We study the interplay between a Coulomb impurity and quasiholes in a fractional quantum Hall (FQH) state at finite temperatures. While a repulsive impurity can pin a quasihole and stabilize the FQH state, an attractive impurity cannot bind quasiholes. We demonstrate that at finite temperatures, a quasihole can be thermally ionized from a repulsive impurity, resulting in a thermal ionization crossover. We propose an experimental setup using exciton sensing to detect such a thermal ionization of quasiholes.

We develop a theoretical framework based on the dynamical projective operatorial approach (DPOA) to study the time-resolved and angle-resolved photoemission spectroscopy (TR-ARPES) of pumped excitonic systems. Including Coulomb electron-electron interactions at the Hartree-Fock level, our formalism captures the formation of excitonic bound states under the application of pump pulses. Considering a prototypical two-dimensional two-band semiconductor, we analyze the equilibrium phase diagram, which shows the expected transition from a semiconducting to an excitonic-insulator phase as the Coulomb interaction strength or its range increases. Out of equilibrium, we find that when the pump frequency is resonant with an excitonic mode, coherent oscillations of the excitonic order parameter persist after the pump pulse subsides, and they give rise to clear Floquet sidebands in the TR-ARPES spectrum. These exciton-field-induced sidebands are distinct from those originating from the pump laser field. We also identify band-resonance-induced sidebands arising from residual coherences at momenta where the band gap is resonant with the pump frequency. Finally, we analyze the local Coulomb interaction limit. Our results corroborate recent experimental observations of exciton-field-induced Floquet-like sidebands and establish DPOA as an efficient and accurate method for simulating ultrafast phenomena in interacting electron systems.

Scalar spin chirality (SSC) underlies a variety of Berry-phase-driven transport phenomena in noncoplanar magnets. ${\mathrm{Mn}}_4\mathrm{N}$ is a unique ferrimagnetic system in which both collinear and noncoplanar magnetic configurations have been reported at different lattice parameters, featuring vanishing and finite SSC, respectively. However, the microscopic mechanism governing the competition between these magnetic states and the associated modulation of SSC remains unclear. This issue is particularly important for ${\mathrm{Mn}}_4\mathrm{N}$ because its high magnetic ordering temperature $(T_{\mathrm{N}}=740\mathrm{K})$ provides an attractive platform for exploring chiral magnetic states and their associated topological functionalities at elevated temperatures. Here, using first-principles calculations, we investigate the strain-driven evolution of the magnetic ground state and SSC in ${\mathrm{Mn}}_4\mathrm{N}$ and uncover the microscopic origin of the collinear-to-noncoplanar magnetic transition. We demonstrate that tensile strain continuously stabilizes the noncoplanar configuration and enhances SSC, as quantified by the magnitude of the chirality-order vector. Orbital-resolved crystal orbital Hamilton population and charge-density-difference analyses reveal that strain selectively weakens the Mn3c-N hybridization while preserving direct Mn3c-Mn3c interactions, leading simultaneously to the activation of the Mn3c in-plane magnetic moment and the suppression of N-mediated ferromagnetic superexchange between nearest-neighbor Mn3c atoms. This bond-selective electronic response governs the magnetic ground state and consequently controls the emergence and enhancement of SSC in ${\mathrm{Mn}}_4\mathrm{N}$. Our work establishes bond selectivity as an effective strategy for engineering SSC in high-temperature ferrimagnetic materials.

The role of spin-phonon interaction in affecting the magnetic behavior of two-dimensional ferromagnets remains an open issue. We investigate ultrafast magnetization dynamics in two-dimensional ferromagnetic ${\mathrm{Fe}}_3{\mathrm{GaTe}}_2$ at room temperature by employing time-resolved magneto-optical Kerr effect and reflectivity spectroscopy. A two-step demagnetization process is observed. By utilizing a generalized temperature model in conjunction with first-principles electron-phonon coupling calculations, we present a self-consistent phenomenological framework demonstrating that the fast demagnetization stage (<1 ps) and the subsequent slower stage are, respectively, governed by energy relaxation into distinct high-frequency and low-frequency phonon baths. Compared to 0.05-T applied magnetic field, a stronger magnetic field of 0.4 T accelerates both processes, decreasing the time constants from 0.8 to 0.5 ps (fast component) and from 24 to 20 ps (slow component). The magnetic field accelerates both processes by enhancing spin-flip scattering via modulated different phonon-spin coupling. Moreover, magnetization recovery shortens by 65% (1760 to 620 ps) with magnetic field, attributed to domain-wall motion and thermal diffusion. Theoretical analysis and dynamic simulations confirm that these transient behaviors originate from the Elliott-Yafet phonon-assisted spin-flip mechanism. Our findings elucidate microscopic spin-energy transfer mechanisms in two-dimensional (2D) magnets and advance prospects for ultrafast spintronic devices.

