Papers

Viscoelastic fluid flows over micro-textured surfaces - densely covered by slender protrusions like cilia lining the body airways or villi covering the intestinal epithelium - underpin essential biological processes including transport, mixing, and absorption. Despite their ubiquity, the dynamics generated by the interplay between fluid elasticity and these complex geometries remain largely unexplored. Here we combine fully resolved numerical simulations with microfluidic experiments to reveal the flow dynamics established above dense arrays of microscopic pillars (canopies) immersed in the low-Reynolds-number flow of a viscoelastic liquid. We observe that the flow above the canopy tips spontaneously develops elastic turbulence. Remarkably, the chaotic state coexists with elastic waves emerging from the coupling between fluid elasticity and the heterogeneous shear induced by the canopy geometry. These ordered fluid motions persist across a broad range of flow conditions and canopy configurations. Our results demonstrate that coherent wave propagation and elastic turbulence are complementary manifestations of viscoelastic fluid flow. Beyond their fundamental significance, these mechanisms have broad implications for transport in biological and engineered environments, and reveal how structured geometries can harness the spontaneous dynamics of viscoelastic liquids to manipulate complex flows.

Electric and magnetic control of transport properties at atomic interfaces is central to the development of next generation electronics and spintronics. Van der Waals multiferroics materials that simultaneously host dielectric and magnetic orders down to the monolayer limit offer a promising platform for such interfacial control, yet the realization of electronic functionalities that exploit the unique attributes of van der Waals multiferroics has largely remained elusive. Here, we realize a van der Waals heterostructure comprising graphene and the multiferroic CuCrP2S6, enabling gate-switchable magnetoelectric transport in graphene, mediated by the multiferroic layer. The charge-neutrality resistance peak of graphene exhibits pronounced hysteresis arising from polarization flip in the multiferroic state. Application of an in-plane magnetic field shifts this peak in a polarization-dependent manner, revealing magnetic-field-induced polarization modulation a direct signature of the magnetoelectric effect. Furthermore, cooling the device under an applied electric field enables domain control of the multiferroic order, allowing reversible switching of the interfacial magnetoelectric transport. These results provide the first demonstration of interfacial magnetoelectric transport in a vdW heterostructure, and establish a pathway for engineering two-dimensional van der Waals interfaces for functional device applications.

Time-resolved terahertz (THz) spectroscopy is used to probe polaron formation in CeO$_2$. The ultrafast THz photoconductivity is dominated by contributions from large hole and small electron polarons. Delocalized large hole polarons are formed on a $820 \pm 50$ fs time scale and are of Fröhlich type, with optical conductivity well described by a simple Drude model and a transient hole mobility of $100$ cm$^2$/Vs. Small electron polarons form via localized coupling to Ce lattice sites, revealed by reduction in the lattice Born effective charge causing a transient phonon softening. These results establish the dual polaron nature of CeO$_2$ and provide a basis for understanding charge transfer dynamics in metal oxide photocatalysts.

Granular particles typically feature contact friction, which gives rise to various nontrivial properties of granular materials. In this work, we investigate the linear stability of static packings composed of frictional spheres, whose interactions are modeled using the discrete element method. We discuss a key difficulty in properly modeling static friction and address the problem of identifying rattlers. We also explore the spectrum of the energy matrix, which governs the linear viscoelastic response of the system. The intermediate- and high-frequency regimes of the spectrum remain qualitatively independent of both the friction coefficient and the packing fraction.

