We study surface plasmons in minimally twisted gapped bilayer graphene that contains a triangular network of partial dislocations (or AB-BA domain walls) hosting topologically protected one-dimensional electronic states. We show that this system behaves as a plasmonic crystal and we calculate its band structure by solving classical equations of motion for charge dynamics on the network links with impedance boundary conditions at the network nodes. The plasmon dispersion exhibits several notable features such as multiple gapless branches, flat bands, and dissipationless modes at high-symmetry points. We compare our network-based formalism with the conventional random phase approximation and discuss when each approach is valid. Calculations of plasmon waves launched by local scatterers are presented to simulate terahertz nanoimaging experiments.

We report single-crystal neutron spectroscopy and bulk characterization of hydrothermally grown ${\mathrm{Nd}}_2{\mathrm{Sn}}_2{\mathrm{O}}_7$, revealing a dynamical moment fragmentation embedded within the all-in all-out ordered state. The spectra show a nearly flat band with pinch-point-like momentum dependence, accompanied by dispersive branches that generate half-moon features across multiple Brillouin zones. These defining signatures are captured quantitatively by a minimal dipolar-octupolar spin Hamiltonian, demonstrating excellent agreement between experiment and theory. The higher flat-mode energy helps account for the absence of dynamical interference in prior muon spin relaxation $\mu \mathrm{SR}$ studies, while the lack of any photonlike excitation imposes strict constraints on the proposed Coulombic antiferromagnet scenario. Our results extend dynamical moment fragmentation to ${\mathrm{Nd}}_2{\mathrm{Sn}}_2{\mathrm{O}}_7$ and identify it as a clean, tractable platform for quantitative exploration of emergent gauge-field physics and multipolar spin-wave dynamics in frustrated magnets.

We report the emergence of a transverse dielectric response in ${\mathrm{PbTiO}}_3/{\mathrm{SrTiO}}_3$ superlattices hosting polar vortex structures. Using second-principles simulations, we find that an electric field applied along one direction induces significant local polarization responses along orthogonal directions, with magnitudes approaching half that of the diagonal susceptibility components. These off-diagonal responses are strongly dependent on the topology of the vortex structure and can be deterministically tuned or even reversed via homogeneous electric fields or epitaxial strain. Notably, the transverse susceptibilities become comparable to the diagonal components during a field- or strain-induced transition to a polarization wave state. This discovery opens avenues for engineering reconfigurable nanoscale dielectric responses in topologically textured ferroelectric systems.

Kohn-Sham (KS) and post-KS density functional approximations (DFAs) often lack the chemical accuracy and may fail to capture qualitative trends for molecular interactions with ionic materials. This lack of reliability has hampered their use toward modeling surface chemistry and physics. Our studies on MgO(001) surface, show that the root cause for such discrepancies is density-driven errors rather than deficiencies in the exchange-correlation functional or errors from empirical dispersion corrections. For the post-KS random phase approximation (RPA) method, which incorporates dispersion interactions in a parameter-free manner, the density corrections based on the RPA singles (RPAS) method reduces the errors in RPA significantly, leading to remarkable agreement with high-level wavefunction methods while correctly predicting the order of small-molecule interactions with MgO(001) surface. Similar improvements are observed for the ${\mathrm{r}}^2\mathrm{SCAN}$-D4 functional, an empirically dispersion-corrected meta-GGA functional, by using the Hartree-Fock density. These consistent improvements across different classes of DFAs show that density-corrected methods can be used as a reliable and efficient approach to model molecule-surface interactions for ionic materials.

