Previous research [Nat. Phys. 15, 1065 (2019)] has confirmed that helium can react with ice to form a superionic compound under extreme condition relevant to the “hot ice” layers of ice giants. While these findings reshape our understanding of these planetary materials, the thermal transport properties of such compounds, which are crucial parameter for modeling the dynamics and thermal history of these planets, remain uncharacterized. Here, we use first-principles calculations and the linearized phonon Boltzmann transport equation to systematically investigate the phonon dispersion, thermal conductivities, group velocities, phonon lifetimes, Grüneisen parameters, and mean free paths of ${\mathrm{He}}_2{\mathrm{H}}_2\mathrm{O}$ in both $I{4}_{1}md$ and $Fd\overline{3}m$ phases under high pressure conditions. Our results demonstrate marked differences in the transport dynamics of helium between ice VII and ice X sublattice attributed to the distinct strength and rigidity of hydrogen bonds. The room-temperature thermal conductivities of $I{4}_{1}md$ phase reach 16.4 W ${\text{m}}^{-1}$ ${\text{K}}^{–1}$ at 30 GPa and 27.9 W ${\text{m}}^{–1}$ ${\text{K}}^{–1}$ at 55 GPa, which are comparable to the experimental measurement of ice VII (∼25 W ${\text{m}}^{–\hspace{0.17em}}{\text{K}}^{–1}$ at 22 GPa), suggesting that the incorporation of interstitial He moderately suppresses the transport efficiency of phonon. However, the $Fd\overline{3}m$ phase exhibits dramatically reduced thermal conductivities of 1.4 W ${\text{m}}^{–\hspace{0.17em}}{\text{K}}^{–1}$ at 60 GPa and 4.3 W ${\text{m}}^{–\hspace{0.17em}}{\text{K}}^{–1}$ at 80 GPa, where optical phonons dominate the thermal transport with contributions exceeding 50%. These exceptional values mainly arise from synergistic effects of larger phonon group velocity, stronger anharmonicity, shorter phonon lifetime, and smaller mean free path. Such suppression of thermal conductivity in $Fd\overline{3}m\text{−}{\mathrm{He}}_2{\mathrm{H}}_2\mathrm{O}$ compound may alter conductivity distributions in the convective layer, inhibit helium-hydrogen demixing, and reduce heat transport efficiency, which may explain the multipolar magnetic field and anomalously low thermal flux observed in Uranus and Neptune. Our works elucidate the physical mechanism underlying the low thermal conductivity in the He-${\mathrm{H}}_2\mathrm{O}$ system under extreme conditions and provide critical insights into the dynamic process and thermal evolution of ice giants.

We consider quenches of a quantum system that is prepared in a canonical equilibrium state of one Hamiltonian and then evolves unitarily in time under a different Hamiltonian. Technically, our main result is a systematic expansion of the pre- and postquench canonical ensembles in the quench strength. We first demonstrate how this can be used to predict the system's temperature after the quench from equilibrium properties at the prequench temperature. For a thermalizing postquench system, it furthermore allows us to calculate equilibrium observable expectation values. Finally, in the presence of additional conserved quantities besides the Hamiltonian, we obtain a hierarchy of necessary conditions for thermalization towards the (postquench) canonical ensemble. At first order, these thermalization conditions have a nice geometric interpretation in operator space with the canonical covariance as a semi-inner product: The quench operator (difference between post- and prequench Hamiltonians) and the conserved quantity must be orthogonal in the orthogonal complement of the postquench Hamiltonian. We illustrate the results numerically for a variety of setups involving integrable and nonintegrable models.

The growing interest in exciton-polaritons has driven the need to manipulate their motion and engineer their band structures to the forefront of contemporary research. In this study, we explore the band structures that emerge from a spatially modulated potential, realized through the use of an optical conveyor belt. By leveraging Bloch theory and conducting a meticulous analysis of the time evolution of polariton intensity in Fourier space, we have derived the energy dispersion relations both analytically and numerically within the context of a static lattice model. For time-dependent potentials, we employ the Lagrange variational method to elucidate the dynamics of polariton motion. Our results reveal that polaritons exhibit linear dispersion and follow linear trajectories with minor oscillations superimposed. In this investigation, we not only deepen our fundamental understanding of exciton-polaritons but also provide a robust tool for advancing photonic devices and exerting precise control over current transport in quantum computing. Our findings pave the way for future innovations in high-speed and high-performance technologies.

