The study of hydrogen bonding symmetry in lower mantle water-bearing minerals is scientifically critical for understanding the water cycle in the deep Earth, the stability and physical properties of minerals, and the electrical conductivity structure of the Earth's interior. We report classical molecular dynamics simulations of Phase D $\left({\mathrm{MgSi}}_2{\mathrm{O}}_6{\mathrm{H}}_2\right)$, a dense hydrous magnesium silicate, using a deep-learning-optimized interatomic potential, demonstrating spontaneous hydrogen bonding symmetrization emergence at 33.7 GPa under hydrostatic compression. Additionally, within a specific pressure-temperature range, we observed abnormal phenomena in bulk modulus and lattice constant ratio. Further analysis indicates that these anomalies are actually caused by the phase transition from asymmetric hydrogen-bonded state 1 (AHB1) to AHB2 and the proton-disordering transition, decoupled from hydrogen bonding symmetry. This study provides insight into the structure and dynamics of the Earth's interior, as well as the distribution and occurrence state of hydrogen within the Earth.

Fading ergodicity provides a theoretical framework for understanding deviations from the eigenstate thermalization hypothesis (ETH) near ergodicity-breaking transitions. In this work we demonstrate that the position of the ergodicity-breaking critical point in the quantum sun model coincides with the peak of the maximally divergent fidelity susceptibility. We further extend our analysis to the energy-resolved ergodicity-breaking transition associated with the many-body mobility edge. Specifically, we show that fidelity susceptibilities at energies away from the middle of the spectrum exhibit a divergent peak near the mobility edge. We argue that fading ergodicity provides a simple and accurate description of the ETH breakdown in the quantum sun model, which is accompanied with the emergence of a peak in fidelity susceptibility and the onset of maximal chaos at the ergodicity-breaking critical point.

Floquet dynamics temporally deforms the band structure of the system, called Floquet engineering, under a strong optical field. Although a single resonant pulse simultaneously drives both exciton and Floquet dynamics, the Floquet engineering during exciton generation remains unexplored. We examine the Floquet engineering of excitons by a theoretical simulation of the time-resolved and angle-resolved photoemission spectroscopy in monolayer ${\mathrm{MoS}}_2$. Our finding reveals that the exciton experiences nontrivial engineering inducing a distinct asymmetry in the development of spectral splitting with the time delay and pump intensity, which are underlain by the electron-hole interaction inherent in the exciton binding.

We suggest the first method for direct ab initio calculation of adiabatic magnons in complex collinear magnets. The method is based on the density-functional-theory (DFT) calculation under two different constraints: one constraint governs the change of the magnetization with respect to the ground state, and the other is the symmetry constraint responsible for the value of the magnon wave vector. The advantages of the suggested method with respect to the usual approach of mapping of the electron system on the Heisenberg Hamiltonian of interacting magnetic moments are discussed. The performance of the method is demonstrated by the application to an altermagnet MnTe. The altermagnetism introduced as a concept in 2022 is at present an area of highly intensive research. The characteristic feature of altermagnets is the spin splitting of the electron states in reciprocal k space. Among the discovered properties of the altermagnets is the chirality splitting of the magnons in wave vector q space. We suggest an appoach to the study of the symmetry aspects of magnon chirality splitting. We show that both the chirality splitting of the magnons and the altermagnetic spin splitting of the electron states, though very different in their physical nature, have identical patterns in the corresponding wave vector spaces. Since the altermagnetism of MnTe is the consequence of the presence of the Te atoms, adequate attention is devoted to the symmetry analysis and calculation results for the Te moments induced in the magnon states. In the calculations, each magnon is characterized by its own electron band structure. We investigate the transformation of the electron structure in the transition of the material from the collinear ground state to noncollinear magnon states. We show the connection between the properties of magnon band structures and the chirality properties of magnons. In the investigation of the chirality splitting as well as in both the formulation and the application of our method, an important role play the aspects of generalized symmetry based on the application of the spin-space groups. The symmetry framework connects in one coherent picture different parts of the consideration: (i) the generalized translational symmetry of the magnons as a crucial condition for their efficient ab initio calculation, (ii) altermagnetic spin splitting of the electron states in the ground state, and (iii) chirality splitting and band structures of the magnon excitations.

