Stable Stripes Research Articles

Strain-modulated intercalated phases of Pb monolayer with dual periodicity in SiC(0001)-graphene interface

Intercalation of metal atoms at the SiC(0001)-graphene (Gr) interface can provide confined 2D metal layers with interesting electronic properties. The intercalated Pb monolayer (ML) has shown the coexistence of the Gr(10 × 10)-moiré and a stripe phase, which still lacks understanding. Using density functional theory calculation and thermal annealing with ab initio molecular dynamics as motivated by experiment, we have studied the formation energy of Gr/Pb/SiC(0001) for different Pb coverages. Near the coverage of a Pb(111)-like ML mimicking the (10 × 10)-moiré, we find a slightly more stable stripe structure, where one half of the structure has compressive strain with Pb occupying the Si-top sites and the other half has tensile strain with Pb off the Si-top sites. This stripe structure along the Gr zigzag direction has a periodicity of 2.3 nm across the [1 2¯ 10] direction agreeing with the previous observations using scanning tunneling microscopy. Analysis with electron density difference and density of states show the tensile region has a more metallic character than the compressive region, while both are dominated by charge transfer from Pb ML to SiC(0001). The small energy difference between the stripe and Pb(111)-like structures means the two phases are almost degenerate and can coexist, which explains the experimental observations.

Pattern dynamics of a Lotka-Volterra model with taxis mechanism

This paper deals with the Turing bifurcation and pattern dynamics of a Lotka-Volterra model with the predator-taxis and the homogeneous no-flux boundary conditions. To investigate the pattern dynamics, we first give the occurrence conditions of the Turing bifurcation. It is found that there is no Turing bifurcation when predator-taxis disappears, while the Turing bifurcation occurs as predator-taxis is presented. Next, we establish the amplitude equation by virtue of weakly nonlinear analysis. Our theoretical result suggests the Lotka-Volterra model admits the supercritical or subcritical Turing bifurcation. In this manner, we can determine the stability of the bifurcating solution. Finally, some numerical simulation results verify the validity of the theoretical analysis. The stripe pattern, the mixed patterns, and wave patterns are performed. Interestingly, the stable stripe patterns will be broken and become wave patterns when the predator-taxis parameter is far from the Turing bifurcation critical point.

Stable stripe and vortex solitons in two-dimensional spin-orbit coupled Bose–Einstein condensates

We present a flexible manipulation and control of solitons via Bose–Einstein condensates. In the presence of Rashba spin–orbit coupling and repulsive interactions within a harmonic potential, our investigation reveals the numerical local solutions within the system. By manipulating the strength of repulsive interactions and adjusting spin–orbit coupling while maintaining a zero-frequency rotation, diverse soliton structures emerge within the system. These include plane-wave solitons, two distinct types of stripe solitons, and odd petal solitons with both single and double layers. The stability of these solitons is intricately dependent on the varying strength of spin–orbit coupling. Specifically, stripe solitons can maintain a stable existence within regions characterized by enhanced spin–orbit coupling while petal solitons are unable to sustain a stable existence under similar conditions. When rotational frequency is introduced to the system, solitons undergo a transition from stripe solitons to a vortex array characterized by a sustained rotation. The rotational directions of clockwise and counterclockwise are non-equivalent owing to spin–orbit coupling. As a result, the properties of vortex solitons exhibit significant variation and are capable of maintaining a stable existence in the presence of repulsive interactions.

