of the external magnetic field.

Nanoparticle-laden droplet-liquid film electrocoalescence behaviors: A molecular dynamics simulation

Electrocoalescence is an efficient and environmentally friendly process for separating water-in-oil (W/O) emulsions. In this paper, molecular dynamics (MD) simulation method was used to study the electrocoalescence behaviors of nanoparticle-laden (NP-laden) droplet-liquid film. The results showed that the coalescence behaviors successively exhibited three modes, i.e., complete coalescence (CC) mode, critical state, and partial coalescence (PC) mode, with increasing direct current (DC) electric field strengths. The alternating current (AC) electric fields tended to promote the CC mode, and the coalescence efficiencies increased with increasing frequencies. Compared with the pure water droplet, the NP-laden droplets had greater tendencies to exhibit PC mode. In addition, the droplet with large We numbers produced strong impact force, and thus promoted rapid coalescence process. In the two-droplets system, due to the large number of water (H2O) molecules, droplet polarization phenomena were much significant under electric fields, hence resulting in PC mode at small field strengths. It is noteworthy that, at the absence of electric fields, the huge initial kinetic energy (EK) carried by the two droplets could overcome the surface energy (ES) at small We, and thus the droplet was detached from the liquid film. This work can provide theoretical guidance for designing compact and efficient oil–water separators.

Stringent test of QED with hydrogen-like tin

Inner-shell electrons naturally sense the electric field close to the nucleus, which can reach extreme values beyond 1015 V cm−1 for the innermost electrons1. Especially in few-electron, highly charged ions, the interaction with the electromagnetic fields can be accurately calculated within quantum electrodynamics (QED), rendering these ions good candidates to test the validity of QED in strong fields. Consequently, their Lamb shifts were intensively studied in the past several decades2,3. Another approach is the measurement of gyromagnetic factors (g factors) in highly charged ions4–7. However, so far, either experimental accuracy or small field strength in low-Z ions5,6 limited the stringency of these QED tests. Here we report on our high-precision, high-field test of QED in hydrogen-like 118Sn49+. The highly charged ions were produced with the Heidelberg electron beam ion trap (EBIT)8 and injected into the ALPHATRAP Penning-trap setup9, in which the bound-electron g factor was measured with a precision of 0.5 parts per billion (ppb). For comparison, we present state-of-the-art theory calculations, which together test the underlying QED to about 0.012%, yielding a stringent test in the strong-field regime. With this measurement, we challenge the best tests by means of the Lamb shift and, with anticipated advances in the g-factor theory, surpass them by more than an order of magnitude.

Simultaneous direct measurement of the electrocaloric and dielectric dynamics of ferroelectrics with microsecond temporal resolution

A contactless technique for direct time-resolved measurements of the full dynamics of the adiabatic temperature change in electrocaloric materials is introduced. The infrared radiation emitted by the electrocaloric sample is sensitively detected with μs time resolution and mK temperature resolution. We present time-resolved measurements of the electrocaloric effect up to kHz frequencies of the driving electric field and down to small field strengths. The simultaneous recording of transients for applied electric field and induced polarization gives a comprehensive view of the correlation of electrocaloric and ferroelectric properties. The technique can further be applied to the continuous measurement of fatigue for >106 electric field cycles.

Dissipation of field-aligned currents in the topside ionosphere

Field-aligned currents (FACs) are electric currents parallel to the geomagnetic field and connecting the Earth’s magnetosphere to the high-latitude ionosphere. Part of the energy injected into the ionosphere by FACs is converted into kinetic energy of the surrounding plasma. Such a current dissipation is poorly investigated, mainly due to the high electrical conductivity and the small electric field strength expected in direction parallel to the geomagnetic field. However, previous results in literature have shown that parallel electric field is not null (and may be locally not negligible), and that parallel electrical conductivity is high but finite. Thus, dissipation of FACs may occur. In this work, for the first time, we show maps of power density dissipation features associated with FACs in the topside ionosphere of the Northern hemisphere. To this aim, we use a 6-year time series of data at one second cadence acquired by the European Space Agency’s “Swarm A” satellite flying at an altitude of about 460 km. In particular, we use data from the Langmuir probe together with the FAC product provided by the Swarm team. The results obtained point out that dissipation of FACs, even if small when compared to that associated with horizontal currents flowing about 350 km lower, is not null and shows evident features co-located with electron temperature at the same altitude. In particular, power density dissipation features are enhanced mainly in the ionospheric regions where intense energy injection from the magnetosphere occurs. In addition, these features depend on geomagnetic activity, which quantifies the response of the Earth’s environment to energetic forcing from magnetized plasma of solar origin.