We develop a quantum-electrodynamical theory for universal tuning of spontaneous emission and Förster resonance energy transfer (FRET) in a material-agnostic conductor-dielectric-conductor heterostructure. The platform consists of a dielectric spacer of thickness $W$ bounded by two gate-tunable two-dimensional conductors. The only microscopic input from the surrounding materials is the transverse-magnetic and transverse-electric reflection amplitudes $r_{\TM/\TE}(q_\rho,\omega)$ of the two sheets. Starting from the QED photon propagator, we derive the retarded Maxwell dyadic, the vacuum/Hadamard field propagator, and the time-ordered Feynman propagator in the same geometry. The spontaneous-emission rate is controlled by the local vacuum spectral density, while FRET is controlled by the nonlocal retarded/advanced product $\obG_{\text R}(\bx_D,\bx_A;\omega_D)\Im\,\balpha_A(\omega_D)\obG_{\text A}(\bx_A,\bx_D;\omega_D)$. In the transparent limit $r_{\TM}\to 0$, the near-field FRET rate recovers the bulk $x_\rho^{-6}$ law. In the Dirichlet/PEC branch $r_{\TM}\to -1$, the gapless transverse mode is removed and the donor-acceptor coupling acquires a Bessel-$K$ envelope, giving an exponentially screened FRET rate $\Gamma_{D\to A}\propto\exp(-2\pi x_\rho/W)$ at large lateral separation. In the opposite Neumann/PMC-like branch $r_{\TM}\to 1^{-}$, a nearly gapless transverse mode survives and produces a wide quasi-two-dimensional logarithmic propagator, enhancing the nonlocal electromagnetic coupling over a gate-programmable range $x_{\rho,*}\sim W/(1-r_{\TM})$. For graphene-Er implementations, the same retarded Green tensor also separates dissipative on-shell Er-to-graphene decay, governed by its absorptive part, from dispersive virtual-plasmon-mediated Er-Er coupling, governed by its reactive part; a plasmonic band gap can suppress the former while retaining the latter.

We report experimental diacovery of superconductivity (SC) in tellurium (Te) polyhydride. The compound was synthesized at high pressure and high temperature conditions using a diamond anvil cell combined with a laser heating system. Subsequent in situ transport measurements at high pressures, performed as a function of temperature and applied magnetic field, revealed a superconducting transition with a critical temperature Tc about 91 K at 263 GPa. The superconducting phase is assigned to TeH4 with characterized face shared TeH12 cage forming quasi molecular H2 units based on synchrotron x-ray diffraction experiments. Analysis of the SC behavior at magnetic fields yielded a Ginzburg Landau (GL) coherence length of approximately 54 angstroms. Tellurium polyhydride thus becomes another chalcogen polyhydride superconductor in addition to the landmark discovery of the first polyhydride high Tc SC SH3.

We demonstrate an attosecond transient absorption spectroscopy (ATAS) scheme for reconstructing strain tensors in two-dimensional materials. Using strained graphene as a prototype system, we show that the fishbone structures in ATAS serve as distinctive spectral fingerprints of strain, where strain-induced shifts and splittings of van Hove singularities encode the magnitude and orientation of the strain tensor, respectively. By combining density-matrix simulations with analytical modeling, we establish a direct mapping between transient absorption spectra and strain tensors, enabling accurate retrieval of lattice deformation from ultrafast electronic responses. Our work introduces an attosecond spectroscopic paradigm for ultrafast strain metrology, where electronic fingerprints replace conventional structural probes for sensing lattice deformation in quantum materials.

Dissimilar joining of NiTi to Ti-6Al-4V (Ti-64) is limited by brittle Ti2Ni formation and degradation of NiTi functionality. A two-step transient liquid phase (TLP) route was developed in which a refractory NbZrW diffusion barrier converts the incompatible couple into two independently bondable interfaces. The barrier plays a different role for each alloy: a reactive substrate for NiTi, dissolving to form a Ti-rich Ni-Ti-Nb liquid that infiltrates its own grain boundaries and is terminated by selective Ti absorption into the barrier; and an inert substrate for Ti-64, joined through contact melting of a sacrificial Cu foil. Both interfaces are fully dense and free of continuous intermetallic layers. In tension, joints spanning both interfaces began transforming at 350 MPa, exhibited a stress plateau to 2.5 global strain (consistent with stress-induced transformation of the NiTi half of the gauge) and failed beyond the plateau at 380-410 MPa. Five load-unload cycles to 460 MPa showed stable superelastic loops with minor ratcheting. These results demonstrate that a diffusion barrier enables dissimilar TLP joining of otherwise incompatible alloys.