Structure and stripe domain of melt-spun HoMn6Sn6-xGax ribbons

Topological magnetic skyrmions are expected to become a new generation of information carrier units, and exploring new magnetic skyrmion host materials and their magnetic domain structures is critical. This paper prepared HoMn6Sn6-xGax ribbons by melt-spinning and annealing and studied the effects of the second phase and doping Ga on the structure and magnetic domain of the ribbons. The results show that doped Ga only replaces the Sn sites in the HoMn6Sn6 phase, and the maximum substitution rate of Ga in the HoMn6Sn6 phase is close to 1/6. The unequal substitution of crystal positions causes the lattice to bear considerable compressive stress and negative strain. With an increase in doped Ga content, the lattice constant and cell volume of the HoMn6Sn6-xGax phase gradually decrease, and the substitution positions also change from mainly occupying Sn(2c) sites to occupying Sn(2e) and Sn(2d) sites simultaneously. Doping Ga enhances the preferential orientation in the grains, Ga occupying Sn(2d) sites enhances 〈009〉 orientation, and occupying Sn(2e) sites contributes to the enhancement in 〈204〉 orientation. Whether doped with Ga or not, the ribbons have stable stripe domains with HoMn6Sn6 structure. Increasing Ga content from x = 0.3 to x = 1.6 decreases the spin reorientation temperature, Curie temperatures, and the difference between the two temperatures.

Molecular characterization and validation of adult-plant stripe rust resistance gene Yr86 in Chinese wheat cultivar Zhongmai 895.

Adult-plant stripe rust resistance gene Yr86 in Chinese wheat cultivar Zhongmai 895 was mapped to the physical interval 710.2-713.2Mb on the long arm of chromosome 2A. Adult-plant resistance to stripe rust is generally more durable than all-stage resistance. Chinese wheat cultivar Zhongmai 895 showed stable stripe rust resistance at the adult-plant stage. To map the genetic loci underlying its resistance, 171 doubled haploid (DH) lines from a Yangmai 16/Zhongmai 895 cross were genotyped with the wheat 660K SNP chip. Disease severities of the DH population and parents were assessed in four environments. A major QTL designated QYryz.caas-2AL was mapped to interval 703.7-715.3Mb on the long arm of chromosome 2A using both chip-based and KASP (kompetitive allele-specific PCR) marker-based methods, explaining 31.5 to 54.1% of the phenotypic variances. The QTL was further validated in an F2 population of cross Emai 580/Zhongmai 895 with 459 plants and a panel of 240 wheat cultivars using KASP markers. Three reliable KASP markers predicted a low frequency (7.2-10.5%) of QYryz.caas-2AL in the test panel and remapped the gene to the physical interval 710.2-713.2Mb. Based on different physical positions or genetic effects from known genes or QTL on chromosome arm 2AL, the gene was predicted to be a new one for adult-plant stripe rust resistance and was named Yr86. Twenty KASP markers linked to Yr86 were developed in this study based on wheat 660K SNP array and genome re-sequencing. Three of them are significantly associated with stripe rust resistance in natural population. These markers should be useful for marker-assisted selection and also provide a starting point for fine mapping and map-based cloning of the new resistance gene.

Metastable supersolid in spin-orbit-coupled Bose-Einstein condensates

Supersolid is a special state of matter with both superfluid properties and spontaneous modulation of particle density. In this paper, we focus on the supersolid stripe phase realized in a spin-orbit coupled Bose-Einstein condensate and explore the properties of a class of metastable supersolids. In particular, we study a one-dimensional supersolid whose characteristic wave number $k$ (magnitude of wave vector) deviates from $k_{m}$, i.e., the one at ground state. In other words, the period of density modulation is shorter or longer than the one at ground state. We find that this class of supersolids can still be stable if their wave numbers fall in the range $k_{c1}<k<k_{c2}$, with two thresholds $k_{c1}$ and $k_{c2}$. Stripes with $k$ outside this range suffer from dynamical instability with complex Bogoliubov excitation spectrum at long wavelength. Experimentally, these stripes with $k$ away from $k_m$ are accessible by exciting the longitudinal spin dipole mode, resulting in temporal oscillation of stripe period as well as $k$. Within the mean-field Gross-Pitaevskii theory, we numerically confirm that for a large enough amplitude of spin dipole oscillation, the stripe states become unstable through breaking periodicity, in qualitative agreement with the existence of thresholds of $k$ for stable stripes. Our work extends the concept of supersolid and uncovers a new class of metastable supersolids to explore.