Deconfined criticality and gapless topological states have recently attracted growing attention as they lie beyond the traditional Landau paradigm. However, the deep connection between these critical states, particularly in lattice realizations, remains underexplored. In this Letter, we demonstrate that specific deconfined critical points can be regarded as intrinsically gapless topological states, using a one-dimensional lattice model. Combining field-theoretic arguments with large-scale numerical simulations, we establish the global phase diagram, revealing deconfined critical lines that separate two distinct spontaneous symmetry-breaking ordered phases. Crucially, we unambiguously demonstrate that the emergent anomaly inherent in deconfined criticality enforces robust topological edge modes near the boundary. This provides a general mechanism for realizing intrinsically gapless topological states by utilizing the inherent emergent anomaly at deconfined criticality. Our findings offer alternative perspective on deconfined criticality and advance the understanding of gapless topological phases of matter.

Infinite projected entangled-pair states (iPEPS) provide a powerful tool for studying strongly correlated systems directly in the thermodynamic limit. A core component of the algorithm is the approximate contraction of the iPEPS, where the computational bottleneck typically lies in the singular value or eigenvalue decompositions involved in the renormalization step. This is particularly true on GPUs, where tensor contractions are substantially faster than these decompositions. Here, we propose a contraction scheme for $C_{4v}$-symmetric tensor networks based on combining the corner transfer matrix renormalization group (CTMRG) with QR decompositions which are substantially faster, especially on GPUs. Our approach achieves up to two orders of magnitude speedup compared to standard CTMRG without loss of accuracy and yields state-of-the-art results for the Heisenberg and $J_1\text{−}{J}_2$ models in less than 1 h on an H100 GPU.

Here, we propose a method to introduce the magnon orbital Nernst effect in twisted collinear magnets through broken spatial inversion symmetry. We demonstrate that nonzero Berry curvature and orbital moments of magnons can be achieved by atomic translation, including spin-polarized transport of magnon orbital moments inherent to altermagnets. Based on first-principles calculations, we predict a potential bilayer structure of $\mathrm{VSeBr}$ exhibiting tunable transport properties. The magnetic ground state determined by the stacking orders, can be switched between altermagnetic and ferromagnetic phases, thereby enabling spin-polarized currents. Our work reveals perspectives for controlling spin-polarized magnon orbital currents based on layered magnetic structures.

Noncentrosymmetric superconductors (NCSs) with Rashba spin-orbit coupling (SOC) and in-plane magnetic fields have emerged as natural platforms for realizing both the bulk superconducting diode effect (SDE) and the Josephson diode effect (JDE)—phenomena characterized by unequal critical currents in opposite directions because of the simultaneous breaking of time-reversal and inversion symmetries. Using the quasiclassical Eilenberger formalism, we systematically investigate both the bulk SDE and the JDE in a clean NCS with Rashba SOC and in-plane magnetic fields. For the bulk system, we find that the diode efficiency can nominally approach its maximal value at the critical endpoint of the first-order Lifshitz transition between weak and strong helical phases featuring finite-momentum Cooper pairs, the latter marked by the emergence of Bogoliubov Fermi surfaces (BFSs). In a Josephson junction, we show that finite-momentum pairing in the superconducting leads is the dominant mechanism behind the JDE in short junctions, whereas in long junctions it is primarily governed by the Zeeman field in the normal region. In the long-junction regime, the diode efficiency additionally oscillates between positive and negative values as a function of the magnetic field at low fields, providing a route toward a highly tunable Josephson diode. At higher fields, the onset of BFSs in the strong helical phase leads to a sharp suppression of both the JDE and the Josephson current when the current direction is aligned with momenta along the BFS, resulting in strong anisotropy. We propose that this anisotropy in the Josephson current offers an alternative method for detecting BFSs, applicable to systems with or without a JDE.