Altermagnetism has been proposed as a distinct class of antiferromagnets exhibiting momentum-dependent spin splitting band structures without requiring spin-orbit coupling. Recently, ${\mathrm{KV}}_2{\mathrm{Se}}_2\mathrm{O}$ has been identified as a metallic room-temperature altermagnet with $d$-wave spin-momentum locking. Here, we investigate the magnetic structure of ${\mathrm{KV}}_2{\mathrm{Se}}_2\mathrm{O}$ in both polycrystalline and single-crystal samples using neutron diffraction techniques. The system exhibits G-type antiferromagnetic structure with a Néel temperature $T_N\approx$ 400 K. Notably, substantial broadening of magnetic peaks was observed along $L$ at low temperatures in single crystals, consistent with the coexistence of G-type AFM order and a $c$-axis spin density wave. These results demonstrate that bulk ${\mathrm{KV}}_2{\mathrm{Se}}_2\mathrm{O}$ cannot host altermagnetism.

It is well known that the intrinsic anomalous Hall effect (AHE) arises from the integration of the nonzero Berry curvature (BC), conventionally observed in Dirac/Weyl and nodal line semimetals. Moreover, nodal surface semimetals are expected to exhibit more significant BC under the prevalence of degenerate points near the Fermi level. In this work, we report the detection of a giant AHE in the kagome magnet ${\mathrm{Fe}}_3\mathrm{Ge}$ with a two-dimensional nodal surface at the $k_z=\pi$ plane, exhibiting an anomalous Hall conductivity (AHC) of 1500 ${\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$ at 160 K, which exceeds that of many typical kagome topological materials. This finding suggests another platform for searching large AHC materials and facilitates potential room-temperature applications in spintronic devices and quantum computing.

Linear-in-temperature resistivity ($T$-linear) and linear-in-field ($H$-linear) magnetoresistance (MR) are two typical characteristics of the strange-metal state in high-temperature (high-$T_{\text{c}}$) superconductors. Unraveling the relationship between the two phenomena may provide critical insights into the underlying mechanisms of strange metallicity and superconductivity. In this study, we investigate the high-field MR of the trilayer cuprate ${\text{Tl}}_{\text{2}}{\text{Ba}}_{\text{2}}{\text{Ca}}_{\text{2}}{\text{Cu}}_{\text{3}}{\text{O}}_{\text{10}+\delta }$ and perform a comparative analysis with other high-$T_{\text{c}}$ superconductors, including single-layer cuprates and iron-based systems. In all systems, MR exhibits an $H^{\text{2}}$ dependence at high temperatures, which gradually evolves to an $H$-linear dependence as temperature decreases. Remarkably, we found that the ratios of $H$-linear to $T$-linear coefficients are on the same order of magnitude (with the mean value of $0.40\pm 0.22$) across a broad range of materials, despite significant differences in lattice structure, Fermi surface geometry, and superconducting transition temperature. A further combination with MR simulations suggests momentum-dependent anisotropic scattering may be the origin for $H$-linear MR in various high-$T_{\text{c}}$ superconductors, which may also be the origin of $T$-linear resistivity.

We provide a method to compute Slavnov overlaps in the Lieb-Liniger model using the steepest descent method of the Riemann-Hilbert problem. To do so, we employ the Matsuo-Kostov representation of the Slavnov overlaps to derive an integral equation for the respective resolvent, and then represent this equation as a Riemann-Hilbert problem. We demonstrate the validity and applicability of the method by computing the Anderson orthogonality catastrophe in the $c\to \infty$ limit, corresponding to free fermions.