Radio detection of chemically peculiar stars with LOFAR

Context. Chemically peculiar stars are upper main sequence stars that show anomalies in their optical spectra. These anomalies suggest peculiar chemical abundances of certain elements. Some chemically peculiar stars possess strong magnetic fields. Electrons originating from the ionising stellar wind travel in the magnetosphere of the star and become the source of non-thermal radio and X-ray emission. Several chemically peculiar radio stars have been detected at GHz frequencies. Aims. We used the Low-Frequency Array (LOFAR) to search for radio emission from chemically peculiar stars to constrain their emission in the frequency band 120–168 MHz. We aimed to use LOFAR observations to test the models for radio emission of chemically peculiar stars. Methods. We performed a targeted search of known chemically peculiar stars in the fields of the LOFAR Two Metre Survey (LoTSS) Data Release 2 in Stokes I and V. We matched positions of radio sources in the LoTSS-DR2 catalogue with positions of chemically peculiar stars. Results. We report non-thermal emission at 120–168 MHz from two chemically peculiar stars in Stokes I, BP Boo, and α2 CVn. The ensuing incidence rate at these frequencies is significantly lower than for higher frequencies. This results from the turnover at low frequencies which was predicted from the theory of radio emission from chemically peculiar stars. BP Boo is detected for the first time at radio wavelengths, while α2 CVn had already been detected at higher frequencies. The upper limit of V/I indicates a level of circular polarisation significantly below 60%. We combined data obtained at different frequencies to derive the radio spectrum of α2 CVn. The spectrum is nearly flat beyond turnover at low frequencies. We modelled radio emission for a large magnetosphere and small local magnetic field strength. The amplitude of variation in radio emission with the rotational phase of the system decreases at low frequencies.

Magnetic Circuit Design and Experiment of Novel Lorentz Magnetic Bearing with Double Air Gap

A uniform magnetic density distribution in the air gap is key for the Lorentz magnetic bearing to achieve high precision control and large torque output. To overcome the small magnetic field strength in an explicit magnetic bearing and a high magnetic density fluctuation rate in an implicit Lorentz magnetic bearing, a second air gap design method is proposed based on the maximum magnetic density distribution in the winding area. A novel Lorentz bearing with a double second air gap is designed. The maximum magnetic field strength in the winding area is calculated by the finite element method, and the structure of the double second air gap is designed. To reduce the calculation error of the magnetic field strength, the division of the reluctance by the magnetic induction line is proposed. The reluctance calculation formula is given. Based on Ohm’s law, the calculation of the magnetic field strength is obtained. Finally, a prototype of the novel Lorentz magnetic bearing is made. The magnetic field strength in the winding area and the magnetic density fluctuation rate are measured with a magnetic density measurement instrument. The maximum magnetic flux density in the winding area is 0.631 T, and the magnetic field strength is 0.58%. Less difference is found between the measurement result and the finite element result.

Deep learning inversion of gravity data for detection of CO2 plumes in overlying aquifers