Josephson scanning tunneling microscopy (JSTM) has emerged as an important technique for probing the superconducting order parameter at the atomic scale. However, the Josephson current in JSTM may behave quite differently when the coupling strength varies. Here, we push the junction to the deep point-contact regime, reaching a normal-state junction resistance of only $0.15·h/2e^2\approx 2k\mathrm{\Omega }$. We demonstrate, using kagome superconductors, that the zero-bias conductance, a key characteristic of the Josephson current, deviates strongly from the quadratic dependence on the normal-state conductance upon entering the deep point-contact regime. Furthermore, we observe a striking saturation of the zero-bias conductance, which we show arises from the series resistance in the circuit. This also serves as a cautious reminder when interpreting zero-bias conductance saturation or quantization in studies of exotic physics such as that of Majorana zero modes if the tip-sample junction resistance is extremely small. Finally, we identify an optimum regime where JSTM can be used as an atomic-scale probe for studying pair-density wave states in materials with low superconducting transition temperature, such as $\mathrm{A}{\mathrm{V}}_3\mathrm{S}{\mathrm{b}}_5$ kagome superconductors.

It has been shown that in magnets possessing an inversion center in the absence of deformations, a torsion-induced Dzyaloshinsky-Moriya interaction (tiDMI) can arise. A microscopic mechanism for this interaction is described, involving the transfer of angular momentum to the lattice upon electron reflection from the magnet's boundary. An estimate of the tiDMI constant is provided. It is demonstrated that tiDMI can lift the chiral degeneracy in helimagnets, and a way for experimentally observing this effect is proposed.

Chiral crystals exhibit enantiomer-dependent transport phenomena that generate pure spin or orbital currents, while the handedness sensitivity of spin and orbital Hall conductivities (SHC/OHC) remains insufficiently understood. Using first-principles calculations, we demonstrate that trigonal selenium and tellurium—prototypical chiral semiconductors—exhibit opposite signs of the SHC/OHC tensor elements ${\sigma }_{yx}^{S_y}$ and ${\sigma }_{yx}^{L_y}$ between their left- and right-handed enantiomers. This behavior originates from the mirror operation relating the two structures, described by space groups $P{3}_{2}21$ (left-handed) and $P{3}_{1}21$ (right-handed). Although both enantiomers share identical band structures and four nonzero SHC/OHC tensor components, ${\sigma }_{yx}^{S_y}$ and ${\sigma }_{yx}^{L_y}$ reverse sign due to the antisymmetric transformation of the spin/orbital Berry curvature under the $M_{xy}$ mirror operation. More generally, for mirror-related enantiomorphic structures, selected SHC/OHC tensor components can exhibit symmetry-governed sign reversal. For trigonal Se and Te, the calculated signs of these components can be directly correlated with the left- and right-handed structures under the chosen coordinate convention. These results clarify the symmetry origin of handedness-dependent SHC/OHC and suggest a possible route for correlating measurable SHC/OHC signals with structural handedness in specific chiral materials.

Altermagnets have zero net magnetization yet feature spin-split bands. Here, we investigate how slow lattice vibrations (phonons) influence both the intrinsic and externally induced spin polarizations in two-dimensional $d$-wave altermagnets. For the induced spin polarization, we employ a Rashba continuum model with electron-phonon coupling (EPC) treated at the static-Holstein level and analyze the spin Edelstein effect using the Kubo linear-response formalism to probe EPC-induced contributions. We find that under a specific symmetry-lowering pattern such as a piezomagnetically active strain that explicitly breaks the inherent $C_4\mathcal{T}$ symmetry, moderate-to-strong EPC progressively suppresses the induced polarization via both intraband and interband channels, with a threshold coupling marking the onset of complete spin Edelstein depolarization. The depolarization arises from a phonon-induced energy renormalization that leads to a complete collapse of the Fermi surface. While (de)polarization can occur even in the Rashba nonaltermagnetic phase, it remains isotropic. The presence of altermagnetism makes it anisotropic and breaks the conventional antisymmetry between spin susceptibilities that occurs with pure spin-orbit coupling, rendering the effect highly relevant for spintronic applications. We further investigate how the phonon coupling to the altermagnetic order, Rashba spin-orbit strength, and carrier doping collectively tune the depolarization. Our findings demonstrate that static phononic effects offer a powerful means for on-demand control of spin polarization, enabling reversible switching between spin-polarized and depolarized states—a key functionality for advancing spin logic architectures and optimizing next-generation spintronic devices.

