Geometrically frustrated magnets provide an ideal platform for exploring the interplay between lattice geometry and spin degrees of freedom. Here, we investigate the interactions between lattice and spin via thermal-transport measurements on the triangular sawtooth-lattice olivine magnet ${\mathrm{Fe}}_2{\mathrm{SiSe}}_4$, which exhibits successive magnetic transitions at $T_1=110\mathrm{K}$ (antiferromagnetic) and $T_2=50\mathrm{K}$ (ferrimagnetic). Although phonons dominate the thermal conductivity, its temperature dependence displays a pronounced double-peak structure arising from spin–phonon coupling. In the intermediate temperature range between $T_1$ and $T_2$, resonant scattering of phonons by magnetic excitations around 5 meV produces a broad maximum around 60 K. Below $T_2$, the resonant spin–phonon scattering is strongly suppressed, leading to a rapid increase in thermal conductivity upon cooling and a pronounced low-temperature peak near 11 K, characteristic of heat transport governed by conventional phonon scattering mechanisms. Notably, this low-temperature peak is enhanced by a factor of $\sim 5$ compared to the broad maximum at higher temperatures. These results demonstrate the strong sensitivity of thermal transport to spin–lattice interactions and highlight spin-phonon scattering as an effective mechanism for tailoring thermal conductivity in geometrically frustrated magnets.

Understanding how quantum systems evolve from integrable to fully chaotic behavior remains a central open problem in physics. In this work, we show that the Yukawa-Sachdev-Ye-Kitaev (YSYK) model is a particularly rich testbed to address this question. This model extends the paradigmatic SYK model of many-body chaos and holography by introducing boson-mediated random all-to-all fermionic interactions. Using spectral and dynamical chaos markers, we perform a comprehensive numerical characterization tailored to the mesoscopic regime relevant for quantum simulation. We show that, at finite size, the YSYK model interpolates between single-particle and many-body chaos, with the interaction strength acting as a tunable control parameter interpolating between ${\mathrm{SYK}}_2$ and ${\mathrm{SYK}}_4$ behavior. We introduce a framework enabling direct and quantitative comparison with these benchmark models, and we uncover prethermalization plateaus as well as delayed and incomplete scrambling appearing in an intermediate regime that weakly breaks integrability. We further propose a feasible optical-cavity realization of the YSYK model using ultracold atoms, opening the door to studies beyond the capacities of numerical investigations. Our results establish the YSYK model as a benchmark platform connecting single-particle and many-body chaos, and they provide a quantitative reference point for future quantum simulations.

Red-shifted near-infrared emissions in ${\mathrm{Cr}}^{3+}$-activated oxides at high concentrations are commonly attributed to ${\mathrm{Cr}}^{3+}\text{−}{\mathrm{Cr}}^{3+}$ ion pairs, yet whether these redshifts arise from exchange-coupled pairs or from locally perturbed isolated ions remains unclear. To address this issue, we establish a first-principles framework that quantitatively determines the ground-state exchange coupling constant $J$ and the emission redshift of the ${\mathrm{Cr}}^{3+}$ pairs in strong crystal-field environments. Our calculations reveal that face-sharing octahedral pairs can exhibit redshifts up to $\sim 0.2\mathrm{eV}$, whereas edge-sharing and corner-sharing pairs show only moderate ($<0.15\mathrm{eV}$) and small ($<0.07\mathrm{eV}$) shifts. We further find that excited-state electron-phonon coupling acts synergistically with magnetic exchange, significantly influencing both the Stokes shift and the redshift amplitude. This unified picture clarifies the microscopic origin of pair-related near-infrared emissions and provides a practical criterion for distinguishing genuine ${\mathrm{Cr}}^{3+}\text{−}{\mathrm{Cr}}^{3+}$ ion-pair centers from other luminescent defects in ${\mathrm{Cr}}^{3+}$-activated oxides.

We develop a self-consistent first-principles framework for determining the screened Coulomb interaction strength $\left(U\right)$ based on constrained dynamical mean-field theory (cDMFT). Unlike conventional approaches, this method incorporates essential vertex corrections within the same embedded-DMFT formalism used for the electronic structure calculation. Using the cDMFT-derived interaction strengths as input to embedded DMFT yields spectral functions in excellent agreement with photoemission experiments across a wide range of materials, spanning $3d$ to $5d$ transition-metal compounds, including correlated metals, Mott insulators, altermagnets, and unconventional superconductors. This unified many-body framework establishes a systematic first-principles route for determining interaction strengths in correlated materials and substantially enhances the predictive power of $\mathrm{DFT}+\mathrm{DMFT}$ and its extensions.