We developed an effective U-Net based deep learning (DL) model for inversion of surface gravity data on a rectangular grid to predict 2-D high-resolution subsurface CO2 distribution along a vertical cross-section due to CO2 leakage through a wellbore within a deep CO2 storage reservoir. We used synthetic data to model two types of CO2 leakage scenarios: one CO2 plume in a shallow aquifer (single plume case), and two plumes present at different depths (double plume case). The 3-D synthetic plume samples were created by sampling among predetermined CO2 plume depths, saturations, and volumes. The corresponding surface gravity data on a rectangular grid were generated by a 3-D forward model. The U-Net model detected 72% of single-plume samples, and one or both plumes in 75% of double-plume samples. Most of the undetected single plumes have small gravity field strengths below the typical noise level of 5 μGal. This model generated reproducible, reliable predictions with acceptable errors and demonstrated improved spatial resolution over the conventional least-squares inversion. In contrast to the conventional least-squares inversion, which often overestimates the size of its target and underestimates its density, this U-Net model accurately delineated the boundary of a target. Furthermore, this DL inversion detected deep, small, or low saturation CO2 plumes that are often more difficult to resolve with conventional gravity inversion methods. We note the limitations of this feasibility study, including the use of synthetic data with regular CO2 plume shapes, and the prediction of a 2-D plume cross-section rather than the full 3-D plume, as well, we recognize the lower detection fraction for double-plume scenarios. Nevertheless, this study demonstrates that DL gravity inversion is a promising and potentially superior method to conventional least-squares inversion. Our U-Net based deep learning inversion approach may be adapted for inversion of other types of geophysical data. DL inversion can facilitate near real-time monitoring of geologic carbon sequestration to provide site operators with prompt information about subsurface CO2 distribution for risk management and mitigation.

Electronic properties and tunable Schottky barrier of non-Janus MoSSe/graphene heterostructures

We investigate the stability and electronic properties of van der Waals junctions composed with graphene and non-Janus MoSSe in comparison with graphene/Janus MoSSe configuration, and furthermore explore its Schottky barrier as well as the effect of external electric field. Based on first-principles calculations, we compare the interlayer distance and binding energy between them. It is found that with the adhesion of graphene, the less-stable Janus MoSSe becomes the most stable configuration. The graphene/non-Janus MoSSe configuration has the minimum interlayer distance, and the weak vdW interactions indicates the preservation of unique electronic properties in both two materials. An n-type Schottky contact with the Schottky barrier height (SBH) of 0.38 eV is formed at the equilibrium state for graphene/non-Janus MoSSe, while the n-type SBH for two configurations of graphene/Janus MoSSe is 0.67 and 0.10 eV, respectively. With the application of an external electric field perpendicularly to the surface, not only the Schottky barrier height but also the transition of n-type and p-type Schottky contacts as well as Ohmic contacts can be modulated within a relatively small electric field strength. This property distinguishes graphene/non-Janus MoSSe from graphene/Janus MoSSe configuration, and provides great potential for applications in optoelectronic and nanoelectronic and devices.

The Significance of Echo Time in fMRI BOLD Contrast: A Clinical Study during Motor and Visual Activation Tasks at 1.5 T.

Blood Oxygen Level Dependent (BOLD) is a commonly-used MR imaging technique in studying brain function. The BOLD signal can be strongly affected by specific sequence parameters, especially in small field strengths. Previous small-scale studies have investigated the effect of TE on BOLD contrast. This study evaluates the dependence of fMRI results on echo time (TE) during concurrent activation of the visual and motor cortex at 1.5 T in a larger sample of 21 healthy volunteers. The experiment was repeated using two different TE values (50 and 70 ms) in counterbalanced order. Furthermore, T2* measurements of the gray matter were performed. Results indicated that both peak beta value and number of voxels were significantly higher using TE = 70 than TE = 50 ms in primary motor, primary somatosensory and supplementary motor cortices (p < 0.007). In addition, the amplitude of activation in visual cortices and the dorsal premotor area was also higher using TE = 70 ms (p < 0.001). Gray matter T2* of the corresponding areas did not vary significantly. In conclusion, the optimal TE value (among the two studied) for visual and motor activity is 70 ms affecting both the amplitude and extent of regional hemodynamic activation.

New ex-OH maser detections in the northern celestial hemisphere

Aims.Molecular masers, including methanol and hydroxyl masers, and in particular the ones in excited rotational states (ex-OH masers), are one of the most informative tools for studying star-forming regions. So, the discovery, of new maser sources in these regions is of great importance. Many studies and surveys of ex-OH maser sources have been carried out in the southern celestial hemisphere, but only a few have been done in the northern hemisphere. The specific aim of this work is to close this gap.Methods.The star-forming regions in the northern hemisphere with known active methanol masers were observed to search for new ex-OH maser sources with the 32 m and 16 m radio telescopes of the Ventspils International Radio Astronomy Centre (VIRAC).Results.Three OH maser lines in the excited state at the 6035 MHz in three northern hemisphere star-forming regions are detected. The maser 189.030+0.783 was previously known, but we suggest this maser is a possible variable. We confirm recent detections of the ex-OH masers 85.41+0.00 and 90.92+1.49 by other authors. The magnetic field strength in the masering regions is estimated by using right circular polarization and left circular polarization pair splitting. The high-velocity resolution provides us with an estimation of a comparatively small magnetic field strength for the 189.030+0.783 and 90.92+1.49 star-forming regions.