Altermagnets, a recently discovered class of magnets, uniquely merge the zero net magnetization of antiferromagnets with the spin splitting characteristic of ferromagnets. By harnessing the advantages of both—such as enabling anomalous transport without stray fields and supporting ultrafast spin dynamics—altermagnets offer exciting prospects for advancing dissipation-free spintronics and spin-caloritronics. In this study, we conduct detailed symmetry analysis and advanced first-principles calculations to investigate the intrinsic anomalous Hall, anomalous Nernst, and anomalous thermal Hall effects in the two-dimensional topological altermagnet ${\mathrm{V}}_2{\mathrm{Te}}_2\mathrm{O}$. In the nonrelativistic limit, monolayer ${\mathrm{V}}_2{\mathrm{Te}}_2\mathrm{O}$ exhibits $d$-wave spin splitting and hosts two spin-polarized nodal loops near the edge centers of the Brillouin zone. Upon incorporating spin-orbit coupling, the nonzero tensor elements of all three anomalous transport conductivities are identified using magnetic group theory. Depending on the orientation of the Néel vector, the nodal loops become partially or fully gapped. The curvature of the nodal loops significantly enhances the anomalous Nernst conductivity at room temperature while maintaining the validity of the anomalous Wiedemann-Franz law up to 200 K. These findings position ${\mathrm{V}}_2{\mathrm{Te}}_2\mathrm{O}$ as a compelling two-dimensional altermagnetic platform for exploring the interplay between altermagnetism, topological nodal structures, and anomalous transport properties, paving the way for advancements in altermagnetic spintronics and spin-caloritronics.

The large anomalous Hall conductivity (AHC) of the ${\mathrm{Fe}}_3(\mathrm{Ge},\mathrm{Ga}){\mathrm{Te}}_2$ compounds has attracted considerable attention. Here, we expose the intrinsic nature of the AHC in ${\mathrm{Fe}}_3{\mathrm{GaTe}}_2$ crystals characterized by high conductivities, which show disorder-independent AHC with a pronounced value ${\sigma }_{xy}^{\text{c}}\approx$ 420 ${\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$. In the low-conductivity regime, we observe the scaling relation ${\sigma }_{xy}\propto {\sigma }_{xx}^{1.6}$, which crosses over to ${\sigma }_{xy}\simeq {\sigma }_{xy}^{\text{c}}$ as ${\sigma }_{xx}$ increases. Disorder in low-conductivity crystals is confirmed by the broadening of a first-order transition between ferromagnetism and the ferrimagnetic ground state. Through density functional theory (DFT) calculations, we reveal that the dominant sources of Berry curvature are located a few hundred meV below the Fermi energy around the $\mathrm{\Gamma }$ point. Therefore, ${\mathrm{Fe}}_3{\mathrm{GaTe}}_2$ clearly exposes the disorder-induced crossover among distinct AHC regimes, previously inferred from measurements on different ferromagnets located on either side of the crossover region.

We investigate how spatiotemporal spin polarized current can lead to terahertz frequency excitations in noncollinear antiferromagnets. By solving the Landau-Lifshitz-Gilbert equation numerically for noncollinear antiferromagnets, we show that the magnon frequency spectrum exhibits standing spin wave modes and depends on the thickness of ${\mathrm{Mn}}_3\mathrm{Ge}$ in heterostructure Fe|Au|${\mathrm{Mn}}_3\mathrm{Ge}$. Also, we analyze the switching process of the ground state as a function of a spin current. We show a switching phase diagram, which contains switching and nonswitching regions. Our work suggests noncollinear antiferromagnets as an efficient platform for terahertz magnonics and ultrafast memory devices.

Altermagnets have attracted attention due to their compensating magnetic moments and nonrelativistic spin splitting. However, due to the limitation of the strict symmetry requirements, two-dimensional (2D) altermagnets are still rare, and the regulatory approaches are mostly volatile. Based on the low-energy effective $\mathit{k}·\mathit{p}$ model, a general approach to constructing bilayers with fully compensated ferrimagnetism (fFIM) whose properties are like altermagnets has been proposed, and the achieved layer-polarized anomalous Hall effect (LP-AHE) can be manipulated by the ferroelectric (FE) polarization in them. In the bilayers with fFIM, the coupling between FE polarization and interlayer A-type antiferromagnetism induces layer-locked Berry curvature, which provides advantages of antimagnetic interference and nonrelativistic spin splitting. Furthermore, during the symmetry operating of the bilayers with fFIM, the FE polarizations can be changed, and the reversals of the valley indices and the interlayer coupling energies can be achieved. The obtained tunable multiple couplings of spin, valley, and layer degrees of freedom induce LP-AHE in the bilayers with fFIM. Through first-principles calculations, we confirm this mechanism in the bilayer $\mathrm{C}{\mathrm{o}}_2\mathrm{NFCl}$ lattice by performing ${\widehat{M}}_z/\widehat{I}/{\widehat{C}}_{2z}$ symmetry operations. Manipulatable LP-AHE can be achieved in bilayers with fFIM, which reveals a method for achieving a tunable Hall effect in a broader range of 2D magnets.