We applied a dynamic fluctuation measurement method to liquid water-methanol mixtures over a wide range of compositions and temperatures. This method, which we developed in recent years, combines ultrasonic and inelastic X-ray scattering techniques to detect mesoscopic-level fluctuations - that is, the degree of heterogeneity - in liquids using sound waves. As a result, it was found that dynamic fluctuations exist across a wide range of compositions and temperatures, including pure substances (water and methanol). Furthermore, in the low-methanol composition range (approximately 20% mol or less), the strength of dynamic fluctuation increased toward lower compositions and lower temperatures, suggesting that the origin of the fluctuation lies in the low temperature (supercooled) region of water alone. Conversely, this indicates that in the range below 20% methanol, fluctuations in water alone are dominant rather than the mixed effects of water and methanol. We performed similar dynamic fluctuation measurements on water-ethanol and water-glycerol mixtures at room temperature. We found that dynamic fluctuations exist universally across the entire composition range, and confirmed an increase in the strength of dynamic fluctuations toward lower compositions in the regions approximately below 15% and below 20%, respectively. This revealed that the phenomenon is not unique to methanol systems but is a common behavior shared by water-alcohol mixtures. It has long been known that water-alcohol mixtures exhibit various thermodynamic anomalies, but the mechanisms behind them have not yet been fully elucidated. The present results are expected to provide a new direction for discussion on this issue.

In three-electrode electrochemical impedance spectroscopy (EIS), the impedance/capacitance response of the working electrode (WE) is measured relative to the reference electrode (RE), whereas the current required by potentiostatic control flows between the WE and the counter electrode (CE). Under classical three-electrode operation, the measured WE-RE response should therefore be independent of the properties of the electrode used as the CE, provided that conventional electrochemical and instrumental artifacts are negligible. Here, we test this expectation in cells containing nanostructured electrodes TiO2 + rGO and examine the results within a framework motivated by quantum discord to describe effective interelectrode correlations. We used dummy-cell measurements, a two-electrode bar-bar control, comparisons between Pt and bar CEs, a dummy circuit introduced into the CE branch, and CE ensemble comparisons to distinguish additive circuit behavior from CE-dependent behavior specific to the three-electrode configuration. In these experiments, the measured three-electrode capacitance response depends on CE, an effect that is not reproduced by the dummy-circuit controls examined. These findings identify a macroscopic CE-dependent capacitance response that departs from the tested classical expectation and is compatible with an effective interelectrode-correlation framework motivated by quantum discord, although the capacitance evidence alone does not constitute a direct measurement of quantum discord.

Powder X-ray diffraction (XRD) is central to materials characterization, yet reliable end-to-end automation remains challenging. An XRD agent must interpret diffraction evidence, operate refinement software, manage coupled parameters in a defensible order, and distinguish numerical improvement from physical validity. In this paper, we propose AutoXRD, an autonomous large language model (LLM) agent framework that organizes powder-XRD analysis as stepwise refinement, grounds actions in observed evidence, and applies deterministic crystallographic and physical checks before accepting results. We further introduce XRDBench with two complementary tracks. XRDBench-QA contains 100 bounded diagnostic tasks that isolate scientific reasoning and decision-making, whereas XRDBench-E2E contains 34 executable workflows that test whether agents can compose these capabilities into complete analyses requiring file inspection, crystallographic-software execution, iterative refinement, evidence preservation, and reporting. We evaluate ten recent LLMs across 1,340 model–task runs. Models average only 57.8 out of 100, falling from 61.9 on XRDBench-QA to 53.7 on XRDBench-E2E. They perform best on refinement-history assessment and result acceptance, but remain substantially weaker on refinement-action selection, phase quantification, indexing, and Rietveld refinement. GPT-5.6 Sol achieves the highest overall score of 81.1, GPT-5.6 Terra the highest XRDBench-E2E point estimate of 81.0, and GPT-5.6 Luna the best score–cost trade-off. Ablations show that all six AutoXRD components consistently improve performance, supporting the framework design. Finally, execution-trace analysis reveals recurring failures in coupled-parameter control, quantitative reasoning, evidence preservation, and workflow termination, motivating stronger scientific constraints, uncertainty-aware decisions, and more efficient planning.

