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Topologically protected corner states serve as a key indicator for two-dimensional higher-order topological insulators, yet they have not been experimentally identified in realistic materials. Here, by utilizing the effective tight-binding model and symmetry arguments, we establish a connection between higher-order topological insulators and twisted bilayer kagome lattices. We find that the topologically nontrivial bulk band gap arises in the twisted bilayer kagome lattice system due to twist-induced intervalley scattering, leading to the emergence of higher-order topological insulators with a range of commensurate twist angles, and the higher-order band topology is verified by the second Stiefel-Whitney number and fractionally quantized corner charges. Moreover, we investigate the influence of disorder and charge density wave order on the stability of higher-order topological insulator phases. The results show that the corner states of twisted bilayer kagome lattice systems are robust with respect to disorder and charge density wave. Our work not only provides a feasible approach to realize the readily controllable higher-order topological insulator phases by employing a simple twist technique, but also demonstrates that the twisted bilayer kagome lattice systems exhibit the robustness of higher-order band topology, making it feasible to check above prediction in experiments., Comment: 7 pages, 4 figures

Discrete groups are widely used in the expression of flavor symmetries of leptons. In this paper, we employ a novel mathematical object called group-algebra (GA) to describe symmetries of the leptonic mass matrices. A GA element is constructed by a discrete group with continuous parameters. For a GA element, there is an equivalent symmetry which can be continuous, discrete, and hybrid. According to the equivalence between a GA element and other symmetries, we perform a classification of 198 nontrivial elements of the GA generated by the group $S_{4}$. Based on the results of the classification, the phenomenological consequences of the $S_{4}$ GA are illustrated., Comment: 11 pages

Extending geodetic and astrometric Very Long Baseline Interferometry (VLBI) observations from traditional centimeter wavebands to millimeter wavebands offers numerous scientific potentials and benefits. However, it was considered quite challenging due to various factors, including the increased effects of atmospheric opacity and turbulence at millimeter wavelengths. Here, we present the results of the first geodetic-mode VLBI experiment, simultaneously observing 82 sources at 22/43/88/132 GHz (K/Q/W/D bands) using the Korean VLBI Network (KVN). We introduced the frequency phase transfer (FPT) method to geodetic VLBI analysis, an approach for calibrating atmospheric phase fluctuations at higher frequencies by transferring phase solutions from lower frequencies. With a 2-minute scan, FPT improved the signal-to-noise ratio (SNR) of most fringes, some by over 100%, thereby enhancing the detection rate of weak sources at millimeter wavebands. Additionally, FPT reduced systematic errors in group delay and delay rate, with the weighted root-mean-squares (WRMS) of the post-fitting residuals decreasing from 25.0 ps to 20.5 ps at the W band and from 39.3 ps to 27.6 ps at the D band. There were no notable differences observed in calibrating atmospheric phase fluctuations at the K band (WRMS = 12.4 ps) and Q band (WRMS = 11.8 ps) with the KVN baselines. This experiment demonstrated that the millimeter waveband can be used for geodetic and astrometric applications with high precision., Comment: 17 pages, 6 figures, accepted by The Astronomical Journal. Your feedback to improve the manuscript would be greatly appreciated

With significant advances in classifying and cataloguing topological matter, the focus of topological physics has shifted towards quantum control, particularly the creation and manipulation of topological phases of matter. Floquet engineering, the concept of tailoring a system by periodic fields, offers a powerful tool to manipulate electronic properties of condensed systems, and even to create exotic non-equilibrium topological states that are impossibly present in equilibrium scenarios. In this perspective, we give a brief review of recent progress in theoretical investigations of Floquet engineering topological states from effective models towards realistic materials. We show that light irradiation can realize various desired topological states through the introduction of symmetry breaking, such as first- and higher-order Weyl fermions, quadrupole topological insulator with periodic driving and disorder, quantum anomalous Hall effects with a tunable Chern number, as well as beyond. Moreover, based on first-principles calculations and Floquet theorem, we show several realistic material candidates proposed as potential hosts for promising Floquet topological states, facilitating their verification in experiments. We believe that our perspective on Floquet engineering of topological states will advance further studies of rich exotic light-induced phenomena in condensed matter physics., Comment: 40 pages, 11 figures

The interplay between magnetism and strong topological insulator gives rise to distinct new topological phases and various intriguing phenomena, attracting significant attention in recent years. However, magnetic effects in weak topological insulators remain largely unexplored. In this work, we systematically investigate the magnetic effect on thin films of weak topological insulators. We focus on ferromagnetic and antiferromagnetic effects, which have been extensively studied in strong topological insulators, as well as the recently highlighted altermagnetic effect. We reveal that the interplay between magnetism and weak topological insulators leads to a variety of Hall effects in the absence of an external magnetic field, including the metallic quantum anomalous Hall effect without chiral edge states, the quantum anomalous Hall effect with a higher Hall conductance plateau, the quantized layer Hall effect, the metallic half-quantized valley-like Hall effect, and a quantized valley-like Hall effect. This work provides valuable insights for exploring magnetic effect on weak topological insulators.