The recently proposed Clifford augmented density matrix renormalization group (CA-DMRG) method seamlessly integrates Clifford circuits with matrix product states and takes advantage of the expression power from both. CA-DMRG has been shown to be able to achieve higher accuracy than standard DMRG on commonly used lattice models, with only moderate computational overhead compared to the latter. In this work, we propose an efficient scheme in CA-DMRG to deal with ab initio quantum chemistry Hamiltonians and apply it to study several molecular systems. Our numerical results show that CA-DMRG can reach higher accuracy than DMRG using the same bond dimension, pointing out a promising route to push the boundary of solving ab initio quantum chemistry with strong static correlations.

The realization of intrinsic second-order topological insulators (SOTIs) in two-dimensional magnetic systems has attracted considerable attention due to their unique physical properties and potential applications. The implementation of such materials fundamentally relies on nontrivial topological and magnetic orders. Although general design frameworks have been established through band engineering strategies, such as Zeeman field manipulation, the exploration of intrinsic magnetic SOTI systems still faces challenges. Followed by first-principles calculations, in this work, we report a series of intrinsic magnetic SOTIs ${\mathrm{Cr}}_{2}XY (X/Y=\mathrm{P},\mathrm{As},\mathrm{Sb})$ monolayers, which exhibit out-of-plane or in-plane intrinsic magnetic order and high Curie temperatures ($>800\mathrm{K}$). Taking ${\mathrm{Cr}}_2{\mathrm{P}}_2$ and ${\mathrm{Cr}}_2{\mathrm{As}}_2$ monolayers as representative examples, we systematically reveal their second-order topological characteristics base on the Wannier functions of $p\text{−}d$ orbitals. We demonstrate floating edge states with second-order topology within the bulk gap and further elucidate topological characteristics using the nested Wilson loop method. Remarkably, corner-state substitution processes driven by discrete length modulation were observed in finite-sized nanoribbons. This provides a perspective for understanding the size effects of second-order topological corner states.

This study addresses the knowledge gap regarding how nanoscale surface roughness and chemical functionalization impact the Derjaguin-Landau-Verwey-Overbeek (DLVO) forces. To this end, force measurements in a spherical-plate geometry were carried out using an atomic force microscope (AFM) on 1-hexadecanethiol self-assembled monolayers (SAMs) on nano-roughened gold (Au) surfaces prepared by the template-stripping method. The measurements were performed in unsalted (DI water) and salted solutions ($\left[\mathrm{NaCl}\right]=0.1$ mM) between surfaces of varying roughness. The experimental force curves were compared with the predictions of DLVO theory using a maximum likelihood method to extract the essential parameters describing the electrical double layer (i.e., the Debye length ${\lambda }_D$ and the surface potentials ${\psi }_1,{\psi }_2$) under different extrapolation assumptions for the van der Waals–Casimir contribution, namely the Drude and Plasma models. For nonfunctionalized Au surfaces both in DI water and in the salted solution, the repulsive electrostatic double-layer force increased with increasing roughness. Moreover, the SAM in DI water modified the surface characteristics reduced the Debye length, where the effect was more pronounced on the rougher surface. In contrast, the SAM in the salted solution displayed a more complicated trend. Finally, no statistically significant differences were observed between the predictions using the two extrapolation models for the van der Waals–Casimir force. However, the Drude model systematically yielded higher likelihood values suggesting that it may better represent the experimental data for liquid media.

The electronic transport in few-layer black phosphorus (FLBP) nanoribbons is studied theoretically. The system is modeled on the basis of band structures, which have been measured recently by $\mu$-ARPES experiments. We show that the anisotropic bands of FLBP lead to highly anisotropic transport properties; while the current in one direction can be rather focused, it can be strongly dispersed in the orthogonal direction. The low-energy current is concentrated in the central layers due to the vertical confinement of the electrons. In FLBP pn junctions, generated by the electrostatic potential of a gate contact, the electrons pass through the interface of the junction, if it is oriented along the zigzag direction of FLBP. If the junction is rotated by 90 degrees and oriented along the armchair direction, the current is reflected completely for all angles of incidence and for a wide range of electron energies. This omnidirectional total reflection is named anti-super-Klein tunneling because of opposite pseudospins of the electrons in the two regions of the pn junction. The effect is quite independent from the number of layers and should be observed even in the bulk. The effect of oxidation of the top layer of FLBP pn junctions is investigated and it is found that, while the current flow in the top layers is strongly suppressed, the anti-super-Klein tunneling persists.