Multistable mechanical systems can store and release elastic energy through snap-through instabilities, but controlling transition pathways between stable states remains challenging when multiple routes are accessible. Here, we introduce a two-mass von Mises truss as a general model for studying pathway selection governed by coupled saddle-node bifurcations. The system consists of two coupled snap-through units with geometric imperfections, giving rise to four stable configurations: a fully inverted state, a fully natural state, and two intermediate mixed states. We show that the coupling stiffness reorganizes the quasi-static bifurcation structure and selects among three transition pathways under release: sequential snapping through one mixed state, direct cooperative snapping, or sequential snapping through the other mixed state. Using pseudo-arclength continuation, we track the relevant saddle-node bifurcations and identify the parameter regimes associated with each quasi-static pathway. We then demonstrate that dynamic bifurcation delay provides an additional rate-dependent mechanism for pathway selection. Even when the quasi-static bifurcation structure favours a unique sequential pathway, finite-rate loading delays snap-through beyond the corresponding static saddle-node points and can reorder the snapping sequence of the two units. A local reduction of the coupled dynamics near each saddle-node yields normal forms with coupling-dependent critical points and coefficients. The resulting theory identifies distinct rate-dependent delay laws in the inertia-dominated and overdamped regimes and predicts the critical rate at which the snapping order reverses. These results establish a general mechanics framework for tuning transition pathways in multistable systems through elastic coupling and loading-rate control.

Vacancy-ordered perovskites R2MX6 combine a rigid inorganic framework with a molecular A-site cation, but how the cation dynamics couples to the lattice phonons under external perturbation remains largely unexplored. The librational motion of NH4+ in (NH4)2SnCl6 is strictly Raman-silent by symmetry, which is why it has been probed almost exclusively by neutron scattering, NMR and NQR. We show that it is nevertheless accessible to Raman spectroscopy, through the renormalization it imposes on the allowed [SnCl6]2- modes. Combining single-crystal X-ray diffraction with Raman scattering between 10 and 300 K and up to 10.1 GPa, we find that the average cubic structure varies smoothly with no anomaly, while below ~100 K the [SnCl6]2- modes acquire a libron-phonon renormalization (E_eff ~ 4.7 meV) and a symmetry-selective line asymmetry, and the N-H stretch passes through a minimum near 120 K (E_eff ~ 9.3 meV); both track the classical-to-quantum crossover of the ammonium rotor. The two effective energies lie below the bare librational transition of 13.4 meV measured by neutrons, as expected for a self-energy scale. The ammonium linewidths, by contrast, are governed by pure dephasing rather than by anharmonic decay and carry no crossover signature. Under pressure the octahedral modes stiffen smoothly, whereas the cavity responds twice: the translational F2g mode of NH4+ gains Raman intensity above 1.3 GPa, and the N-H stretch inverts its pressure slope near 1.7 GPa, with no change of space group and full recovery on decompression. The rigid octahedral framework is thus essentially decoupled from a dynamically active NH4+ subsystem that carries the response to both perturbations, offering a route to tune cation-phonon coupling independently of the octahedral network.

The chemical potentials of charged multi-component mixtures are central to electrolyte thermodynamics, but remain difficult to compute from atomistic simulations. The S0 method enables computing chemical potentials of mixtures from equilibrium molecular dynamics simulations. Here we extend the S0 method to charged mixtures by combining the composition-space framework developed in Part I: Neutral Multi-component Mixtures with a Coulombic treatment of the small-wavenumber limits of static structure factors. This approach separates thermodynamically relevant neutral composition fluctuations from forbidden macroscopic charge fluctuations, and further accounts for charge-neutrality constraints. We use the method to compute the chemical potentials of multiple-halide aqueous salt solutions, elucidating the ion-specific thermodynamic effects. We also calculate the mixing free energies of molten salt mixtures, demonstrating the importance of correctly describing long-wavelength electrostatic correlations.

In recent years, kirigami metamaterials have been widely studied and applied in science and engineering. While various two- and three-dimensional kirigami design methods have been developed, most of them are only applicable to a limited class of kirigami structures. In this work, we develop a unified framework for kirigami design that encompasses a wide range of 2D-to-2D, 2D-to-3D, and 3D-to-3D shape-morphing effects, as well as additional geometric and physical properties such as compact reconfigurability and rigid deployability. In particular, by reformulating the design task as a length-based constrained optimization problem and solving it simultaneously for multiple target states of the kirigami structure, our unified design framework enables greater design flexibility and stronger theoretical support. Experimental results with a wide range of shape-morphing effects are presented to demonstrate the effectiveness of our framework. We further present a rigorous theoretical analysis of several key aspects of kirigami design, covering inertia transposition, aspect-ratio law, and angle defects, thereby elucidating important design rules and limitations. Altogether, our work paves a new way for the design of shape-morphing mechanical metamaterials.