We study the emergence of superconductivity in the one-band Hubbard model using the spin-rotation-invariant Kotliar-Ruckenstein slave-boson (SB) approach. Motivated by its intrinsically renormalized mean-field ground state, we construct an effective pairing vertex from dynamical fluctuations about the saddle point. Solving the anisotropic, frequency-dependent gap equation on the square lattice, we map the pairing instabilities across doping, interaction, temperature, and real-frequency gap structure that qualitatively match experimental cuprate observations. This framework merges strong-correlation SB-type renormalizations with random-phase-approximation-type pairing transparency, providing a scalable route to modeling multiorbital superconductivity at strong coupling.

In the correlated kagome metal ${\mathrm{CsCr}}_3{\mathrm{Sb}}_5$, the interplay among lattice, charge, and spin degrees of freedom governs its rich quantum phases, yet remains poorly understood. Here, we present a comprehensive investigation of these couplings through temperature- and magnetic-field-dependent polarized Raman spectroscopy. Our polarization-resolved measurements unambiguously identify a structural phase transition at $T^{*}\approx 55\mathrm{K}$, establishing a low-temperature orthorhombic phase. A striking reduction in phonon linewidths below $T^{*}$ reveals the suppression of electron-phonon coupling (EPC) coinciding with the opening of a charge density wave gap. Remarkably, upon suppression of EPC, a robust spin-phonon coupling (SPC) emerges in the magnetically ordered state, as evidenced by anomalous phonon broadening and pronounced magnetic field modulation of phonon intensities. These findings not only clarify the low-temperature structure of ${\mathrm{CsCr}}_3{\mathrm{Sb}}_5$ but also establish a clear boundary between the EPC-dominated and SPC-active phases, offering key spectroscopic evidence for understanding the unconventional physics in this strongly correlated kagome metal.

We introduce a random matrix framework for studying statistical-mechanical lattice systems through spectral observables. Equilibrium configurations sampled from a Boltzmann measure are mapped to matrix ensembles whose covariance structure is inherited from the spatial correlations of the underlying model. This construction maps real-space correlation functions to a momentum-space variance profile, providing a direct bridge between statistical-mechanical correlations and correlated random matrix ensembles. We derive this variance profile in finite-correlation-length and critical regimes, and compute spectral moments within a Wick-contraction expansion. A complementary self-consistent description of the bulk density is developed using the resolvent formalism. These analytical methods are benchmarked against Monte Carlo data for the two-dimensional Ising model and three-dimensional Edwards-Anderson spin glasses. In both cases, the spectra evolve from the semicircle law at high temperature to model-dependent critical forms reflecting the structure of correlations. The framework, therefore, provides a quantitative spectral route to probing collective behavior in ordered and disordered statistical systems, while also defining a class of physically motivated correlated random matrix ensembles.

Two-dimensional magnetism in triangular lattices has already shown a potential for hosting exotic magnetic states. Control of these magnetic states, both in terms of magnetic properties and in terms of charge doping would be the next step. This makes materials which combine triangular lattice magnetic layers with layers hosting interesting structural or electronic properties particularly useful. ${\mathrm{PrCd}}_3{\mathrm{P}}_3$, studied in this work, is one of a family of materials where triangular lattice layers of magnetic rare earth ions alternate with semiconducting hexagonal CdP layers. Using Raman scattering spectroscopy we uncover a structural instability in the CdP layers, associated with a soft mode behavior of a phonon in these layers. Raman scattering detects crystal electric field excitations, and confirms a singlet ground state for ${\mathrm{Pr}}^{3+}$ and splitting of the doublet levels as a result of the structural instability in CdP layers. While ${\mathrm{Pr}}^{3+}$ is nonmagnetic in ${\mathrm{PrCd}}_3{\mathrm{P}}_3$ we speculate that this family of materials can realize control of the magnetic rare earth layer via control of the coupled nonmagnetic CdP layer. Additionally, we expect that these materials could become ferroelectric or multiferroic under strain that would relieve frustration.