In $A{M}_4{X}_8$ lacunar spinel systems, the formation of structural clusters in $T_d$ symmetry has led to the systems and its properties being commonly described by a $M_4$ molecular orbital picture and its associated spin, charge, and orbital degrees of freedom. However, the nature of the molecular orbital states in the cluster is yet to be elucidated by means of photoemission spectroscopy. Here, we show that the experimental photoemission spectra in ${\mathrm{GaNb}}_4{\mathrm{Se}}_8$ are consistent with the formation of a coherent, molecular orbital state resulting from the electronic tetramerization of ${\mathrm{Nb}}_4$, providing very direct validation of the molecular orbital picture in lacunar spinel systems. We find that, while the hybridization between Nb $4d$ and Se $4p$ in the valence band is non-negligible, the states crossing the Fermi level are mostly nonbonding, indicating that the ${\mathrm{Nb}}_4$ cluster picture is valid to describe the ground-state properties of ${\mathrm{GaNb}}_4{\mathrm{Se}}_8$. The spectral weight at the Fermi level is suppressed, indicating the presence of electronic correlations which can provide a coupling of the spin/orbital degrees of freedom with charge fluctuations.

We have developed an efficient method for performing density matrix renormalization group (DMRG) simulations of the SU($N$) Fermi-Hubbard chain, fully leveraging the SU($N$) symmetry of the problem. This method extends a previously developed approach for the SU($N$) Heisenberg model and relies on the systematic use of the semistandard Young tableaux (SSYT) basis in a DMRG algorithm “à la White.” Specifically, the method aligns the site-by-site growth process of the infinite-size part of the DMRG, in its original formulation, with the site-by-site construction of the SSYT (or Gelfand-like) basis, based on the chain of unitary subgroups $U\left(1\right)\subset U\left(2\right)\subset U\left(3\right)\subset U\left(4\right)\cdots$. We give special emphasis to the calculation of the symmetry-resolved reduced matrix elements of the hopping terms between the left and the right block, which makes direct use of the basis of SSYT and of the Gelfand-Tsetlin coefficients, offering a computational advantage in scaling with $N$ compared to alternative methods that rely on summing over Clebsch-Gordan coefficients. Focusing on the model with homogeneous hopping between nearest neighbors, we have calculated the ground-state energy as a function of $U$, i.e., the atom-atom interaction amplitude, up to $N=6$ for filling $1/N$ (one particle per site in average), and for one atom (respectively, hole) away from filling $1/N$. It allows us to compute the charge gaps and to estimate in the thermodynamical limit, the critical value $U_c$ (separating the Mott insulator from the metallic phase), which is proved to be finite (i.e., $U_c>0$) and to increase with $N$. Central charges $c$ are also extracted from the entanglement entropy using the Calabrese-Cardy formula and are consistent with the theoretical predictions: $c=N-1$, expected from the $\mathrm{SU}{\left(N\right)}_1$ Wess-Zumino-Witten conformal field theory in the spin sector for the Mott phase, and $c=N$ in the metallic phase, reflecting the presence of one additional (charge) gapless critical mode.