Spinor condensate in spin–orbit coupled Bose gases with inhomogeneous magnetic field

In this paper, we study the dynamic properties of spin–orbit coupling (SOC) spin-1 antiferromagnetic Bose–Einstein condensates with inhomogeneous external magnetic field by numerical simulations of the multicomponent Gross–Pitaevskii equation. Our results show that the spin dynamics process is greatly affected by SOC when the system is in the absence of magnetic field. The periodicity of spin exchange dynamics disappears and the population of thermal clouds for [Formula: see text] and [Formula: see text] gradually increases and decreases and then reaches a steady value. In this case, a stable stripe phase emerges for three-component wavefunction. Nevertheless, the spin dynamics process becomes complex in the presence of magnetic field, depending on the competition between magnetic field and SOC. The influences of SOC are masked by the relatively strong magnetic field and the density structures are similar to the case of without or weak magnetic field.

Mapping a stable adult-plant stripe rust resistance QTL on chromosome 6AL in Chinese wheat landrace Yibinzhuermai

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases threatening the yield and stability of wheat production in China and many other countries. Identification and utilization of new genes for durable stripe rust resistance are important for ongoing control of this disease. The objectives of this study were to identify quantitative trait loci (QTL) associated with adult-plant stripe rust resistance in the Chinese wheat landrace Yibinzhuermai (YBZR) and to provide wheat breeders with new sources of potentially durable resistance. A total of 117 recombinant inbred lines (RILs) (F5:8) derived from a cross between YBZR and highly susceptible cultivar Taichung 29 (TC29) were assessed for stripe rust severity in field experiments at Wenjiang in 2016 and 2017 and Chongzhou in 2016, 2017, 2018, and 2019 in Sichuan following inoculation with a mixture of current Pst races. The RILs were genotyped using the Wheat55K single nucleotide polymorphism (SNP) array. Three QTL were identified on chromosome arms 6AL, 5BL and 7DS. QYr.YBZR-6AL and QYr.YBZR-7DS conferred major effects in all field environments, explaining 10.6% to 14.7% and 11.5% to 21.2% of phenotypic variation, respectively. The QTL on 5BL and 7DS likely correspond to previously known QTL, whereas QYr.YBZR-6AL is probably novel. Haplotype analysis revealed that the resistance allele at QYr.YBZR-6AL was present in 2.8% of 324 Chinese wheat landraces. SNP markers closely linked with QYr.YBZR-6AL were converted to kompetitive allele-specific PCR markers and validated in the RIL population and a subset of 92 wheat cultivars. QYr.YBZR-6AL and its markers should be useful in breeding programs to improve the level and durability of stripe rust resistance.

Measuring surface tension coefficient of liquid by “phase standing wave” method

&lt;sec&gt;The surface tension of liquid is an important parameter to characterize the properties of liquid. The non-contact method of measuring the surface tension coefficient of liquid has the advantages of being fast, non-destructive, simple and practical. A new non-contact method of measuring the surface tension coefficient of transparent liquid based on the theory of light propagation is developed, and a special phenomenon of “self-interference” is discovered. The “Phase Standing Wave” theory is proposed to explain the phenomenon.&lt;/sec&gt;&lt;sec&gt;The surface wave of the liquid is excited by a frequency-adjustable vibration source (oscillator), and it propagates dynamically in the form of oscillator and cosine wave. When the white light source or laser is incident on the liquid surface obliquely, the phase distribution (cosine-like wave) generated by the light wave carrying the surface wave is first incident on the white paper which is located at the bottom of liquid, and the oscillator will also form the oscillator shadow on the white paper. The phase distribution of the light wave on the white paper spreads around dynamically in the form of cosine wave centering on the oscillator shadow. After diffuse reflection from the white paper, part of the diffuse reflection light in the observation direction carries the dynamic phase generated by the surface wave the first time back to the liquid surface and meets the surface wave again. After the light wave passes through the surface, it carries the phase generated by the surface wave the second time, that is, the superposition of two surface waves occurs in the phase of the light wave. In the phase of the light wave, the phase wave of the oscillator will propagate in the direction of the oscillator shadow, and the phase wave of the oscillator shadow will propagate in the direction of the oscillator.&lt;/sec&gt;&lt;sec&gt;According to the conditions of forming standing waves, two surface waves propagating in the opposite directions can form standing waves, so the phase standing waves can exist only within a relatively small range between the oscillator and the oscillator shadow. Thus the dark and bright “self-interference” with stable stripes can be observed in the far field. When white light and laser are used as light sources respectively, the fringe spacing remains unchanged, indicating that the fringe spacing is independent of the wavelength of incident light, and the light wave is only the carrier of the mechanical wave phase. The light waves with different wavelengths and coherences have no influence on the experimental measurement results.&lt;/sec&gt;&lt;sec&gt;The fringe spacing is measured automatically by analyzing and processing the image captured by camera. According to the dispersion relationship of surface waves, the surface tension coefficient of water is obtained automatically and accurately. The experimental setup is simple and easy to operate, the experimental phenomenon is intuitive, the stripes are clear and stable, and the anti-interference capability is strong, and can be observed in all directions. It can be widely used to measure the surface tension coefficients of other transparent liquids.&lt;/sec&gt;