The interplay between twist-angle engineering and unconventional magnetism provides a powerful new route to control quantum phenomena. We theoretically investigate a heterostructure comprising a $d$-wave superconductor proximitized by a two-dimensional $d$-wave altermagnet. We reveal that the momentum-space mismatch between the superconducting gap nodes and the altermagnetic spin-splitting nodes generates a robust, twist-tunable odd-frequency spin-triplet pairing. Consequently, the macroscopic electromagnetic response of the system can be tuned from a conventional diamagnetic Meissner state to an anomalous paramagnetic Meissner effect driven entirely by the interfacial twist angle. For a $d_{x^2-y^2}$ altermagnet, the paramagnetic response is maximized at perfect alignment ($\phi=0$) and completely suppressed at a maximal twist of $\phi=\pi/4$, while a $d_{xy}$ altermagnet exhibits the exact complementary behavior. Our results establish twisted altermagnetic heterostructures as a versatile platform for engineering odd-frequency pairing and macroscopic superconducting phases.

Disordered dynamical systems comprising many interacting units, from ecological communities to neural circuits, are ubiquitous, and understanding how connectivity shapes their collective behavior is a central theoretical challenge. One long-recognized feature of neural circuits is local connectivity balance, in which the excitatory and inhibitory weights converging onto each unit approximately cancel. Although local connectivity balance has been proposed to serve functions such as gating incoming signals, its effect on collective network dynamics remains unclear. Here we analytically study randomly connected recurrent networks with varying degrees of local connectivity balance. We show that this balance leaves the connectivity spectrum unchanged yet drastically reshapes the dynamics in a manner that depends critically on the single-unit nonlinearity. Local balance suppresses unbounded growth of the network state and stabilizes network dynamics when the activation function scales linearly or faster, whereas it drives the network into chaos when the activation function is sub-linear or saturating. Importantly, these effects vanish for odd activation functions, which are commonly assumed in previous work. We further find that, for saturating nonlinearities, the effective dimension of the dynamics varies nonmonotonically with the degree of balance. We show that all these phenomena arise from a unifying mechanism: the suppression of a self-generated feedback input by local connectivity balance. Our results identify local connectivity balance as a previously overlooked control parameter for collective dynamics in realistic disordered networks.

Fractal geometries provide a distinctive platform for controlling quantum interference, topology, and localization. We investigate the Su–Schrieffer–Heeger (SSH) model constructed on the Koch curve, where a triangular geometry enables additional same-sublattice hoppings that break chiral symmetry and modify the conventional topological behavior captured by a real-space local marker. Destructive interference within the triangular units produces a highly degenerate flat level at $E=-t$. Although this level originates from the local geometry, its degeneracy and spectral weight are controlled by the self-similar connectivity of the Koch curve. The hierarchy reduces the number of independent flat states and reorganizes the spectrum into an intricate distribution of energy levels. Our results reveal complementary roles for local triangular interference and global fractal connectivity in shaping the electronic properties of geometrically modified SSH chains.

The observation that the coherence lengths in cuprate superconductors are extremely small motivated us to search for its real-space structure by examining the consequence of hole-doping in CuO4 units in cuprates. We analyzed aggregates of hole-doped CuO4 units that phase-separate from hole-doped CuO2 layers in terms of their segregation-pressure indices defined in this work. Our search suggests that each d-wave Cooper pair is an antiferromagnetically coupled spin dimer protected in an antiferromagnetic hole dimer (AHD), and that the antiferromagnetic chains of AHDs provide channels through which such spin dimers can move collectively without perturbation. Based on these suggestions and their implications, we examined the causes for several seemingly puzzling observations on cuprate superconductors to find that they are naturally explained by the suggestions.

We report the structural and vibrational properties of the prototypical 4$f$-filled nonmagnetic member LuN of the lanthanide nitrides, LnN, with elastic and inelastic neutron scattering data at $4$~K. We find a peak in the generalized density of states which, through input from a DFT+$U$ computation, we ascribe to a van Hove singularity on the fourfold-degenerate $L$-face of the Brillouin zone. This work advances the understanding of phonon dynamics in LnN beyond the $\Gamma$-point.