We observed the fractional quantum Hall effect at a total filling factor of $7/3$ in the Hall resistance, accompanied by a single minimum in longitudinal magnetoresistance in uncoupled, bilayer electron gases formed in GaAs double quantum well systems. When the density of the top electron gas is varied, the total $7/3$ $(1+4/3)$ state can be tuned such that while the Hall plateau value essentially remains unchanged, the associated longitudinal magnetoresistance develops into a double minimum. When Zeeman energy is introduced by tilting the applied magnetic field, the two minima respond differently; one remains essentially unchanged, while the other deepens, consistent with the differing spin dependences of the integer and fractional gaps. Our results demonstrate that the detailed evolution of the $7/3$ plateau probes layer-resolved incompressibility, interlayer charge redistribution, and spin-dependent gap behavior in a nontunneling bilayer system.

Recent imaging experiments show a surprisingly robust regime of liquid-solid phase coexistence in a two-dimensional electron system near the quantum melting/freezing transition, with the two phases mixed in mesoscopic domains. Strikingly, the experiments find no noticeable difference in electron density between the liquid and solid domains, which is at odds with both microemulsion scenarios and scenarios in which phase coexistence is driven by fluctuations of a long-ranged disorder potential. Here, we show that such phase coexistence without density difference can be induced by random fluctuations of a short-ranged disorder potential. We further show that disorder tends to stabilize the Wigner crystal phase to higher densities, which is also consistent with the experiments.

We compute the $E_2$ pages of the momentum-space and real-space Atiyah-Hirzebruch spectral sequence (AHSS) for topological crystalline insulators and superconductors up to three spatial dimensions, using cell decompositions such that any group element that fixes a cell setwise also fixes it pointwise. We provide a detailed description of the implementation for computing the $E_2$ pages of AHSS. Under a physically reasonable assumption, we enumerate all possible $K$-groups that are compatible with the $E_2$ pages for both momentum and real-space AHSS. As a result, we determined the $K$-groups for approximately 59% of symmetry settings in three spatial dimensions.

Solving excited states is a challenging task for interacting systems. For one-dimensional critical systems, however, excited states can be directly accessed from the eigenvectors of the local effective Hamiltonian that is constructed from the ground state obtained by variational matrix product state (MPS) optimization. Despite its numerical success, the theoretical mechanism underlying this method has remained largely unexplored. In this work, we provide a conformal field theory (CFT) perspective that helps elucidate this connection. The key insight is that this construction effectively uses a truncated basis of ground-state Schmidt vectors to represent excited states, where the contribution of each Schmidt vector can be expressed as a CFT correlation function and shown to decay with increasing Schmidt index. The CFT analysis further predicts an entanglement-spectrum transition of excited states as the ratio of the subsystem size to the total system size is varied. Our numerical results support this picture and demonstrate a reorganization of the entanglement spectrum into distinct conformal towers as this ratio changes.

We present magnetization and dilatometry measurements on the honeycomb cobaltate ${\mathrm{Na}}_3{\mathrm{Co}}_2{\mathrm{SbO}}_6$ and map out its detailed field-temperature phase diagram down to sub-Kelvin temperatures. Our data for in-plane magnetic fields show a strongly anisotropic $c^{*}$-axis lattice response, which is dominated by the variation of Co–O–Co bond angles according to ab initio calculations. At $T=0.4\mathrm{K}$, the magnetization $M\left(B\right)$ exhibits steplike features that are also highly anisotropic. In the case of $B\parallel b$, a small hysteresis observed around the second field-induced magnetic transition ($B_{c2}$) indicates its first-order character, whereas the apparent divergence of the magnetic Grüneisen parameter at $B_{c2}$ is suppressed upon cooling and signals the absence of quantum critical behavior upon entering the field-polarized state. None of our thermodynamic measurements provide evidence for a field-induced quantum spin-liquid state near or above $B_{c2}$.

A lens, a device transforming propagation directions in an organized fashion, is one of the fundamental tools for wave manipulation. Spin wave, the collective excitation of ordered magnetizations, stands out as a promising candidate for future energy-saving information technologies. Here we propose theoretically and verify by micromagnetic simulations, that an antiferromagnetic skyrmion naturally serves as a lens for spin wave, when the Dzyaloshinskii-Moriya strength exceeds a threshold. The underlying mechanism is the spin wave deflection caused by Dzyaloshinskii-Moriya interaction, a mechanism that is ordinarily overshadowed by the magnetic topology.

Several physical phenomena in superconductors, such as helical superconductivity and the diode effect, rely on breaking time-reversal symmetry. This symmetry breaking is usually accounted for via the Lifshitz invariant, a contribution to the free energy which is linear in the phase gradient of the order parameter. In dispersive single-band superconductors with conventional pairing, the Lifshitz invariant can be computed from the asymmetries of the spectrum near the Fermi surface. We show that in multiband superconductors, the quantum geometry also contributes to the Lifshitz invariant, and this is the dominant contribution when the low-energy bands are flat. We also analogously demonstrate quantum-geometry-driven commensurate-incommensurate transitions in charge and pair density waves.