Single infrared image stripe removal via deep multi-scale dense connection convolutional neural network

Stripe noise removal is a crucial step for the infrared imaging system. Existing stripe removal methods are hard to balance stripe removal and image details preservation. In this paper, a deep multi-scale dense connection convolutional neural network (DMD-CNN) is proposed to address this problem. In DMD-CNN, a multi-scale feature representation unit (FR-Unit) is designed to decompose raw image into different scales which can extract diverse fine and coarse features. Dense connection is introduced into the network, which makes full use of the multi-scale information obtained by FR-Unit and avoids performance degradation. Moreover, the regularization term Lh is defined to depict the vertical direction smoothness property of stripe. Experiment results show that DMD-CNN performs more stable stripe removal effects in different scenes and diverse stripe intensity. Meanwhile, DMD-CNN outperforms seven state-of-the-art stripe removal methods on qualitative and quantitative evaluation.

On the bandwidth of stable nonlinear stripe patterns in finite size systems.

Nonlinear stripe patterns occur in many different systems, from the small scales of biological cells to geological scales as cloud patterns. They all share the universal property of being stable at different wavenumbers q, i.e., they are multistable. The stable wavenumber range of the stripe patterns, which is limited by the Eckhaus- and zigzag instabilities even in finite systems for several boundary conditions, increases with decreasing system size. This enlargement comes about because suppressing degrees of freedom from the two instabilities goes along with the system reduction, and the enlargement depends on the boundary conditions, as we show analytically and numerically with the generic Swift-Hohenberg (SH) model and the universal Newell-Whitehead-Segel equation. We also describe how, in very small system sizes, any periodic pattern that emerges from the basic state is simultaneously stable in certain parameter ranges, which is especially important for the Turing pattern in cells. In addition, we explain why below a certain system width, stripe patterns behave quasi-one-dimensional in two-dimensional systems. Furthermore, we show with numerical simulations of the SH model in medium-sized rectangular domains how unstable stripe patterns evolve via the zigzag instability differently into stable patterns for different combinations of boundary conditions.

Effect of surfactants on the long-wave stability of two-layer oscillatory film flow

The stability of the two-layer film flow driven by an oscillatory plate under long-wave disturbances is studied. The influence of key factors, such as thickness ratio ( $n$ ), viscosity ratio ( $m$ ), density ratio ( $r$ ), oscillatory frequency ( $\beta$ ) and insoluble surfactants on the stability behaviours is studied systematically. Four special Floquet patterns are identified, and the corresponding growth rates are obtained by solving the eigenvalue problem of the fourth-order matrix. A small viscosity ratio ( $m\le 1$ ) may stabilize the flow but it depends on the thickness ratio. If the viscosity ratio is not very small ( $m&gt;0.1$ ), in the $(\beta ,n)$ -plane, stable and unstable curved stripes appear alternately. In other words, under the circumstances, if the two-layer film flow is unstable, slightly adjusting the thickness of the upper film may make it stable. In particular, if the upper film is thin enough, even under high-frequency oscillation, the flow is always stable. The influence of density ratio is similar, i.e. there are curved stable and unstable stripes in the $(\beta ,r)$ -planes. Surface surfactants generally stabilize the flow of the two-layer oscillatory membrane, while interfacial surfactants may stabilize or destabilize the flow but the effect is mild. It is also found that gravity can generally stabilize the flow because it narrows the bandwidth of unstable frequencies.