Interaction-induced charge orders with electronic origin occur as states of spontaneously broken symmetry in several materials platforms. An electronic mechanism for charge order requires an attractive component in the effective charge vertex. We put forward such a mechanism for the formation of unconventional charge density waves in a metal. These states result from the condensation of particle-hole pairs with finite wave vector and nonzero angular momentum and correspond to bond or loop current order on a lattice. The mechanism we describe can be viewed as Kohn Luttinger analysis in the particle-hole channel with finite transferred momentum. It incorporates one-loop spin and pairing corrections, which are then used as an input for a summation in the charge channel triggering an instability. We extend our analysis to a spin-fluctuation approach, where the effective charge interaction is dressed by the particle-hole ladder with exchanged momentum. We argue that this mechanism works for weakly interacting metals with a nested Fermi surface and a large number of fermion flavors. We apply the Kohn-Luttinger-like approach to square–PLXINSERT-, and triangular-lattice Hubbard models with $\mathrm{SU}(N_f$) flavour symmetry and show that it leads to different types of $p$-wave charge density waves. We also study effects beyond weak coupling at and away from Van Hove filling in terms of a phenomenological model with additional exchange interaction. In the vicinity of Van Hove filling, we obtain $d$-wave charge density waves with wave vectors determined by nesting as leading instabilities. In addition, we find another charge density wave with wave vector $K/4$ on the triangular lattice on both sides of the Van Hove filling. We demonstrate that this $K/4$ instability can win the competition against pairing for $N_f=4$ via an unbiased functional renormalization group calculation.

Weakly and strongly interacting quantum many-body systems, namely semiconductors and Mott insulators, are combined into a layered heterostructure. Via the hierarchy of correlations, we derive and match the propagating quasiparticle solutions in the different regions and calculate the transmission coefficients through these layered structures. As a proof of principle, we find the well-known transmission bands of a semiconductor heterostructure. Extending this idea to semiconductor and Mott insulator structures we calculate the transmittance and the resonance energies. Within a phase accumulation model we find analytical expressions for the scattering phase shift. Lastly, we find transmission curves with skewness for structures with applied voltage.

Layered parkerite-type ternary chalcogenide $\mathrm{B}{\mathrm{i}}_2\mathrm{R}{\mathrm{h}}_3\mathrm{S}{\mathrm{e}}_2$, featuring one-dimensional (1D) Rh-Rh chains, exhibits the coexistence of bulk superconductivity (SC) and charge-density-wave (CDW) order at ambient pressure. Here, we report an exceptional evolution of CDW and SC in pressurized $\mathrm{B}{\mathrm{i}}_2\mathrm{R}{\mathrm{h}}_3\mathrm{S}{\mathrm{e}}_2$. Upon compression, the CDW demonstrates a dome-shaped behavior that peaks at a critical pressure $P_{\mathrm{c}1}$ of ∼12 GPa, while the SC concurrently displays a valley-shaped evolution, indicating a competitive relationship between the two electronic orders. Theoretical calculations suggest that the unusual CDW evolution can be attributed to a nonmonotonic variation of the predominant Fermi surface nesting, along with an enhancement of the minority momentum-dependent electron-phonon coupling. Above $P_{\mathrm{c}2}\sim 33\mathrm{GPa}$, the valley-shaped SC plateaus at the superconducting transition temperature $T_{\mathrm{c}}\sim 2.33\mathrm{K}$, which can be attributed to a dimensional crossover from a quasi-2D to a 3D structure. Our findings demonstrate that the layered $\mathrm{B}{\mathrm{i}}_2\mathrm{R}{\mathrm{h}}_3\mathrm{S}{\mathrm{e}}_2$ provides an ideal platform for understanding a novel competing pathway between CDW and bulk SC, where the pressure-driven dome-shaped CDW is concurrent with an anticorrelated SC.

Entanglement of spin degrees of freedom can drastically alter the orbital exchange symmetry of electrons, switching their bunching and antibunching behaviors and the resultant current correlations in the Hanbury-Brown-Twiss interferometry. Here, we investigate the exchange correlation of quasiparticles with entanglement encoded in the Nambu spinors, or the electron-hole degree of freedom. In contrast to the conventional correspondence between spin entanglement and current correlation, we find that singlet (triplet) entanglement of Nambu spinors results in suppressed (enhanced) current correlation. This effect arises because the charge degree of freedom itself encodes the entanglement. We propose implementing this phenomenon in the edge states of a quantum Hall system, where the entangled states of the Nambu spinors can be continuously tuned by gate voltages. Our study reveals an unconventional relationship between entanglement and charge correlations, offering an effective approach for detecting entanglement of Nambu spinors.

Monolayer Janus transition metal dichalcogenides (TMDCs), such as WSeTe, exhibit Rashba-type spin-orbit coupling (SOC) due to broken out-of-plane mirror symmetry. Here, we theoretically demonstrate that pure spin Hall currents can be generated under light irradiation based on a tight-binding model. Rashba-type SOC plays a crucial role in determining the spin polarization direction and enhancing the generation efficiency of pure spin Hall currents. Our findings establish Janus TMDCs as promising materials for next-generation optospintronic devices.

