Self-organized Domain Research Articles

Motility-induced coexistence of a hot liquid and a cold gas

If two phases exist at the same time, such as a gas and a liquid, they have the same temperature. This fundamental law of equilibrium physics is known to apply even to many non-equilibrium systems. However, recently, there has been much attention in the finding that inertial self-propelled particles like Janus colloids in a plasma or microflyers could self-organize into a hot gas-like phase that coexists with a colder liquid-like phase. Here, we show that a kinetic temperature difference across coexisting phases can occur even in equilibrium systems when adding generic (overdamped) self-propelled particles. In particular, we consider mixtures of overdamped active and inertial passive Brownian particles and show that when they phase separate into a dense and a dilute phase, both phases have different kinetic temperatures. Surprisingly, we find that the dense phase (liquid) cannot only be colder but also hotter than the dilute phase (gas). This effect hinges on correlated motions where active particles collectively push and heat up passive ones primarily within the dense phase. Our results answer the fundamental question if a non-equilibrium gas can be colder than a coexisting liquid and create a route to equip matter with self-organized domains of different kinetic temperatures.

Optical transmission modulation and spectral properties of self-organized nematic domains

The modulation and spectral characteristics of self-organized ensembles of nematic domains with the disclination lines non-aligned and aligned in a magnetic field have been studied using an electric field. The obtained experimental voltage dependences of the light transmission agree well with the dependences calculated using the model considerations. These dependences have been compared with the electro-optical characteristics of a homogeneous planar nematic layer. The amplitude component of the optical transmission determined by light scattering and the oscillating component caused by the phase modulation have been examined. The effect of the spectral dispersion of transmission on the electro-optical characteristics of domain ensembles has been evaluated.

Self-organized formation of domain arrays in TGS crystal by moving SPM tip

In this paper, we studied the formation of self-organized domain arrays created by moving biased tip of scanning probe microscope (SPM) in deuterated TGS crystals. The shape of created domains depends significantly on scanning direction and applied voltage. For scanning along c axis, the domain shape drastically changed from arrays to stripe domains at 150[Formula: see text]V. Scanning perpendicular to [Formula: see text] axis led to formation of the array of the dashed domains. Increasing of the dashed domain length leads to change of domain shape from arrays of dashed domains to solid stripe domain. The obtained effect has been considered in terms of the kinetic approach as a result of formation of comb-like domain with charged domain walls in the bulk due to repetitive appearance of the domain spikes. The spontaneous backswitching under the action of the depolarization field leads to the fast growth of the tooth to the surface and results in the transformation of the domain shape. The computer simulation of the nonuniform motion of charged domain wall under the action of depolarization field has been done. The obtained results demonstrate the essential role of screening processes and pave the way for further improvement of domain engineering methods.

Structure and Optical Properties of Self-Organized Nematic Domains Ensembles on Polycarbonate Surface

Structure and Optical Properties of Self-Organized Nematic Domains Ensembles on Polycarbonate Surface

Formation of self-organizing functionally distinct Rho of plants domains involves a reduced mobile population.

Rho family proteins are central to the regulation of cell polarity in eukaryotes. Rho of Plants-Guanyl nucleotide Exchange Factor (ROPGEF) can form self-organizing polar domains following co-expression with an Rho of Plants (ROP) and an ROP GTPase-Activating Protein (ROPGAP). Localization of ROPs in these domains has not been demonstrated, and the mechanisms underlying domain formation and function are not well understood. Here we show that six different ROPs form self-organizing domains when co-expressed with ROPGEF3 and GAP1 in Nicotiana benthamiana or Arabidopsis (Arabidopsis thaliana). Domain formation was associated with ROP-ROPGEF3 association, reduced ROP mobility, as revealed by time-lapse imaging and Fluorescence Recovery After Photobleaching beam size analysis, and was independent of Rho GTP Dissociation Inhibitor mediated recycling. The domain formation depended on the ROPs' activation/inactivation cycles and interaction with anionic lipids via a C-terminal polybasic domain. Coexpression with the microtubule-associated protein ROP effector INTERACTOR OF CONSTITUTIVELY ACTIVE ROP 1 (ICR1) revealed differential function of the ROP domains in the ability to recruit ICR1. Taken together, the results reveal mechanisms underlying self-organizing ROP domain formation and function.