We investigate how local magnetic correlations evolve when the classical pyrochlore spin ice ${\mathrm{Ho}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$ is transformed into the partially disordered stuffed compound ${\mathrm{Ho}}_2{\mathrm{TiO}}_5$. Neutron scattering measurements were analyzed using real space magnetic pair distribution function, reciprocal space reverse Monte Carlo, and half-polarized neutron powder diffraction methods to connect the average crystal structure with local magnetic correlations. Both compounds retain long-range $Fd\overline{3}m$ symmetry, but in ${\mathrm{Ho}}_2{\mathrm{TiO}}_5$ the average structure does not fully capture the local Ho–O, Ti–O, and O–O bond-length disorder associated with partial Ho/Ti occupancy. Despite this disorder, half-polarized neutron powder diffraction shows that the Ho moments retain local $\langle 111\rangle$ Ising anisotropy and form spin-in/spin-out configurations on the tetrahedral network. In ${\mathrm{Ho}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$, real- and reciprocal-space analyses show a nearly ideal 2-in/2-out spin ice state at 0.3 K, with $\sim 95\%$ of tetrahedra satisfying the ice rule, followed by progressive thermal disordering on warming. In ${\mathrm{Ho}}_2{\mathrm{TiO}}_5$, most tetrahedra are magnetically incomplete because some tetrahedral vertices are occupied by nonmagnetic Ti rather than Ho; nevertheless, the dominant incomplete configurations are 2-in/1-out and 1-in/2-out, which are locally compatible with the ice rule if the missing Ho spin is restored. ${\mathrm{Ho}}_2{\mathrm{TiO}}_5$ is therefore a vacancy-disrupted spin ice in which the local $\langle 111\rangle$ Ising character and short-range spin-in/spin-out correlations persist on a topologically incomplete magnetic network, while collective ice-rule correlations are strongly disrupted.

Ab initio calculations suggest that the robust ferroelectricity of ${\mathrm{HfO}}_2$ at reduced dimensions arises from a unique mode coupling in which an antipolar mode stabilizes a polar distortion. Based on these insights, Landau-Devonshire energy models have been proposed using these lattice modes as order parameters. However, most existing models remain limited to simplified one-dimensional descriptions because of the high computational cost of ab initio calculations and the limitations of conventional Landau polynomials. In this study, we constructed a three-dimensional Landau-Devonshire potential for ${\mathrm{HfO}}_2$ by employing tetragonal, antipolar, and polar modes as coupled order parameters using machine-learning techniques. We generated a large-scale dataset of energies over a three-dimensional structural space, with the computational cost drastically reduced through the use of machine-learning interatomic potentials. Using this dataset, we trained a neural network (NN) to learn the complex relationship between the order parameters and the energy. The trained NN captured the characteristic coupling behavior in which antipolar modes induce the polar mode. Furthermore, we extended this NN-based Landau potential to a position-dependent functional for phase-field modeling. Using this framework, we show that, in thin films, the critical strain required for the onset of spontaneous polarization increases, while the coercive field for polarization switching decreases, as the polarization magnitude is reduced by surface effects. This study presents the on-demand construction of phase-field models using modern machine-learning techniques, thereby enabling multiscale analysis of complex ferroelectric phenomena.

Charge-density-wave (CDW) order in ${\mathit{R}\mathrm{Pt}}_2{\mathrm{Si}}_2$ $(\mathit{R}=\mathrm{Pr}, \mathrm{Nd})$ develops through a complex sequence of structural and electronic transitions. Using atomic pair distribution function analysis and large-scale structural modeling, we show that both compounds exhibit local lattice distortions dominated by locally static Pt displacements already present at room temperature, prior to the onset of long-range CDW order. Upon cooling, these distortions become progressively correlated and evolve into superstructures characterized by alternating short and long Pt-Pt distances, forming lattice modulations along different crystallographic directions. Our results suggest a predominantly order-disorder character of the higher-temperature second-order transitions, whereas the lower-temperature first-order transitions involve a significant additional displacive component, superimposed on the preexisting Pt displacements, and further reorganization of the CDW state. These findings establish a structural connection between intrinsic lattice instabilities and the development of long-range CDW order in ${\mathrm{PrPt}}_2{\mathrm{Si}}_2$ and ${\mathrm{NdPt}}_2{\mathrm{Si}}_2$.