QCD phase diagram in a magnetized medium from the chiral symmetry perspective: the linear sigma model with quarks and the Nambu–Jona-Lasinio model effective descriptions

We review the main features of the QCD phase diagram description, at finite temperature, baryon density and in the presence of a magnetic field, from the point of view of effective models, whose main ingredient is chiral symmetry. We concentrate our attention on two of these models: The linear sigma model with quarks and the Nambu--Jona-Lasinio model. We show that a main ingredient to understand the characteristics of the phase transitions is the inclusion of plasma screening effects that capture the physics of collective, long-wave modes, and thus describe a prime property of plasmas near transition lines, namely, long distance correlations. Inclusion of plasma screening makes possible to understand the inverse magnetic catalysis phenomenon even without the need to consider magnetic field-dependent coupling constants. Screening is also responsible for the emergence of a critical end point in the phase diagram even for small magnetic field strengths. Although versatile, the NJL model is also a more limited approach since, being a non-renormalizable model, a clear separation between pure vacuum and medium effects is not always possible. The model cannot describe inverse magnetic catalysis unless a magnetic field dependent coupling is included. The location of the critical end point strongly depends on the choice of the type of interaction and on the magnetic field dependence of the corresponding coupling. Overall, both models provide sensible tools to explore the properties of magnetized, strongly interacting matter. However, a cross talk among them as well as a consistent physical approach to determine the model parameters is much needed.

Structures and Dissolution Behaviors of Quaternary CaO-SrO-P2O5-TiO2 Glasses.

Calcium phosphate glasses have a high potential for use as biomaterials because their composition is similar to that of the mineral phase of bone. Phosphate glasses can dissolve completely in aqueous solution and can contain various elements owing to their acidity. Thus, the glass can be a candidate for therapeutic ion carriers. Recently, we focused on the effect of strontium ions for bone formation, which exhibited dual effects of stimulating bone formation and inhibiting bone resorption. However, large amounts of strontium ions may induce a cytotoxic effect, and there is a need to control their releasing amount. This work reports fundamental data for designing quaternary CaO-SrO-P2O5-TiO2 glasses with pyro- and meta-phosphate compositions to control strontium ion-releasing behavior. The glasses were prepared by substituting CaO by SrO using the melt-quenching method. The SrO/CaO mixed composition exhibited a mixed cation effect on the glassification degree and ion-releasing behavior, which showed non-linear properties with mixed cation compositions of the glasses. Sr2+ ions have smaller field strength than Ca2+ ions, and the glass network structure may be weakened by the substitution of CaO by SrO. However, glassification degree and chemical durability of pyro- and meta-phosphate glasses increased with substituted all CaO by SrO. This is because titanium groups in the glasses are closely related to their glass network structure by SrO substitution. The P-O-Ti bonds in pyrophosphate glass series and TiO4 tetrahedra in metaphosphate glass series increased with substitution by SrO. The titanium groups in the glasses were crosslink and/or coordinate phosphate groups to improve glassification degree and chemical durability. Sr2+ ion releasing amount of pyrophosphate glasses with >83% SrO substitution was larger than 0.1 mM at day seven, an amount that reported enhanced bone formation by stimulation of osteogenic markers.