Hydrogen-rich compounds that exhibit high-temperature superconductivity typically require extreme pressures, which severely limits their practical applicability. Recent theoretical predictions of the complex hydride ${\mathrm{Mg}}_2{\mathrm{IrH}}_6$ have introduced a new family of ${\mathit{M}}_2{\mathit{X}\mathrm{H}}_6$-type hydrides, highlighting the potential for high-temperature superconductivity at near-ambient pressure. Motivated by this, we have performed high-throughput first-principles investigations of the ${\mathit{M}}_2{\mathit{X}\mathrm{H}}_6$ family (M = IA, IIA, IIIA, IIB metals; X = B, C, N) to identify dynamically stable hydrides and explore their superconducting properties. Eleven boron-based hydrides, ${\mathit{M}}_2{\mathrm{BH}}_6$ (M = Li, Na, K, Rb, Cs, Ca, Sr, Ba, Sc, Y, La), featuring ${\mathrm{BH}}_6$ octahedral units have been identified. Notably, ${\mathrm{Li}}_2{\mathrm{BH}}_6$ is dynamically stable down to 16 GPa and exhibits a superconducting critical temperature of 121.25 K. Electronic structure and phonon analyses indicate that high-frequency hydrogen vibrations from strong B–H covalent bonding, reinforced by light Li atoms, dominate the electron–phonon coupling. In contrast, noble-metal-based ${\mathrm{Li}}_2{\mathit{X}\mathrm{H}}_6$ compounds (X = Cu, Ag, Au) exhibit distinct superconducting mechanisms, driven by $d$ electrons at the Fermi level and low-frequency metal vibrations. These findings expand the compositional space of the ${\mathit{M}}_2{\mathit{X}\mathrm{H}}_6$ family and highlight ${\mathrm{Li}}_2{\mathrm{BH}}_6$ as a promising candidate for near-ambient-pressure high-$T_c$ superconductivity.

The recent discovery of high-temperature superconductivity in the bilayer nickelate ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ has spurred intense interest in exploring analogous mechanisms in other transition metal oxides. This raises a pivotal question: can cuprates, as neighbors to nickelates in the periodic table, host similar two-orbital superconductivity? Here, we systematically investigate the electronic structure of a series of designed Ruddlesden-Popper cuprates. Our calculations reveal that the parent compound ${\mathrm{La}}_3{\mathrm{Cu}}_2{\mathrm{O}}_7$ is a weakly correlated metal, and hole doping fails to induce strong correlation. We find that the actual valence of the copper cations becomes strikingly pinned around $+2.3$, far away from the targeted $d^8$ configuration. This valence pinning is attributed to the in- herent charge-transfer nature of cuprates. We propose this mechanism as a general principle explaining the robust single-orbital physics consistently observed in the cuprate family, holding true even in materials like the high-$T_c$ superconductor ${\mathrm{Ba}}_2{\mathrm{CuO}}_{3+\delta }$ that appear structurally primed for two-orbital activity. Our results therefore conclude that the route towards two-orbital superconductivity is fundamentally obstructed in cuprates, providing a crucial constraint for the future design of high-temperature superconductors.