We performed high-throughput density functional theory calculations of optical matrix elements between band edges across a diverse set of nonmagnetic two-dimensional monolayers with direct band gaps. Materials were ranked as potential optical emitters, leading to the identification of transition-metal nitrogen halides (ZrNCl, TiNBr, TiNCl) and bismuth chalcohalides (BiTeCl) with optical coupling strengths comparable to or exceeding that of ${\mathrm{MoS}}_2$. Despite strong in-plane dipole transitions, most two-dimensional materials underperform relative to bulk semiconductors due to a combination of factors, including the absence of out-of-plane optical components, reduced orbital degeneracy at the band edges due to lower crystal symmetry, and spin degeneracy lifting at non-time-reversal-invariant $k$ points. To elucidate the nature of interband transitions, we introduced the orbital overlap tensor and established a correlation between anomalous Born effective charges and optical coupling, linking charge redistribution to transition strength. We also identified chalcogen-mediated $d\text{−}d$ transitions as a key mechanism enabling strong optical responses in transition-metal dichalcogenides. An analytical model for the radiative recombination coefficient, incorporating multivalley effects, was derived and benchmarked against full first-principles calculations. Excitonic corrections were found to be essential for quantitative agreement with experiment. Notably, some direct-gap monolayers host dark excitons as their lowest-energy excitonic states, rendering them quasidirect band gap semiconductors and underscoring the importance of excitonic effects for tuning light emission properties in two-dimensional materials.

We employ the $\mathrm{SU}{\left(n\right)}_k$ Wess-Zumino-Witten (WZW) model in conformal field theory to construct lattice wave functions in both one and two dimensions. The spins on all lattice sites are chosen to transform under the $\mathrm{SU}\left(n\right)$ irreducible representation with a single row and $k$ boxes in the Young tableau. It is demonstrated that the wave functions can be reinterpreted as parton states, which enables efficient conversion to matrix product states, such that many physical properties can be evaluated directly. In one dimension, these wave functions describe critical spin chains whose universality classes are in one-to-one correspondence with the WZW models used in the construction. In two dimensions, our constructions yield model wave functions for chiral spin liquids, and we show how to find all topological sectors of them in a systematic way. Using the null vectors of Kac-Moody algebras, parent Hamiltonians of the $\mathrm{SU}{\left(3\right)}_k$ series are derived. The $\mathrm{SU}{\left(3\right)}_k$ chiral spin liquids are lattice analogs of non-Abelian spin-singlet fractional quantum Hall states, and the $k=2$ member hosts Fibonacci anyons.

We investigate the out-of-equilibrium lattice dynamics in the spin-ladder system ${\alpha }^{\prime }\text{−}{\mathrm{NaV}}_2{\mathrm{O}}_5$ using intense terahertz (THz) pump and near-infrared (NIR) probe spectroscopy. When quasi-single-cycle THz pulses interact with ${\alpha }^{\prime }\text{−}{\mathrm{NaV}}_2{\mathrm{O}}_5$ in its low-temperature, dimerized charge-ordered phase, they induce coherent oscillations in the time domain at the zone-folded Raman-active phonon frequency of 1.85 THz. By combining pump-probe measurements with lattice dynamics modeling based on the equation-of-motion approach, we propose that these oscillations arise from a nonlinear coupling between Raman-active and infrared (IR)-active phonon modes, with the latter being resonantly excited by the THz pulses. In contrast, excitation with NIR femtosecond laser pulses does not produce measurable vibrational dynamics, highlighting the unique potential of THz-driven, nonlinear light-matter interactions for the coherent and selective control of structural dynamics in quantum materials.

Bands with nontrivial topological indices have a topological obstruction preventing them from being represented by exponentially localized Wannier states. Here, we propose a procedure to construct exponentially localized Wannier functions that span a subspace of topologically obstructed bands through the use of the projection method. These Wannier functions form what we refer to as a “reduced Wannier representation,” indicating that the Wannier functions necessarily do not span the full topological manifold. By constructing supercells, we obtain reduced Wannier functions that break the primitive translational symmetry while capturing a substantial portion of the topologically obstructed manifold. This approach effectively decomposes the topological manifold into two subspaces: an itinerant subspace inheriting the topology and a localized trivial subspace represented by reduced Wannier functions. We consider the Haldane and Kane-Mele tight-binding models as the platforms for our investigation.