We investigate the effect of interfacial exchange coupling on the broadband ferromagnetic resonance (FMR) response of thin-film ${\mathrm{IrMn}}_3/\mathrm{NiFe}$ bilayers, focusing on the evolution of effective magnetization $\left(M_{\mathrm{eff}}\right)$ and rotatable anisotropy field $\left(H_{\mathrm{ra}}\right)$ as a function of ${\mathrm{IrMn}}_3$ layer thickness $\left(t_{\mathrm{AF}}\right)$ from 0 to 4.5 nm, encompassing the paramagnetic to antiferromagnetic (AF) phase transition of ${\mathrm{IrMn}}_3$. Our results reveal a $\sim 4\%$ enhancement in $M_{\mathrm{eff}}$ upon formation of AF ordering in ${\mathrm{IrMn}}_3$, without a corresponding change in the volumetric magnetization of NiFe. Theoretical modeling indicates that this effect arises from the hybridization between the standard FMR mode of NiFe and the fundamental mode of the ${\mathrm{IrMn}}_3$ layer, which is activated by interfacial exchange coupling. Because the fundamental mode frequency of ${\mathrm{IrMn}}_3$ lies far above the GHz FMR range, this hybrid mode penetrates the ${\mathrm{IrMn}}_3$ layer as an evanescent excitation, making $M_{\mathrm{eff}}$ predominantly sensitive to the interfacial exchange energy rather than to the bulk AF parameters. A control calculation in which the AF moments are held fixed produces only a resonance-field shift and no enhancement of $M_{\mathrm{eff}}$, demonstrating within the model that the observed increase requires a dynamical AF response. Our results establish $M_{\mathrm{eff}}$ as a valuable tool for probing AF spin excitations, given that it is a more phenomenon-specific indicator in comparison to other FMR parameters that produce homogeneous resonance field shifts.

Understanding the formation and dynamics of two-exciton bound states (BSs) is crucial for harnessing multiexciton phenomena and designing next-generation organic semiconductor materials. While various mechanisms such as intermolecular exciton-exciton interactions or multilevel intramolecular configurations can generate these BSs, a fundamental understanding of their underlying lattice dynamics remains a key challenge. Within this context, the Merrifield exciton model stands out as a premier framework for capturing the intricate quantum mixing between single-site doubly excited states and two-particle scattering continuum. In this work, by constructing a set of exact two-exciton Bloch states and applying a plane-wave ansatz to treat the resulting inhomogeneous tridiagonal matrices, we provide a complete, rigorous solution to the two-exciton problem in a finite-size Merrifield chain. We analytically map the parameter regions that support two-exciton BSs, proving that at most two distinct types of BSs can emerge, located either above or below the scattering continuum. Furthermore, we provide a quantitative interpretation of how these two types of BSs evolve as a function of the total wave number within the whole Brillouin zone. The obtained closed-form expressions for the eigenenergies and wave functions offer valuable benchmarks for exploring exciton dynamics and optical responses in related molecular aggregates.

Nodal line semimetals (NLSMs) are topological materials characterized by one-dimensional band crossings in momentum space, which typically carry a Berry phase quantized to integer multiples of $\pi$. Here, we extend the conventional paradigm to a class of NLSMs in which the Berry phase can take arbitrary fractional or even irrational multiples of $\pi$. This nonquantized Berry phase leads to a splitting of Landau levels when a magnetic field is applied parallel to the nodal ring, an effect that can be detected via Shubnikov–de Haas oscillations in the magnetoconductivity. Despite the absence of a quantized topological invariant, drumheadlike surface states with weak dispersion persist at open boundaries. Notably, two identical surface states localize on the same boundary, in contrast to conventional NLSMs, where they reside on opposite boundaries. A systematic symmetry analysis shows that such NLSMs can be realized in a broad range of magnetic space groups. Our work opens an avenue for exploring NLSMs beyond the conventional framework of a quantized Berry phase.