Altermagnets offer a promising platform for dissipationless spin transport by combining zero net magnetization with spontaneous nonrelativistic spin-split bands. Transport of angular momentum by magnons modes is another interesting aspect in altermagnets. Here, we develop a quantum-kinetic theory for thermally driven magnon currents that cleanly separates Berry-curvature-driven intrinsic contributions from Drude-like scattering-dependent terms. Applying this framework to a collinear honeycomb antiferromagnet with anisotropic altermagnetic exchange interaction and Dzyaloshinskii-Moriya interaction between next-nearest neighbor, we reveal spin-split magnon bands that support both intrinsic and extrinsic magnonic spin Nernst and Seebeck currents. For realistic parameters, we predict a sizable magnon spin-splitting angle (about 3.3 degrees) and a pure transverse spin current capable of exerting a strong spin-splitter torque suitable for magnetization switching.

To date, 1788 obstructed atomic insulators (OAIs) characterized by charge centers not localized at atomic positions have been identified. However, only a small fraction qualify as insulating inorganic electrides (IEs), making this subclass—OAI IEs—a largely unexplored territory in materials science. Herein, through an unconventional screening approach, we uncover 33 such OAI IEs from the full OAI dataset, including six electrically neutral and seven negatively charged candidates, fundamentally challenging the longstanding view that IEs are intrinsically electron rich in nature. Moreover, the synergistic effect between the electronegativity difference of cations and anions, bond lengths, and the size of interstitial positions determines the presence of interstitial anion electrons in OAI IEs. Unlike previously reported metallic IEs, the insulating nature of the OAI IEs enables the emergence of multidimensional boundary phenomena, including coexisting surface and hinge states. We identify 22 candidates that host a low work function $[\mathrm{\Phi }\left(\mathrm{WF}\right)<4 \mathrm{eV}]$, a feature that markedly boosts the efficiency of ammonia synthesis. These results involve the screening, investigation, and application of insulating IEs, effectively linking the potential of insulating IEs to fields such as topological quantum chemistry, boundary engineering, and energy research.

We investigate the magnetotransport properties of a diluted half-filled one-band Hubbard model with second-nearest-neighbor hopping on a simple cubic lattice, aiming at exploring the possibility of metallicity in diluted antiferromagnetic (AF) systems. Our semiclassical Monte Carlo calculations reveal an AF metallic regime in diluted correlated materials. This unexpected metallic regime naturally leads to a central question: How does the introduction of dilution into an AF material, especially with long-range magnetic interactions, induce metallicity—a feature not commonly associated with AFs? To address this question, we demonstrate that, when the on-site repulsive Hubbard interaction strength is set to zero on a percentage of the sites (site dilution), the insulating state weakens due to percolative conduction among the diluted sites at low temperatures. Remarkably, this occurs without any significant alteration to the underlying long-range AF ordering in the system, thereby providing a pathway to realize AF metals. In addition, we show how the sublattice-dependent hopping can be exploited to engineer spin-polarized half-metallic AFs. Overall, our numerical results collectively provide a basis for understanding the combined effect of site dilution and competing interactions, which will assist in the design of AF metals for future spintronic applications.

We investigate the impact of crystal alignment on excitonic behavior in ${\mathrm{WSe}}_2/{\mathrm{MoS}}_2$ van der Waals heterostructures by comparing eclipsed (AA) and staggered (AB) stacking configurations. Our first-principles and symmetry-based analysis reveal that interlayer stacking symmetry plays a central role in determining the nature of electron-hole pairs. We uncover a rich variety of excitonic states, including spatially confined two-dimensional (2D) excitons, delocalized three-dimensional (3D) excitons, and charge-transfer (CT) excitons with interlayer character. The dimensionality and optical activity of these excitons are governed by the interplay among orbital character, interlayer hybridization, and symmetry-imposed selection rules. Our findings establish general principles for engineering excitonic properties in van der Waals heterostructures through controlled layer orientation and stacking order.