We have performed in situ time-resolved x-ray diffraction at $\simeq 100$ GPa on laser-shocked ${\mathrm{CaSiO}}_3$ glass to investigate the glass-to-crystal transition. At this extreme pressure, we observe the ultrafast crystallization of the ${\mathrm{CaSiO}}_3$ perovskite structure from the compressed amorphous phase, with a typical nucleation time of 1.69 $\pm$ 0.10 ns and a final grain size of $\approx 20$ nm. The grain size temporal evolution suggests a diffusion-controlled transformation. Moreover, the observed concomitant explosive grain growth together with the release wave arrival into shocked ${\mathrm{CaSiO}}_3$ also suggests a role of the release in the nucleation process.

In this work, making use of time-resolved in situ joule heating of a two-dimensional electron gas (2DEG) in the Corbino geometry, we report bulk thermal conductance measurements for the $\nu =5/2$ and $\nu =7/3$ fractional quantum Hall (FQH) states for electron temperatures ranging from 20 to 150 mK. We compare our findings with a recent study by Melcer et al. [Nature (London) 625, 489 (2024)] that observed a finite bulk thermal conductivity ${\kappa }_{xx}$ in FQH states. In spite of the large size difference and the vastly different experimental schemes used to extract ${\kappa }_{xx}$, we find in large part that both experiments yield similar results and conclude that the bulk of FQH states thermally conducts and violate the Wiedemann-Franz law by a wide margin. Differences between both studies pertaining to particle-hole symmetry in the vicinity of the 5/2 FQH state are discussed in terms of the underlying many-body wave function forming the ground state whereby in one case an edge contribution was present and then subtracted, and in the other no edge transport was ever present due to the Corbino geometry used.

Demonstration of a nontrivial result of quasiparticle exchange (or braiding) is usually considered the definitive proof of a topological phase with non-Abelian excitations, such as Majorana bound states (MBSs). However, in finite systems with disorder and smooth potential variations, the MBSs are imperfect in the sense that they are not fully isolated in space and can, to a varying degree, resemble conventional fermions. The main goal of this work is to reveal the braiding properties of isolated MBSs, regular fermions, and anything in between. We start from an experimentally attractive braiding protocol and find a way to compensate for the undesired splitting of the ground-state degeneracy which occurs during the protocol for imperfect MBSs. This leads to a braiding outcome that depends on the degree of MBS isolation but remains robust and non-Abelian except in the perfect fermion limit. Our protocol could be implemented in different platforms with non-Abelian excitations, including quantum-dot-based minimal Kitaev chains.

We systematically investigate the transport and photoluminescence measurements of a high-mobility two-dimensional electron gas in a GaAs/AlGaAs quantum well under magnetic fields $B$. By tuning the laser excitation power $P_{\mathrm{ex}}$, transitional patterns of the singlet and triplet (negative charged) trions occur in the high-$B$ regime: The two branches of singlet trions $X_s^{-}$ dominate at low $P_{\mathrm{ex}}$ $(<1$ $\mathrm{W}/{\mathrm{mm}}^2)$, and six more triplet $X_t^{-}$ branches emerge at high $P_{\mathrm{ex}}$ $(\sim 1-10$ $\mathrm{W}/{\mathrm{mm}}^2)$. At extremely high laser $P_{\mathrm{ex}}$ $(>100$ $\mathrm{W}/{\mathrm{mm}}^2)$ and at fixed $B$ fields, robust Fano resonance features are accompanied by the Gaussian resonance centered at $X_s^{-}$, which illustrates dark and bright trions. Therefore, a very high laser excitation (or electromagnetic field) becomes an efficient tool to probe dark trions. In addition, discontinuity and splitting features occur at fillings $\nu =2,4,6$, and the abrupt drops at high odd fillings factors ($\nu \sim 5,7,9$, etc.) originate from spin-resolved many-body interactions.