Symmetry analysis is a cornerstone of modern physics, with charge- and spacetime-orientation-reversal (CRT) symmetry being a subject of particular interest. Recent research has revealed that the CRT symmetry for fermions exhibits a fractionalization distinct from the ${\mathbb{Z}}_2^{\mathcal{C}}\times {\mathbb{Z}}_2^{\mathcal{R}}\times {\mathbb{Z}}_2^{\mathcal{T}}$ symmetry for scalar bosons. In fact, the CRT symmetry for fermions can be extended by internal symmetries such as fermion parity ${\mathbb{Z}}_2^F$, chiral symmetry ${\mathbb{Z}}_2^{\chi }$, and continuous symmetries, thereby forming a group extension of the aforementioned ${\mathbb{Z}}_2$ direct product, and suffices to rule out bilinear mass terms. In the conventional framework, a Majorana fermion is defined by a single Dirac fermion with trivial charge conjugation. However, this definition encounters a fundamental challenge when the spacetime dimension $d+1=5,6,7mod8$, where the real dimension of Majorana fermion (${\dim }_{\mathbb{R}}{\chi }_{\mathcal{C}\ell (d,0)}$) aligns with the real dimension of Dirac fermion (${\dim }_{\mathbb{R}}{\psi }_{\mathcal{C}\ell \left(d\right)}$), rather than being half as in other dimensions. This peculiarity necessitates the introduction of a symplectic Majorana fermion, defined by a pair of Dirac fermions with trivial charge conjugation, to account for the discrepancy. To include these two types of Majorana fermions, we embed the Majorana theory in $n_{\mathbb{R}}$ and define the Majorana fermion field as a representation of the real Clifford algebra, which exhibits an eightfold Bott periodicity. Within the Hamiltonian formalism, we identify the eightfold CRT-internal symmetry groups across general spatial dimensions. In the case of Dirac fermions, the fermion field is defined as a representation of the complex Clifford algebra, which has a twofold Bott periodicity. Interestingly, we discover that the CRT-internal symmetry groups exhibit an eightfold periodicity that is distinct from that of the complex Clifford algebra. In certain dimensions where distinct mass terms can span a mass manifold, the CRT-internal symmetries can act nontrivially upon this mass manifold. Employing domain wall reduction method, we are able to elucidate the relationships between symmetries across different dimensions.

We present an analysis of a square-lattice Harper-Hofstadter model with a periodically varying magnetic flux with time. By switching the dimensionless flux per plaquette between a set of values $\{p_j/q_j\}$ the Floquet quasienergy spectrum is folded into $Q=\mathrm{lcm}\left\{q_j\right\}$ bands. We determine closed-form analytical solutions for the quasienergy spectrum and Chern numbers for the $-1/2\to 1/2$ flux-switching case, as well as the Rudner-Lindner-Berg-Levin (RLBL) winding invariants $W$ numerically, and construct the corresponding topological phase diagram for arbitrary driving period. We find that generic flux-switching drives feature interlaced Hofstadter butterfly quasienergy spectra which may host Floquet topological phases with no static counterpart, and the gaps in the spectrum may be labeled according to a Diophantine equation which relates the quasienergy gap index to the fluxes attained in the drive and their associated per-step windings.

Type-II multiferroics offer a promising route to strong magnetoelectric coupling due to the magnetic-order-driven ferroelectricity. Most experimentally realized type-II multiferroics exhibit noncollinear magnetic order, whose complex interaction with external fields can impede the practical control of magnetoelectric effects. In contrast, type-II multiferroics with collinear magnetic order remain underexplored, with prior work largely limited to conventional antiferromagnets. In this work, using Landau theory and symmetry analysis, we investigate spin-order-induced ferroelectricity in collinear ferrimagnetic systems and derive the criteria in the minimal-case scenario. According to these criteria, we perform a rapid and efficient search and ultimately identify three promising ferrimagnetic multiferroic candidates from the Inorganic Crystal Structure Database (ICSD). Among them, the largest net magnetic moment per unit cell (u.c.) reaches 3.0 ${\mu }_B$, and the maximum polarization reaches 0.08 $\mu \mathrm{C}/{\mathrm{cm}}^2$, comparable to the typical multiferroics material ${\mathrm{TbMnO}}_3$. In addition, for the altermagnetic system, we searched for known magnetic structures in the MAGNDATA database and identified ${\mathrm{MnSe}}_2$ as a promising candidate material, exhibiting a polarization as high as 0.07 $\mu \mathrm{C}/{\mathrm{cm}}^2$. Notably, our results show that ferroelectric polarization behavior provides a clear criterion for distinguishing the two experimentally reported magnetic structures of ${\mathrm{MnSe}}_2$.