Stokesian dynamics simulations of a magnetotactic bacterium

The swimming of bacteria provides insight into propulsion and steering under the conditions of low-Reynolds number hydrodynamics. Here we address the magnetically steered swimming of magnetotactic bacteria. We use Stokesian dynamics simulations to study the swimming of single-flagellated magnetotactic bacteria (MTB) in an external magnetic field. Our model MTB consists of a spherical cell body equipped with a magnetic dipole moment and a helical flagellum rotated by a rotary motor. The elasticity of the flagellum as well as magnetic and hydrodynamic interactions is taken into account in this model. We characterized how the swimming velocity is dependent on parameters of the model. We then studied the U-turn motion after a field reversal and found two regimes for weak and strong fields and, correspondingly, two characteristic time scales. In the two regimes, the U-turn time is dominated by the turning of the cell body and its magnetic moment or the turning of the flagellum, respectively. In the regime for weak fields, where turning is dominated by the magnetic relaxation, the U-turn time is approximately in agreement with a theoretical model based on torque balance. In the strong-field regime, strong deformations of the flagellum are observed. We further simulated the swimming of a bacterium with a magnetic moment that is inclined relative to the flagellar axis. This scenario leads to intriguing double helical trajectories that we characterize as functions of the magnetic moment inclination and the magnetic field. For small inclination angles (lesssim {20^{circ }}) and typical field strengths, the inclination of the magnetic moment has only a minor effect on the swimming of MTB in an external magnetic field. Large inclination angles result in a strong reduction in the velocity in direction of the magnetic field, consistent with recent observations that bacteria with large inclination angles use a different propulsion mechanism.Graphic abstract

Dielectric and thermal properties of aluminoborosilicate glasses doped with mixed rare-earth oxides

This study discusses aluminoborosilicate glasses with La2O3 and CeO2. Structural, thermal, and dielectric properties were investigated by FTIR, DSC, and impedance analyzer. Results indicate that more Q3 and Q4 would form at the sample with the same amount of La2O3 and CeO2, meaning the most compact structure, while more La2O3 would lead to a loosen network. Meanwhile, glasses obtained the best dielectric properties here, and the dips in dielectric constant and loss are ascribed to the structural changes in the glass network. The glass transition temperature, Tg ascends first and then declines, due to the variation of bond strength and non-bridge oxygen content, as well as changes in field strength. Parameters for thermal stability decrease firstly and then increase slightly, indicating small changes in thermal stability. The glass density gradually increases, which is mainly from the small field strength of La3+ ions and the larger molar mass of La2O3.

The Timing Behavior of the Central Compact Object Pulsar 1E 1207.4−5209

Abstract We present 20 yr of timing observations for 1E 1207.4−5209, the central compact object in supernova remnant PKS 1209−51/52, to follow up on our detection of an unexpected timing glitch in its spin-down. Using new XMM-Newton and NICER observations of 1E 1207.4−5209, we now find that the phase ephemeris can be well modeled by either two small glitches, or extreme timing noise. The implied magnitudes of the frequency glitches are and , at epochs 2010.9 and 2014.4, respectively. The updated timing solutions also rule out our previous suggestion of a large glitch in the frequency derivative . No other canonical pulsar with such a small spin-down rate ( Hz s−1) or surface dipole magnetic field strength ( G) has been observed to glitch; the glitch activity parameter of 1E 1207.4−5209 is larger than that of more energetic pulsars. Alternative parameterizations that do not involve glitches can fit the data, but they have timing residuals or a second frequency derivative that are orders of magnitude larger than in pulsars with similar spin-down parameters. These timing properties of 1E 1207.4−5209 further motivate the leading theory of central compact objects, that an initial B-field of normal strength was buried in the neutron star crust by fallback of supernova ejecta, suppressing the surface dipole field. The slow reemergence of the buried field may be involved in triggering glitches or excess timing noise.

Static Polarizabilities at the Basis Set Limit: A Benchmark of 124 Species.

Benchmarking molecular properties with Gaussian-type orbital (GTO) basis sets can be challenging, because one has to assume that the computed property is at the complete basis set (CBS) limit, without a robust measure of the error. Multiwavelet (MW) bases can be systematically improved with a controllable error, which eliminates the need for such assumptions. In this work, we have used MWs within Kohn–Sham density functional theory to compute static polarizabilities for a set of 92 closed-shell and 32 open-shell species. The results are compared to recent benchmark calculations employing the GTO-type aug-pc4 basis set. We observe discrepancies between GTO and MW results for several species, with open-shell systems showing the largest deviations. Based on linear response calculations, we show that these discrepancies originate from artifacts caused by the field strength and that several polarizabilies from a previous study were contaminated by higher order responses (hyperpolarizabilities). Based on our MW benchmark results, we can affirm that aug-pc4 is able to provide results close to the CBS limit, as long as finite difference effects can be controlled. However, we suggest that a better approach is to use MWs, which are able to yield precise finite difference polarizabilities even with small field strengths.