We formulate a quantum master equation for the many-particle density matrix of electrons propagating through a single-mode conductor, combining elastic scattering by disorder with time-resolved projective measurements that monitor the outcome of scattering events. For noninteracting electrons the charge transfer statistics is governed entirely by the single-particle sector of Fock space, which allows us to resum the exponentially many measurement outcomes into a master equation of dephasing-channel form. The full counting statistics of transmitted electrons has a binomial distribution function, whose mean $\mathcal{T}$ and variance $\mathcal{T}(1-\mathcal{T})$ determine the conductance and shot noise power, respectively. Monitoring suppresses the phase coherence responsible for one-dimensional localization: The decay with conductor length $L$ of the typical transmission probability crosses over at $L\simeq {\ell }_{\varphi }$ from the exponential $e^{-L/\xi }$ (with localization length $\xi$) to the Ohmic $1/L$ decay. Numerical solution of the master equation gives, for weak monitoring, a logarithmic dependence ${\ell }_{\varphi }\simeq \xi ln(v_{\mathrm{F}}{\tau }_{\varphi }/\xi )$ of the coherence length ${\ell }_{\varphi }$ on the mean time ${\tau }_{\varphi }$ between measurements.

Plasmonic surface lattice resonances (SLRs), characterized by low radiative loss, play an important role in nanophotonics and optical metasurfaces. However, conventional coupled dipole approximation (CDA) treatments are restricted to deterministic homogeneous excitation, resulting in limited flexibility and restricted degrees of freedom. Here, by combining CDA with singular-value decomposition, we establish a unified theoretical framework that reformulates SLRs as a physical eigenproblem connecting two distinct Hilbert spaces. This approach yields orthogonal basis sets for arbitrary lattice geometries, and provides a general description of plasmonic lattice response under arbitrary excitation, thereby naturally enabling the joint optimization of incident fields and structural geometries. This work provides deeper insight into light-lattice interactions and paves the way for designing advanced SLR-based applications.

A parallel in-plane magnetic field could, in principle, distinguish between two competing physical scenarios for the experimentally observed density-tuned 2D metal-insulator transition (where decreasing the carrier density leads to a crossover from an effective metal to an effective insulator): Wigner crystallization or Anderson localization. Importantly, the observation of such a density-driven metal-insulator transition alone does not uniquely determine the microscopic nature of the insulating state. Since the main scattering mechanism in 2D doped semiconductors arises from screened random charged impurities and screening in turn depends on the electronic density of states, the in-plane magnetic field could distinguish between the two by decreasing screening through spin polarization and this enhances the effective critical density for Anderson localization compared with Wigner crystallization. We give the general theory and provide results for the quantitative magnitudes of the spin polarization effect on the transition density by focusing on two recent experiments [Z. Ge et al., Nature (London) 654, 902 (2026), T. Han et al., arXiv:2604.00113], noting that the critical density may actually decrease if the dominant scattering is by short-ranged defects instead of long-ranged charged impurities. The difference between the two cases arises from whether spin polarization dominates screening (enhanced critical density) or the Fermi surface (suppressed critical density).

Altermagnetism has been widely explored in three- and two-dimensional crystals, but its one-dimensional realization remains largely unexplored. Here, we propose an altermagnetic nanotube formed by rolling a two-dimensional altermagnet, which converts symmetry-enforced directional spin anisotropy in momentum space into spin-chirality locking in the screw-symmetric geometry. Unlike curvature-induced magnetization in bent films, the nanotube remains compensated and produces no net magnetization. Two reciprocal effects emerge: (i) Spin-selective injection drives a helical current whose handedness is fixed by the spin, yielding opposite-sign axial magnetic fields; and (ii) a time-varying axial flux generates a circumferential Faraday field that drives equal and opposite axial charge currents in the two fixed spin channels, yielding a charge-neutral spin-channel current in the open-circuit weak spin-orbit coupling limit. Explicit first-principles calculations of the relaxed ${\mathrm{V}}_2{\mathrm{Se}}_2\mathrm{O}$ nanotube reveal spin-resolved helical ${\left|\psi \right|}^2$ modulations near both band edges, while a parent-monolayer Wannier-Boltzmann calculation quantifies the energy-dependent spin-odd transverse response and corresponding ideal thin-wall field scale.