In the field of condensed matter physics, extensive efforts have been put into the exploration of the anomalous Hall effect (AHE) since the dominance of Berry phase curvature and spin-orbit-coupling-mediated scattering provides a powerful probe for topological order in quantum materials, a key pursuit for developing next-generation dissipationless spintronic devices. Nonetheless, the underlying mechanisms of the AHE in the low conductive dirty regime (longitudinal conductivity ${\sigma }_{xx}<{10}^4{\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$) remain insufficiently understood because of the difficulty in preparing pure ferromagnetic metals with low conductivity. To address this, we utilized the technology of low-energy cluster beam deposition to control the structural disorder and successfully prepared ferromagnetic nanogranular CoFe films with a low conductive metallic state, which allow us to systematically investigate the AHE of pure ferromagnetic metals in the dirty regime. Our results reveal a nonmonotonic evolution of anomalous Hall conductivity ${\sigma }_{\mathrm{AHE}}$ with increasing cluster size. The possible dominant mechanism is the intrinsic contribution derived from the scaling relationship between ${\sigma }_{xx}$ and ${\sigma }_{\mathrm{AHE}}$ notwithstanding the presence of the extrinsic skew scattering. More importantly, ${\sigma }_{\mathrm{AHE}}$ not only falls within the dirty regime but also is consistent with the widely established scaling exponent of ${\sigma }_{\mathrm{AHE}}\propto {\sigma }_{xx}^{1.6}$, which indicates that the degenerative AHE arises from the damping of the intrinsic contribution. In this work, we show the potential of cluster-assembled engineering in the exploration of the quantum transport properties for future electronics devices.

van der Waals (vdW) heterostructures of two-dimensional (2D) materials have become a rich playground for the exploration of correlated quantum phases, and recent studies have begun to probe their nonequilibrium dynamics under femtosecond laser excitation. In a time-resolved experiment, optical excitation of the multilayer structure can lead not only to rich dynamic responses from the target layers, such as moiré interfaces, but also to additional device functionality from the layer degree of freedom. Here, we investigate optical excitation in a prototypical moiré device of dual-gated twisted ${\mathrm{WSe}}_2$ bilayers, with few-layer graphite gates and hexagonal boron nitride spacers. We establish an ultrafast photodoping mechanism in the moiré bilayer from photothermionic emission of the graphite gates. Using transient reflectance experiments, we reveal photoinduced hole injection evidenced by: (i) a shift of gate voltages at which optical signatures of correlated insulators are observed, (ii) a persistent optical signature indicative of charge diffusion at microsecond timescales and local charge buildup from pulse-to-pulse accumulation, and (iii) photoinduced absorption due likely to transient formation of correlated insulators. We further demonstrate that the injected holes can be selectively controlled by tuning the excitation energy, fluence, and gate bias.

Accurate modeling of magnetism is pivotal for elucidating the microscopic origins of magnetic phenomena in functional materials. However, for a specified class of materials, such as random dilute ferromagnets or alloys, the reliance on simplifying assumptions, such as single-ion anisotropy, limits the accuracy of existing spin models. In such systems, there is a significant probability of the formation of nearest-neighbor magnetic ion pairs or higher-order clusters, whose presence breaks the local symmetry of otherwise isolated magnetic species. Here, we introduce the concept of pair-induced uniaxial anisotropy and demonstrate how nearby atoms influence each other's anisotropic behavior. This effect is investigated in the dilute magnetic semiconductor ${\mathrm{Ga}}_{1-x}{\mathrm{Mn}}_x\mathrm{N}$, by means of density-functional theory calculations. The inclusion of pair anisotropy in the atomistic spin simulations significantly improves the agreement between simulated and experimental magnetization curves, in contrast to models that consider only single-ion anisotropy.

Phononic frequency combs (PFCs) typically require nonlinear elastic media, limiting their frequency range and stability. Here, we propose a transformative approach to generate PFCs in purely linear elastic media by harnessing the magnon nonlinearities, offering a new paradigm for frequency comb physics. By tuning the magnon-phonon coupling confined in a magnetic disk of a vortex state into the strong coupling regime, we demonstrate an efficient nonlinearity transfer from magnons to phonons. This mechanism is able to produce GHz-range PFCs with comb spacing set by the vortex core's gyration frequency. Full micromagnetic simulations verify our theoretical predictions, confirming robust comb formation. The approach overcomes the sub-MHz constraints of conventional PFCs, enabling applications in high-precision metrology, nanoscale sensing, and quantum technologies. Our findings also deepen the understanding of the nonlinear dynamics in hybrid magnon-phonon systems and provide a versatile platform for exploring frequency combs in diverse physical systems.

Despite being predicted almost a century ago as the excitations of the spin-1/2 antiferromagnetic chain, Bethe strings were overshadowed by the more dominant multi-spinon-pair excitations and were only observed recently. Here we confirm their existence in the quasi-one-dimensional quantum antiferromagnet ${\mathrm{BaCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$ using a magnetic field to separate them from the spinons. We find excellent quantitative agreement over an extended field range between these experimental results and our theoretical predictions based on the algebraic Bethe ansatz formalism. This work proves the existence of Bethe strings (multimagnon bound states) up to length-3 in ${\mathrm{BaCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$.