We investigate directed transport in a one-dimensional Brownian flashing ratchet with a piecewise-linear asymmetric periodic potential. Numerical solutions of the Fokker–Planck equation and Brownian dynamics simulations reveal a nonmonotonic dependence of the stationary current on the switching frequency, with a resonant maximum whose position depends on the potential asymmetry $\delta$ and barrier height $\Delta$. For moderate asymmetry, $|\delta|<0.5$, the current obeys a scaling form that separates the dependence on the potential parameters from a common frequency dependence, resulting in a data collapse upon appropriate scaling of the current and frequency. The current amplitude varies linearly with $\delta$, while the resonance frequency follows $\nu(\delta,\Delta)=\nu_0(\Delta)/ [1-b_0\, \delta^2]$. We interpret the resulting $(1-\delta^2)^{-1}$ scaling in terms of coupled relaxation along the two branches of the asymmetric potential, which provides a physical basis for the observed dependence of the resonant frequency on the potential asymmetry.

We report the first numerical examination of symmetric mass generation (SMG) for domain-wall fermions. Our simulation on a two-dimensional Euclidean lattice computes the path-integral of the Fidkowski-Kitaev Majorana chain with two boundaries, corresponding to the two (physical and mirror) walls. We demonstrate by evaluating the lattice Dirac operator eigenvalue spectrum that the local four-Fermi interaction selectively gaps the edge fermions on the mirror wall while leaving the physical wall intact. We further identify a characteristic signature of SMG in the path-integral: the gap of the Dirac operator opens along the imaginary axis of the complex spectrum, in contrast to the standard mass shift in the real direction. The conventional hybrid Monte Carlo algorithm remains practical with reweighting the complex phase of the Pfaffian, which is found to be remarkably small throughout the simulation. These results provide a practical nonperturbative framework for interaction-induced mirror-fermion decoupling of lattice domain-wall fermions.

We prove that the stationary density fluctuation field of the one-dimensional weakly asymmetric simple inclusion process converges to the energy solution of the stochastic Burgers equation. The key technical ingredient is a second-order Boltzmann-Gibbs principle tailored to the microscopic current. As a consequence, we also obtain Ornstein-Uhlenbeck fluctuations for the symmetric inclusion process in a weakly condensing regime, a result of independent interest.

We determine the exact entanglement structure of the conditional state obtained by measuring $m$ corresponding rungs ($m\leq N/2$) in two identical copies of an arbitrary half-filled free fermion Gaussian state and post-selecting the same normalized single-fermion state ($|\psi\rangle = u|10\rangle+v|01\rangle$, where 0 and 1 denote the fermion occupancy on each sites) on each rung. For $m<N/2$, the conditional wavefunction generally depends on the initial state. Nevertheless, whenever the selected outcome has nonzero probability, the state on the unmeasured sites remains Gaussian and factorizes exactly into $N-m$ different orthogonal modes including $m$ inter-copy entangling modes and $N-2m$ spectator modes localized in one copy. Consequently, the entanglement entropy between the unmeasured parts of the two copies is $S=m h_2(|v|^2)$, independent of the initial state, where $h_2(x)=-x\ln x-(1-x)\ln(1-x)$. The success probability is given by $P_m=\det C_L\det(I_m-C_L)=\det(C_{LR}C_{RL})$, determined solely by the initial correlations and independent of ($u$,$v$). Equal-weight Bell post-selection serves as a special case that achieves the maximal entanglement swapping.

We study the topological structure of the quantum phase diagram of gapped systems by identifying the noncontractibility of loops, so-called $S^1$-families, within the gapped phase diagram in which many-body Hamiltonians can have nontrivial ground-state degeneracy. We manifest the role of symmetries in such $S^1$-family classifications by the exotic symmetry interplay: (i) nontrivial mixed anomalies, (ii) semi-direct product relation between the spontaneously broken and the unbroken symmetries, and (iii) symmetry with noninvertible operators. We find that such structures lead to the novel $S^1$-family classifications inaccessible by earlier classifications based on “independent” symmetries. Furthermore, we construct lattice realizations of these $S^1$-families and explicitly demonstrate their novel algebraic structures.