Nano-imaging of strain-tuned stripe textures in a Mott crystal

The 4d transition metal perovskites Can+1RunO3n+1 have attracted interest for their strongly interacting electronic phases showing pronounced sensitivity to controllable stimuli like strain, temperature, and even electrical current. Through multi-messenger low-temperature nano-imaging, we reveal a spontaneous striped texture of coexisting insulating and metallic domains in single crystals of the bilayer ruthenate Ca3(TixRu1-x)2O7 across its first-order Mott transition at T approx 95K. We image on-demand anisotropic nucleation and growth of these domains under in situ applied uniaxial strain rationalized through control of a spontaneous Jahn-Teller distortion. Our scanning nano-susceptibility imaging resolves the detailed susceptibility of coexisting phases to strain and temperature at the transition threshold. Comparing these nano-imaging results to bulk-sensitive elastoresistance measurements, we uncover an emergent “domain susceptibility” sensitive to both the volumetric phase fractions and elasticity of the self-organized domain lattice. Our combined susceptibility probes afford nano-scale insights into strain-mediated control over the insulator-metal transition in 4d transition metal oxides.

Emergence of Self-Organized Dynamical Domains in a Ring of Coupled Population Oscillators

We show that interactions of inherently chaotic oscillators can lead to coexistence of regular oscillatory regimes and chaotic oscillations in the rings of coupled oscillators provided that the level of interaction between the oscillators exceeds a threshold value. The transformation of the initially chaotic dynamics into the regular dynamics in a number of the coupled oscillators is shown to result from suppression of chaos by separation of certain oscillation periods from the continuous spectra, which are characteristic of chaotic oscillations.

Formation of submicron stripe domain ensembles during polarization reversal in Rb doped KTP crystal covered by dielectric layer

The formation of self-organized quasi-regular domain structure in Rb:KTP crystals covered by photoresist layer was studied. The instability of domain wall shape resulting in formation of domain streamers on the wall was revealed. The streamers structure appeared on Z+ polar surface and grew in polar direction. The minimal obtained structure period was 1 µm and the structure length reached 50 μm. The width of the stripe domains between the neighboring streamers went down to 100 nm and the resulting aspect ratio was 500. The obtained effect is very promising for the submicron periodical poling in the crystals of KTP family.

Nature of protected zero-energy states in Penrose quasicrystals

The electronic spectrum of the Penrose rhombus quasicrystal exhibits a macroscopic fraction of exactly degenerate zero energy states. In contrast to other bipartite quasicrystals, such as the kite-and-dart one, these zero energy states cannot be attributed to a global mismatch $\Delta n$ between the number of sites in the two sublattices that form the quasicrystal. Here, we argue that these zero energy states are instead related to a local mismatch $\Delta n(\bf r)$. Although $\Delta n(\bf r)$ averages to zero, its staggered average over self-organized domains gives the correct number of zero energy states. Physically, the local mismatch is related to a hidden structure of nested self-similar domains that support the zero energy states. This allows us to develop a real space renormalization-group scheme, which yields the scaling law for the fraction of zero energy states, $Z$, versus size of their support domain, $N$, as $Z\propto N^{-\eta}$ with $\eta =1-\ln 2/\ln(1+\tau) \approx 0.2798$ (where $\tau$ is the golden ratio). It also reproduces the known total fraction of the zero energy states, $81-50\tau\approx 0.0983$. We also show that the exact degeneracy of these states is protected against a wide variety of local perturbations, such as irregular or random hopping amplitudes, magnetic field, random dilution of the lattice, etc. We attribute this robustness to the hidden domain structure and speculate about its underlying topological origin.

