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Yu-Xin Xie

Publications and source records attributed to Yu-Xin Xie.

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Exact Scaling Laws and Non-Hermitian Topological Phase Transitions of Active Continuum on Hyperbolic Manifolds

The macroscopic collective motion of active continuum on curved manifolds is conventionally addressed through perturbative dynamic renormalization or finite-element simulations, often obscuring the underlying geometric mechanisms. Here, an exact algebraic framework is established to reformulate the active phase transition on hyperbolic spaces $\mathbb{H}^2$. By rigorously expanding the covariant Navier-Stokes-like equations and applying the Weitzenböck identity, we derive the exact critical threshold $α_c = \frac{5}{4}Dκ^2$ for macroscopic polarization, which is dictated by the geometric mass gap of the Hodge-de Rham Laplacian. We strictly define the parameter subspace $α= 2Dκ^2$ where the topological free energy reaches the Bogomolny-Prasad-Sommerfield (BPS) limit. This enables the reduction of the complex velocity field to Blaschke products via Möbius gauge symmetry. The flat-space limit ($κ\to 0$) exactly degenerates to the topological phase of the classical O(2) model, demonstrating that the constant negative curvature acts as an un-perturbative infrared regularization for non-linear amplitude saturation. Furthermore, mapping the non-variational active convective modes onto the defect translational zero-modes yields an intrinsically non-reciprocal interaction matrix. By analytically extending the singular integral operator of the dynamically condensed defect ring, we identify a macroscopic second-order exceptional point (EP2) characterized by a strictly algebraic dynamic scaling law $τ\sim |Δν|^{-1/2}$. This closed-form theoretical paradigm provides exact solutions for geometric frustration and non-Hermitian topology in soft mechanics.

cond-mat.soft

Electromechanical Domain Wall Propagation in Dielectric Elastomers: An Exact Geometric Resolution via Conformal Mapping

The localized electromechanical phase transition in dielectric elastomers involves complex moving boundaries and severe electrostatic fringe fields driven by high-curvature interfaces. Traditional phenomenological models fundamentally underestimate the configurational forces by completely ignoring the in-plane electric field components and geometric singularities. Here, we present a asymptotically exact geometric framework to resolve the domain wall propagation. By mapping the highly deformed current configuration to a regular parametric strip via conformal mapping, the field singularities are algebraically eliminated. An exact integration by parts directly translates the higher-order geometric metric into a rigorous topological mass term, projecting the global conformal electrostatics into a non-linear $σ$-model Lagrangian density. Incorporating the Gent strain-stiffening model, the continuous translation symmetry yields a Hamiltonian first integral. Eigenvalue analysis and Bogomol'nyi-Prasad-Sommerfield (BPS) bound calculations prove that the domain wall emerges strictly as an asymmetric heteroclinic orbit connecting two saddle points. This geometric resolution provides exact analytical scalings for the localized interface energy, domain wall thickness, and asymptotic decay lengths, eliminating all phenomenological parameters and offering a deterministic paradigm for geometric instabilities in active soft matter.

cond-mat.soft

Symplectic Isomorphism Between Strong-Coupling Criticality and Finite-Strain Bifurcation

The analytical determination of critical scaling in three-dimensional strongly coupled field theories is inherently restricted by the Borel non-summability of perturbative expansions. In this paper, we establish a symplectic isomorphism that maps the infrared dynamics of scalar quantum field theories onto the finite-strain bifurcation mechanics of hyperelastic continua. By reformulating the renormalization group flow as an effective spatial Hamiltonian evolution within a symplectic phase space, we identify the critical fixed point with the spectral degeneration of a continuous Riccati-Lyapunov dynamical system. The algebraic integrity of this geometric correspondence is rigorously verified against exactly solvable limits, recovering both the Gaussian free-field scaling and the localized Jackiw-Rebbi zero-mode of the continuum Su-Schrieffer-Heeger model. Applying this framework to the 3D Ising universality class, we construct a self-consistent algebraic scaling Ansatz for the anomalous dimension $η$. This derivation dispenses with arbitrary perturbative truncations, demonstrating instead that interaction-induced non-perturbative screening emerges as a strict consequence of the nonlinear self-consistency demanded by the continuous Algebraic Riccati Equation. The resulting rational scaling law functions as a geometric Padé approximant that asymptotically satisfies the unitarity bound limits, providing a mathematically transparent, first-principles macroscopic impedance analogue for the dynamic suppression of strong-coupling divergences.

math-ph

Higher-Order Topological Phase Transitions in Continuous Hyperelastic Manifolds: From Surface Wrinkles to Zero-Energy Corner States

Higher-order topological insulators (HOTIs) have revolutionized our understanding of wave localization, extending the bulk-boundary correspondence to lower-dimensional hinges and corners. Thus far, the realization of mechanical HOTIs has relied exclusively on discretely engineered metamaterials or periodic phononic lattices. Here, we report a fundamental paradigm shift by demonstrating that continuous, homogeneous hyperelastic manifolds undergoing finite multiaxial deformations naturally harbor intrinsic higher-order topological phases. By extending the generalized Stroh-Lie impedance formalism into a fully coupled 3D finite-strain framework, we map the highly nonlinear orthotropic geometric frustration onto a four-band effective Dirac Hamiltonian spanned by Clifford $Γ$-matrices. We reveal that macroscopic orthogonal stretches act precisely as competing Dirac mass terms, driving the continuous spatial transitions of topological domain walls and triggering a breakdown of $C_{4v}$ spatial symmetry. Remarkably, we analytically prove that beyond classical 2D surface wrinkling (1st-order topology), concurrent multiaxial extreme compression unconditionally triggers the emergence of 1D hinge states (2nd-order) and completely localized 0D zero-energy corner states (3rd-order). We further extend this static bifurcation framework into the elastodynamic regime, proving the existence of mid-gap localized vibrational modes. The theoretically derived topological phase diagram, nested Wilson loops, and fractional corner charges are comprehensively verified. Finally, we propose a concrete experimental realization using electro-active dielectric elastomers, enabling the dynamic programming of 0D topological singularities.