Controlled Nucleation and Stabilization of Ferroelectric Domain Wall Patterns in Epitaxial (110) Bismuth Ferrite Heterostructures

AbstractFerroelectric domain walls, topological entities separating domains of uniform polarization, are promising candidates as active elements for nanoscale memories. In such applications, controlled nucleation and stabilization of domain walls are critical. Here, using in situ transmission electron microscopy and phase‐field simulations, a controlled nucleation of vertically oriented 109° domain walls in (110)‐oriented BiFeO3 (BFO) thin films is reported. In the switching experiment, reversed domains that are nucleated preferentially at the nanoscale edges of the “crest and sag” pattern‐like electrode under external bias subsequently grow into a stable stripe configuration. In addition, when triangular pockets (with an in‐plane polarization component) are present, these domain walls are pinned to form stable flux‐closure domains. Phase field simulations show that i) field enhancement at the edges of the electrode causes site‐specific domain nucleation, and ii) the local electrostatics at the domain walls drives the formation of flux closure domains, thus stabilizing the striped pattern, irrespective of the initial configuration. The results demonstrate how flux closure pinning can be exploited in conjunction with electrode patterning and substrate orientation to achieve a desired topological defect configuration. These insights constitute critical advancements in exploiting domain walls in next generation ferroelectronic devices.

Stable diagonal stripes in the t\u2013J model at n\u0305h = 1/8 doping from fPEPS calculations

We investigate the two-dimensional t–J model at a hole doping of {bar{n}}_{{rm{h}}}=1/8 using recently developed high accuracy fermionic projected entangled pair states method. By applying the stochastic gradient descent method combined with the Monte Carlo sampling technique, we obtain the ground state hole energy Ehole = −1.621 for J/t = 0.4. We show that the ground state has stable diagonal stripes instead of vertical stripes with a width of 4 unit cells, and stripe filling ρl = 0.5. We further show that the long-range superconductivity order is suppressed at this point.

Cluster stability driven by quantum fluctuations

By means of an accurate path-integral Monte Carlo we investigate a two-dimensional ensemble of particles interacting via a Lifshitz-Petrich-Gaussian potential. In particular, analysing structures described by a commensurate ratio between the two wave numbers that mark the pattern, the Lifshitz-Petrich-Gaussian boson model may display a stable and well-defined stripe phase lacking any global phase coherence but featuring a superfluid signal along the stripe direction only. Upon increasing quantum fluctuations and quantum-mechanical exchange of bosons, the double-degeneration of the negative minima in the Fourier transform of the potential is removed at the expense of a density modulation peculiar to a cluster triangular crystal. We also show that this last structure possess all features adhering to the definition of a supersolid phase.

Instructive role of melanocytes during pigment pattern formation of the avian skin

Animal skin pigment patterns are excellent models to study the mechanism of biological self-organization. Theoretical approaches developed mathematical models of pigment patterning and molecular genetics have brought progress; however, the responsible cellular mechanism is not fully understood. One long unsolved controversy is whether the patterning information is autonomously determined by melanocytes or nonautonomously determined from the environment. Here, we transplanted purified melanocytes and demonstrated that melanocytes could form periodic pigment patterns cell autonomously. Results of heterospecific transplantation among quail strains are consistent with this finding. Further, we observe that developing melanocytes directly connect with each other via filopodia to form a network in culture and in vivo. This melanocyte network is reminiscent of zebrafish pigment cell networks, where connexin is implicated in stripe formation via genetic studies. Indeed, we found connexin40 (cx40) present on developing melanocytes in birds. Stripe patterns can form in quail skin explant cultures. Several calcium channel modulators can enhance or suppress pigmentation globally, but a gap junction inhibitor can change stripe patterning. Most interestingly, in ovo, misexpression of dominant negative cx40 expands the black region, while overexpression of cx40 expands the yellow region. Subsequently, melanocytes instruct adjacent dermal cells to express agouti signaling protein (ASIP), the regulatory factor for pigment switching, which promotes pheomelanin production. Thus, we demonstrate Japanese quail melanocytes have an autonomous periodic patterning role during body pigment stripe formation. We also show dermal agouti stripes and how the coupling of melanocytes with dermal cells may confer stable and distinct pigment stripe patterns.