Effect of thermal annealing on the morphology of sol–gel processed barium strontium titanate thin films: Consequences on electrical properties

The link between the morphology and the electrical properties of the sol–gel processed Ba0.7Sr0.3TiO3 thin films is investigated. Previous studies have not fully explained the differences in growth morphology as a function of the elaboration conditions. The thin films were investigated by Grazing Incidence Small-Angle X-ray Scattering (GISAXS), x-ray diffraction, and scanning electron microscopy. More precisely, prototype films were studied as a function of the annealing temperature: at low temperatures (140 °C–200 °C) by in situ GISAXS and at high temperatures (600 °C–800 °C) by ex situ GISAXS. At ∼150 °C, self-organized domains with a preferential distance of approximately 14 nm are formed. At high annealing temperatures, the growing domains become either nanoparticles or pores with a preferential distance of approximately 85 nm at 600 °C. This growth evolution is successfully explained by a general model based on convection and evaporation. With thermal annealing, the characteristic lengths parallel to the surface increase due to convection and the characteristic lengths perpendicular to the surface decrease due to evaporation. In addition, two types of annealing were investigated at 700 °C. For annealing after each other layer, a growth with vertically shifted particles occurs with no ferroelectric behavior. On the contrary, for annealing after each deposited layer, a columnar growth occurs and a ferroelectric hysteresis loop is obtained. The ferroelectricity of the sol–gel barium strontium titanate thin films is definitely linked to the complete removal of organic constituents leading to columnar growth.

Self-organized bosonic domain walls

Hardcore bosons on honeycomb lattice ribbons with zigzag edges are studied using exact numerical simulations. We map out the phase diagrams of ribbons with different widths, which contain superfluid and insulator phases at various fillings. We show that charge domain walls are energetically favorable, in sharp contrast to the more typical occupation of a set of sites on a single sublattice of the bipartite geometry at $\rho=\frac{1}{2}$ filling. This `self-organized domain wall' separates two charge-density-wave (CDW) regions with opposite Berry curvatures. Associated with the change of topological properties, superfluid transport occurs down the domain wall. Our results provide a concrete context to observe bosonic topological phenomena and can be simulated experimentally using bosonic cold atoms trapped in designed optical lattices.

Formation of the maze domain structures in lithium niobate as a result of multiple pulse irradiation by infrared laser

The formation of the maze domain structures in the plates of congruent lithium niobate single crystal caused by multiple irradiation of infrared pulsed laser at different plate temperatures was studied. Four stages of domain evolution with increasing pulse number were distinguished. The dependence of the formed self-organizing domain structures on pulse number and sample temperature was revealed. Suppression of the domain formation at the elevated temperatures was attributed to increasing ionic conductivity, which led to decreasing the switching field.

Self-organized domain formation by moving the biased SPM tip

We studied the domain structure self-organization at non-polar cuts of congruent lithium niobate under the action of biased moving scanning probe microscopy (SPM) tip. Analysis of the obtained domain structures revealed several types of switching: doubling, quadrupling, and chaotic. The period of created domains was shown to be similar in different non-polar cuts. The obtained results give further insight into domain interaction and domain structure self-organization.

Control of the stripe domain pattern in L10-ordered FePd thin films

Abstract L10-ordered FePd thin films with strong perpendicular magnetic anisotropy and self-organized domain patterns have been prepared using molecular beam epitaxy. We demonstrate reproducible growth methods for controlling the strength of the anisotropy and the lateral domain patterns. Neutron scattering experiments have been used to probe the FePd domain structure and were compared with simulations in the framework of the Distorted Wave Born Approximation.

Self-Organized Ferroelectric Domains Controlled by a Constant Bias from the Atomic Force Microscopy Tip.

The ferroelectric polarization switching along an external electric field is most important for the applications of ferroelectric memories and piezoelectric sensors and actuators; however, the depolarization commonly occurs randomly and cannot be controlled exactly until now. Here, a tip bias introduces the polarization switching and a ∼10 μm-scale domain in a triglycine sulfate crystal, and then the polarization backswitching as a special depolarization introduces a series of ordered granular domains along a line being parallel to the c axis and through the tip which divides the original domain to two similar parts. Such backswitching is controlled by the surface charge change as a result of the interplay among polarization charges, mobile H+ ions at the surface, and the strong crystal anisotropy. The self-organized ferroelectric domains offer us a new freedom to design novel ferroelectric or piezoelectric devices in future.

The phase-field modeling of the self-organized phase growth with three-fold symmetry

The formation of self-organized domain patterns during polarization reversal in highly non-equilibrium switching conditions was studied by us earlier in the single crystals of lithium niobate and lithium tantalate. In this paper, we used the phase-field simulation to verify the analogy between self-organized growth of domains and new phase during the first order phase transition. The crystal symmetry C3v was taken into account. The similarity of simulated and experimentally observed shapes of isolated domains was achieved.