The Effect of F‐Layer Zonal Neutral Wind on the Monthly and Longitudinal Variability of Equatorial Ionosphere Irregularity and Drift Velocity

AbstractThe effect of eastward zonal wind speed (EZWS) on vertical drift velocity (E × Bdrift) that mainly controls the equatorial ionospheric irregularities has been explained theoretically and through numerical models. However, its effect on the seasonal and longitudinal variations of E × B and the accompanying irregularities has not yet been investigated experimentally due to lack of F‐layer wind speed measurements. Observations of EZWS from GOCE and ion density and E × B from C/NOFS satellites for years 2011 and 2012 during quite times are used in this study. Monthly and longitudinal variations of the irregularity occurrence, E × B, and EZWS show similar patterns. We find that at most 50.85% of longitudinal variations of E × B can be explained by the longitudinal variability of EZWS only. When the EZWS exceeds 150 m/s, the longitudinal variation of EZWS, geomagnetic field strength, and Pedersen conductivity explain 56.40–69.20% of the longitudinal variation of E × B. In Atlantic, Africa, and Indian sectors, from 42.63% to 79.80% of the monthly variations of the E × B can be explained by the monthly variations of EZWS only. It is found also that EZWS and E × B may be linearly correlated during fall equinox and December solstice. The peak occurrence of irregularity in the Atlantic sector during November and December is due to the combined effect of large wind speed, solar terminator‐geomagnetic field alignment, and small geomagnetic field strength and Pedersen conductivity. Moreover, during June solstices, small EZWS corresponds to vertically downward E × B, which suggests that other factors dominate the E × B drift rather than the EZWS during these periods.

ACCELERATION OF PARTICLES BY INTENSIVE ELECTROMAGNETIC FIELDS IN A VACUUM WITH EXTERNAL MAGNETIC FIELD

The possibilities and conditions of effective interaction, in particular acceleration, of charged particles by the field of an intense plane electromagnetic wave in the presence of an external constant magnetic field are considered. It is shown that the well-known conditions of cyclotron resonances require generalization. New conditions for the resonant interaction of charged particles are formulated, which contain not only the strength of the external magnetic field (as the well-known conditions of cyclotron resonances) but also the field strength of the wave. Cases of both small wave field strengths, so large, are considered. It is shown that new resonance conditions open up new possibilities for effective particle acceleration.

Ground-state properties of spin–orbit-coupled dipolar Bose–Einstein condensates with in-plane gradient magnetic field

We investigate the ground-state properties of spin–orbit-coupled pseudo-spin-1/2 dipolar Bose–Einstein condensates in a two-dimensional harmonic trap and an in-plane quadrupole field. The effects of spin–orbit coupling (SOC), dipole–dipole interaction (DDI) and the in-plane quadrupole field on the ground-state structures and spin textures of the system are systematically analyzed and discussed. For fixed SOC and DDI strengths, the system shows a quadrupole stripe phase with a half-quantum vortex, or a quadrupole Thomas–Fermi phase with a half-quantum antivortex for small quadrupole field strength, depending on the ratio between inter- and intraspecies interaction. As the quadrupole field strength enhances, the system realizes a ring mixed phase with a hidden vortex–antivortex cluster rather than an ordinary giant vortex in each component. Of particular interest, when the strengths of DDI and quadrupole field are fixed, strong SOC leads to the formation of criss-crossed vortex string structure. For given SOC and quadrupole field, the system for strong DDI displays a sandwich-like structure, or a special delaminated structure with a prolate antivortex in the spin-up component. In addition, typical spin textures for the ground states of the system are analyzed. It is shown that the system sustains exotic topological structures, such as a hyperbolic spin domain wall, skyrmion-half-antiskyrmion-antiskyrmion lattice, half-skyrmion-skyrmion-half-antiskyrmion lattice, and a drum-shaped antimeron.