Stabilizing a homoclinic stripe

For a large class of reaction-diffusion systems with large diffusivity ratio, it is well known that a two-dimensional stripe (whose cross-section is a one-dimensional homoclinic spike) is unstable and breaks up into spots. Here, we study two effects that can stabilize such a homoclinic stripe. First, we consider the addition of anisotropy to the model. For the Schnakenberg model, we show that (an infinite) stripe can be stabilized if the fast-diffusing variable (substrate) is sufficiently anisotropic. Two types of instability thresholds are derived: zigzag (or bending) and break-up instabilities. The instability boundaries subdivide parameter space into three distinct zones: stable stripe, unstable stripe due to bending and unstable due to break-up instability. Numerical experiments indicate that the break-up instability is supercritical leading to a 'spotted-stripe' solution. Finally, we perform a similar analysis for the Klausmeier model of vegetation patterns on a steep hill, and examine transition from spots to stripes.This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)'.

Continuation and Bifurcation of Grain Boundaries in the Swift--Hohenberg Equation

We study grain boundaries between striped phases in the prototypical Swift-Hohenberg equation. We propose an analytical and numerical far- field-core decomposition that allows us to study existence and bifurcations of grain boundaries analytically and numerically using continuation techniques. This decomposition overcomes problems with computing grain boundaries in a large doubly periodic box with phase conditions. Using the spatially conserved quantities of the time-independent Swift-Hohenberg equation, we show that symmetric grain boundaries must select the marginally zig-zag stable stripes. We find that as the angle between the stripes is decreased, the symmetric grain boundary undergoes a parity-breaking pitchfork bifurcation where dislocations at the grain boundary split into disclination pairs. A plethora of asymmetric grain boundaries (with different angles of the far- field stripes either side of the boundary) is found and investigated. The energy of the grain boundaries is then mapped out. We find that when the angle between the stripes is greater than a critical angle, the symmetric grain boundary is energetically preferred while when the angle is less than the critical angle, the grain boundaries where stripes on one side are parallel to the interface are energetically preferred. Finally, we propose a classification of grain boundaries that allows us to predict various non-standard asymmetric grain boundaries.

Multiple broken symmetries in stripedLa2−xBaxCuO4detected by the field-symmetric Nernst effect

We report on a thermoelectric investigation of the stripe and superconducting phases of the cuprate La$_{2-x}$Ba$_{x}$CuO$_{4}$ near the $x=1/8$ doping known to host stable stripes. We use the doping and magnetic field dependence of field-symmetric Nernst effect features to delineate the phenomenology of these phases. Our measurements are consistent with prior reports of time-reversal symmetry breaking signatures above the superconducting $T_{{\rm c}}$, and crucially detect a sharp, robust, field-invariant peak at the stripe charge order temperature, $T_{{\rm {\scriptscriptstyle CO}}}$. Our observations suggest the onset of a nontrivial charge ordered phase at $T_{{\rm {\scriptscriptstyle CO}}}$, and the subsequent presence of spontaneously generated vortices over a broad temperature range before the emergence of bulk superconductivity in LBCO.

Approach for making visible and stable stripes in a spin-orbit-coupled Bose-Einstein superfluid

The striped phase exhibited by a spin-$1/2$ Bose-Einstein condensate with spin-orbit coupling is characterized by the spontaneous breaking of two continuous symmetries: gauge and translational symmetry. This is a peculiar feature of supersolids and is the consequence of interaction effects. We propose an approach to produce striped configurations with high-contrast fringes, making their experimental detection in atomic gases a realistic perspective. Our approach, whose efficiency is directly confirmed by three-dimensional Gross-Pitaevskii simulations, is based on the space separation of the two spin components into a two-dimensional bilayer configuration, causing the reduction of the effective interspecies interaction and the increase of the stability of the striped phase. We also explore the effect of a $\pi/2$ Bragg pulse, causing the increase of the fringe wavelength, and of a $\pi/2$ rf pulse, revealing the coherent nature of the order parameter in the spin channel.