The Formation of Self-Organized Domain Structures at Non-Polar Cuts of Lithium Niobate as a Result of Local Switching by an SPM Tip.

We have studied experimentally the interaction of isolated needle-like domains created in an array via local switching using a biased scanning probe microscope (SPM) tip and visualized via piezoelectric force microscopy (PFM) at the non-polar cuts of MgO-doped lithium niobate (MgOLN) crystals. It has been found that the domain interaction leads to the intermittent quasiperiodic and chaotic behavior of the domain length in the array in a manner similar to that of polar cuts, but with greater spacing between the points of bias application and voltage amplitudes. It has also been found that the polarization reversal at the non-polar cuts and domain interaction significantly depend on humidity. The spatial distribution of the surface potential measured by Kelvin probe force microscopy in the vicinity of the charged domain walls revealed the decrease of the domain length as a result of the partial backswitching after pulse termination. The phase diagram of switching behavior as a function of tip voltage and spacing between the points of bias application has been plotted. The obtained results provide new insight into the problem of the domain interaction during forward growth and can provide a basis for useful application in nanodomain engineering and development of non-linear optical frequency converters, data storage, and computing devices.

Formation of self-organized domain structures with charged domain walls in lithium niobate with surface layer modified by proton exchange

We have studied the self-organized dendrite domain structures appeared as a result of polarization reversal in the uniform field in lithium niobate single crystals with the artificial surface layer created by proton exchange. We have revealed the self-organized sub-micron scale dendrite domain patterns consisting of domain stripes oriented along the X crystallographic directions separated by arrays of dashed residual domains at the surface by scanning probe microscopy. Raman confocal microscopy allowed visualizing the quasi-regular dendrite domain structures with similar geometry in the vicinity of both polar surfaces. The depth of the structure was about 20 μm for Z+ polar surface and 70 μm for Z− one. According to the proposed mechanism, the dendrite structure formation at the surface was related to the ineffective screening of the residual depolarization field. The computer simulation of the structure formation based on the cellular automata model with probabilistic switching rule proved the eligibility of the proposed scheme, the simulated dendrite domain patterns at various depths being similar to the experimental ones.

Interface-mediated ferroelectric patterning and Mn valency in nano-structured PbTiO3/La0.7Sr0.3MnO3

We employed a multitechnique approach using piezo-force response microscopy and photoemission microscopy to investigate a self-organizing polarization domain pattern in PbTiO3/La0.7Sr0.3MnO3 (PTO/LSMO) nanostructures. The polarization is correlated with the nanostructure morphology as well as with the thickness and Mn valence of the LSMO template layer. On the LSMO dots, the PTO is upwards polarized, whereas outside the nanodots, the polarization appears both strain and interface roughness dependent. The results suggest that the electronic structure and strain of the PTO/LSMO interface contribute to determining the internal bias of the ferroelectric layer.

X-ray white beam topography of self-organized domains in flux-grownBaTiO3single crystals

The phenomenon of self-organization of domains into a ``square-net pattern'' in single-crystal, flux-grown $\mathrm{BaTi}{\mathrm{O}}_{3}$ several degrees below the ferroelectric to paraelectric phase transition was investigated using in situ synchrotron x-ray topography. The tetragonal distortion of the crystal was determined by measuring the angular separation between the diffraction images received from 90\ifmmode^\circ\else\textdegree\fi{} $a$ and $c$ domains in the projection topographs, and shows a rapid decrease towards 110 \ifmmode^\circ\else\textdegree\fi{}C, the onset temperature for self-organization. The onset of self-organization is accompanied by bending of the ${100}$ lattice planes parallel to the crystal surface, which produces a strain that persists up to and beyond the Curie temperature, where the crystal becomes cubic and the self-organized domains disappear. At the Curie point, the bending angle ${\ensuremath{\alpha}}_{100}=8.1(\ifmmode\pm\else\textpm\fi{}0.3)\phantom{\rule{0.16em}{0ex}}\mathrm{mrad}$ is at a maximum and corresponds to the radius of curvature of the surface being 16.3(\ifmmode\pm\else\textpm\fi{}0.6) mm.