cond-mat.soft

Elastic Surface Instability as a Topological Phase Transition

The macroscopic instability of soft materials undergoing extreme deformations is traditionally viewed as a pure structural or mechanical failure. Driven by the quest to uncover universal principles across disparate physical systems, we bridge two vibrant yet seemingly disconnected research frontiers: macroscopic finite-strain solid mechanics and quantum-like topological physics. Here, we demonstrate that the classical elastic surface instability of a deformed hyperelastic manifold is not merely a mechanical bifurcation, but fundamentally a topological phase transition. By incorporating Lie group metric evolution into a generalized Stroh formalism, we map the highly nonlinear geometric frustration onto an algebraic surface impedance matrix $\mathbf{H}$. For a semi-infinite hyperelastic half-space under finite compression, we analytically map the system to a one-dimensional Dirac Hamiltonian, where the macroscopic mechanical stretch acts as a tunable knob for the Dirac mass. We reveal that the onset of surface wrinkles marks a topological transition from a trivial to a non-trivial phase characterized by a quantized step in the winding number, naturally giving rise to a robust, macroscopically localized zero-energy edge state. This fundamental linkage unifies macroscopic symmetry breaking with the topological paradigm, opening a new theoretical pathway for programmable smart soft matter.

math-ph

Active control of higher-order topological corner states in a piezoelectric elastic plate

Different from the traditional bulk-edge correspondence principle, the discovery of higher-order topological states has generated widespread interest. In a second-order, two-dimensional elastic wave topological insulator, the fluctuation information can be confined to the corners, with the state being topologically protected. In order to better apply topological corner states, this paper designs a two-dimensional elastic plate with adjustable topological corner states by means of piezoelectric control capability. By selectively connecting negative capacitance circuits to piezoelectric sheets on the honeycomb elastic plate, the energy band can be flipped. The topological corner states at the 2π/3 corner were observed at the boundary of two different topological phase structures in the finite lattice with finite element software. The strong robustness of the topological corner states was verified by setting up defective control groups at the corner. In addition, the topological corner states of this piezoelectric elastic plate are discussed accordingly in terms of their tunability in frequency and position. The piezoelectric elastic plate is expected to provide a reference for the design of elastic wave local control and energy harvesting devices due to its adjustable topological corner states, which facilitate the application of topological corner states in practice.

physics.app-ph

A novel buckling pattern in periodically porous elastomers with applications to elastic wave regulations

This paper proposes a new metamaterial structure consisting of a periodically porous elastomer with pore coatings. This design enables us to engender finite deformation by a contactless load. As a case study, we apply thermal load to the pore coating and carry out a finite element analysis to probe instabilities and the associated phononic properties. It turns out that a novel buckling mode, preserving the nature of surface wrinkling in tubular structures, can be induced under a plane-strain setup, and a smaller size of the unit cell is attained compared to the counterpart of traditional buckled profile in soft porous elastomers. In particular, this buckling pattern is able to produce several bandgaps in different frequency ranges as the macroscopic mean strain increases. We further introduce a metallic core as local resonator, and the updated metamaterial allows a low-frequency bandgap, the bandgap width of which can be estimated by a simplified theoretical model. As more free parameters are involved in the structure, we perform a detailed parametric study to elucidate the influences of the modulus ratio between coating and matrix, the porosity, the core radius, and the macroscopic mean strain on the buckling initiation and the evolution of bandgap. Remarkably, a stiffer surface coating is prone to enhance the stability of the structure, which is contrary to existing results in film/substrate bilayers. It is expected that the current study could shed light on new insight into pattern formation and wave manipulation in porous elastomers.

cond-mat.soft

Inflation-induced aneurysm formation and evolution in graded cylindrical tubes of arbitrary thickness

We study the initiation and evolution of aneurysmal morphology in a pressurized soft tube where the elastic modulus is non-uniform in the radial direction. The primary deformation prior to instability is characterized within the framework of nonlinear elasticity for a general material constitution and a generic modulus gradient. To unravel the influence of modulus gradient on aneurysm formation, we employ the incompressible Gent model and select three representative modulus gradients, including a linear, an exponential, and a sinusoidal function. In particular, the sinusoidal distribution can be used to model actual artery structure. In addition, two prototypical loading conditions are considered, namely, either the resultant axial force or the axial length can be fixed. Based on an explicit bifurcation condition in terms of the internal pressure and the resultant axial force for aneurysm formation or localized bulging, an exhaustive theoretical analysis on bulge initiation is carried out and the effect of geometric and material parameters and modulus gradient on the critical stretch generating localized bulging is revealed. It turns out that the modulus mismatch, as well as the position of maximum modulus, can dramatically affect the onset of localized bulging. Then we analytically elucidate the influence of modulus gradient on bulge propagation and conduct a finite element analysis of bulge evolution based on a robust finite element model established in Abaqus by UHYPER subroutine coding. Interestingly, it is found that a sinusoidally distributed modulus has negligible influence on the critical stretch of bulge initiation, the deformation process of bugle growth, and the maximum size of a bulge. The current analysis can provide useful insight into the biological evolution of human artery and into localized instabilities in graded structures.

cond-mat.soft