Atomically thin layers of metals deposited on semiconductors display a variety of physical properties such as superconductivity, charge density waves, topological phases, strong spin-orbit (Rashba) splitting, among others. To access these exotic phases and induce new ones, it is necessary to control and tune the energies of the electronic states of those heterostructures. In this work we investigate the engineering of the band structure of the two-dimensional Bi/Si(111) $\beta$ phase using a modulation doping approach based on boron segregation at the surface. We demonstrate that the Bi-induced Rashba bands can be displaced in energy by up to 200 meV without altering their strong Rashba parameter. Importantly, while the Bi states shift upward, the underlying Si valence states remain essentially fixed, which rules out a simple band-bending scenario. Our density functional theory calculations reveal that the displacement originates from changes in the hybridization of Si states near the surface, induced by the presence of B atoms. This selective mechanism halves the distance of the Rashba-split states from the Fermi level, opening the way to their exploitation in transport and spintronic devices and highlighting the broader potential of modulation doping as a band-engineering strategy for two-dimensional metals on semiconductors.

Multisubband plasmon (MSP) modes in heavily doped InAs/GaSb broken-gap quantum wells grown via molecular beam epitaxy (MBE) are investigated. An eight-band $\vec{k}·\vec{p}$ semiclassical model accurately predicts ellipsometric spectra, reflecting strong subband hybridization and nonparabolicity. In contrast, single-band plasmon models show qualitative discrepancies with experiment, even with adjusted effective masses. These findings highlight the potential of broken-gap wells for quantum technologies leveraging interband coupling and wavefunction hybridization.

Ultrafast spin injection across magnetic/nonmagnetic (FM/NM) interfaces represents a pivotal mechanism for spintronic applications, yet the governing principles of interlayer-mediated spin dynamics remain elusive. Herein, we systematically investigate femtosecond-scale spin transfer in $\mathrm{Cr}{X}_3/\mathrm{W}{Z}_2 \left(X=\mathrm{Br},\mathrm{I};Z=\mathrm{S},\mathrm{Se}\right)$ van der Waals heterostructures through combined first-principles calculations and nonadiabatic molecular dynamics simulations. Our results demonstrate that asymmetric interlayer charge transfer, accompanied by spin-flip processes, mediates ultrafast (9–27-fs) spin injection from FM $\mathrm{Cr}{X}_3$ to NM $\mathrm{W}{Z}_2$ layers. Crucially, the magnetic moment persistence in NM layers exhibits material-dependent lifetimes $\left(\mathrm{CrB}{\mathrm{r}}_3/\mathrm{WS}{\mathrm{e}}_2>\mathrm{CrB}{\mathrm{r}}_3/\mathrm{W}{\mathrm{S}}_2>\mathrm{Cr}{\mathrm{I}}_3\mathrm{WS}{\mathrm{e}}_2>\mathrm{Cr}{\mathrm{I}}_3/\mathrm{W}{\mathrm{S}}_2\right)$ on picosecond timescales. This behavior is governed by three key factors: (i) bandgap-dependent nonadiabatic coupling, where ${\mathrm{CrBr}}_3$ systems exhibit prolonged retention due to their larger energy gaps; (ii) spin-orbit coupling and electron-phonon coupling synergistically modulate spin-flip and transfer dynamics; and (iii) built-in electric fields that selectively accelerate or decelerate the interlayer charge transfer. These insights offer a comprehensive framework for understanding interfacial spin dynamics and provide design principles for tailoring spin lifetimes in two-dimensional heterostructure-based spintronic devices.

Generally, materials near instabilities have low thermal conductivity. However, we predict that semiconducting layered ${\mathrm{NiO}}_2$, which is experimentally marginally stable and is based on chemically unstable tetravalent Ni, has an extremely high 300 K thermal conductivity within its layers, approximately 4 times that of sapphire and even approaching the thermal conductivity of beryllia, the highest thermal conductivity oxide. The explanation for this result is in terms of the unusual bonding of the ${\mathrm{NiO}}_2$ layers and the resulting phonon dispersions and anharmonicities. Specifically, the longitudinal acoustic and one of the transverse acoustic branches are bunched, related to unusual bonding for a transition metal oxide, while the other transverse acoustic branch is very soft. This leads to a low scattering phase space and high in-plane thermal conductivity.