Several next-generation fission reactor designs employ molten salts such as FLiBe (2LiF-BeF$_2$), with some concepts using fuel dissolved directly in the salt. During operation, fission products such as cesium will accumulate in the salt mixture, potentially leading to an evolution of the thermophysical properties underpinned by the atomic structure. To understand the structural perturbations in FLiBe with 5 mol% CsF, we conducted X-ray and neutron diffraction measurements, refined empirical potential structure refinement (EPSR) models against the experimental data, and compared the resulting structure with neural network molecular dynamics (NNMD) simulations. Comparisons of the EPSR and NNMD structures distinguishes features constrained by the scattering data from those that remain model dependent. The new Cs-bearing correlations account for the changes in the total structure factor and pair-distribution function, while the FLiBe correlations remain minimally altered. We find that Cs slightly disrupts the intermediate-range fluoroberyllate network, increasing the fraction of free fluorine ions, while the local coordination remains largely unchanged. The Cs ions within FLiBe cluster extensively, with BeF$_4^{2-}$ tetrahedra bridging neighboring cesium environments. In contrast to the minor structural perturbations in the liquid, the addition of 5 mol% CsF suppressed the formation of the crystalline Li2BeF4 phase at room temperature, with the phase appearing only above 180C upon heating. These experimentally constrained structural features provide a benchmark for atomistic models used to predict the behavior and properties of fission-product-containing FLiBe.

In the whole space of low spatial dimensions, namely $d \leq 2$, we study the minimizers of an energy functional with an attractive cubic nonlinearity and a repulsive quintic nonlinearity, which describes a quantum Bose gas with a two-body attraction and a three-body repulsion. We prove the existence of minimizers at fixed effective statistics parameter. In the limit of a large effective statistics parameter of the mass-critical nonlinearity (with respect to the kinetic energy), we derive an effective Thomas-Fermi-like model for the homogeneous Bose gas. We also consider other limit regimes depending on the mass-critical nonlinearity.

We consider a homogeneous Bose gas composed of $N$ identical bosons occupying an infinite two-dimensional space. This gas exhibits both an attractive two-body interaction and a repulsive three-body interaction. Via the intermediate Hartree theory, we rigorously derive the homogeneous cubic-quintic nonlinear Schroedinger functional as the mean-field limit of the model. Our investigation focuses on the system's behavior in relation to the two-body interaction.

We investigate the behavior of a homogeneous one-dimensional Bose gas composed of $N$ identical bosons experiencing attractive two-body and repulsive three-body interactions. Utilizing intermediate Hartree theory, we rigorously derive the homogeneous cubic-quintic nonlinear Schrödinger functional as the mean-field limit of the many-body Hamiltonian. Particular attention is given to the impact of the repulsive three-body term on ground state energy estimates and mass concentration properties

Rhombohedral multilayer graphene hosts a distinctive low-energy electronic structure in which strong Coulomb interactions and nontrivial quantum geometry intertwine to generate exotic quantum states. Recent experiments reported signatures of chiral superconductivity in electron-doped rhombohedral multilayer graphene within the spin- and valley-polarized regime. Here we map the normal-state fermiology surrounding chiral superconductivity in rhombohedral pentalayer graphene. Quantum oscillation measurements reveal an electrically controlled Lifshitz transition between a simply-connected circular quarter-metal Fermi surface and an annular quarter-metal Fermi surface. The Lifshitz boundary itself shifts with perpendicular magnetic field, consistent with the strongly momentum-dependent orbital magnetic moment of the low-energy band. Approaching the transition from either side, the electron effective mass becomes strongly enhanced, implying the formation of a nearly dispersionless band bottom and a strongly reduced kinetic-energy scale. This singular electronic structure produces a regime of exceptionally strong instability in which chiral superconductivity competes with Wigner crystalline phases and reentrant quantum Hall states. In particular, two superconducting regions with signatures of orbital time-reversal-symmetry breaking lie on opposite sides of the Lifshitz boundary and have comparable transition temperatures, yet the annular-side state is suppressed by a substantially smaller perpendicular magnetic field. Our calculation finds comparable chiral pairing tendencies on the two parent Fermi surfaces while producing a much lower orbital-Zeeman pair-breaking scale and an additional finite-momentum pairing tendency for the annular state. These results identify Fermi-surface topology as a key control parameter for chiral superconductivity in rhombohedral graphene.