Floquet engineering with periodic driving as a powerful tool for designing desirable topological states has been the subject of intense recent studies. Here, we present the application of Floquet engineering to investigate evolution of topological triple fermions under irradiation of circularly polarized light (CPL), a phenomenon that currently remains a mystery. By using first-principles calculations and Floquet theorem, we demonstrate that WC-type TiO and its analogues are promising candidates for Floquet engineering of triple fermions. The symmetry analysis reveals that the electric field of CPL can break the specific symmetries, such as the time-reversal symmetry and its combination of spatial symmetries, inducing a transition to a flexibly controllable Weyl semimetallic phase. The survived spatial symmetry, controlled by light, guarantees that the Weyl nodes are located along the high-symmetry line or in high-symmetry planes in momentum space. Our findings focusing on Floquet engineering in realistic materials featured by triple fermions would facilitate both theoretical and experimental interest., Comment: 6 pages, 4 figures

Linear-in-$k$ Rashba spin-orbit coupling is crucial for achieving topological superconductivity. The wave vector dependence of this spin-orbit coupling can vary across materials, exhibiting linear, cubic, or a combination of both forms. Notably, cubic Rashba spin-orbit coupling induces a distinct triple spin winding on the Fermi surface, differentiating it from linear Rashba spin-orbit coupling. In this Letter, we investigate the potential for two-dimensional topological superconductivity in an interacting bilayer Rashba spin-orbit coupled system with local inversion symmetry breaking. We discover an intriguing interplay between the unique spin texture induced by cubic Rashba spin-orbit coupling and odd-parity Cooper pairing mechanisms. This interplay leads to a mirror symmetry-protected topological crystalline superconductor hosting three pairs of Majorana edge modes associated with an effective helical $f$-wave Cooper pairing. The bulk topology of the helical $f$-wave superconductor is characterized by a mirror Chern number $n_M=3$, which remains stable even in the presence of coexisting linear and cubic Rashba spin-orbit couplings. Our work not only proposes an approach to engineering topological mirror superconductors but also uncovers a pathway to realizing rare helical $f$-wave pairing., Comment: Comments are welcome

Higher-order topological insulators harbor unique corner modes that hold immense potential for applications in information storage. However, the practical manipulation of these states has been constrained by the fixed positions and energies of conventional corner modes. In this work, we present a theoretical framework for generating topologically protected corner-like modes in higher-order topological insulators, exhibiting unprecedented tunability in their positions. These corner-like modes are characterized by a quantized generalized quadrupole moment, indicative of the presence of fractional charges. Moreover, we demonstrate the remarkable ability to modulate the energy of these topological corner modes. Our findings pave the way for the controlled manipulation of corner modes in higher-order topological insulators, opening up new avenues for their applications in advanced information technologies.

Recent studies have attracted widespread attention on magnet-superconductor hybrid systems with emergent topological superconductivity. Here, we present the Floquet engineering of realistic two-dimensional topological nodal-point superconductors that are composed of antiferromagnetic monolayers in proximity to an s-wave superconductor. We show that Floquet chiral topological superconductivity arises naturally due to light-induced breaking of the effective time-reversal symmetry. More strikingly, we find that the Floquet chiral topological superconducting phases can be flexibly controlled by irradiating elliptically polarized light, with the photon-dressed quasi-energy spectrum carrying different Chern numbers. Such optically switchable topological transition is attributed to the simultaneous creations (or annihilations) of valley pairs. Our findings provide a feasible approach for achieving the Floquet chiral topological superconductivity with flexible tunability, which would draw extensive attention in experiments.

In two-dimensional topological nodal superconductors, Majorana edge states have been conventionally believed to exhibit only spin-triplet pairing correlations. However, we reveal a substantial spin-singlet pairing component in Majorana edge states of antiferromagnetic topological nodal-point superconductors. This unexpected phenomenon emerges from the interplay between antiferromagnetic order and symmetry, resulting in Majorana edge states with a nearly flat band dispersion, deviating from the strictly flat band. Crucially, this phenomenon is detectable through spin-selective Andreev reflection, where the zero-bias conductance peaks are maximized when the spin of incident electrons is nearly antiparallel to that of Majorana edge excitations. This discovery unveils a unique spin signature for Andreev reflection resonances, advancing our fundamental understanding of spin-dependent mechanisms in topological superconductivity and representing a significant step towards the experimental detection of Majorana fermions., Comment: 6 pages, 3 figures

Starting from more than 11,200 short-period (less than 0.5 days) EW-type eclipsing binary candidates with the All-Sky Automated Survey for Supernovae (ASAS-SN) V-band light curves, we use MCMC and neural networks (NNs) to obtain the mass ratio ($q$), orbital inclination ($incl$), fill-out factor ($f$) and temperature ratio ($T_s/T_p$). After cross-matching with the Gaia DR3 database, the final sample contains parameters of 2,399 A-type and 8,712 W-type contact binaries (CBs). We present the distributions of parameters of these 11,111 short-period CBs. The mass ratio ($q$) and fill-out factor ($f$) are found to obey log-normal distributions, and the remaining parameters obey normal distributions. There is a significant period-temperature correlation of these CBs. Additionally, the temperature ratio (${T_s}$/${T_p}$) tends to increase as the orbital period decreases for W-type CBs. There is no significant correlation between them for A-type CBs. The mass ratio and fill-out factor ($q-f$) diagram suggest there is no significant correlation between these two parameters. A clear correlation exists between the mass ratio and radius ratio. The radius ratio increases with the mass ratio. Moreover, the deep fill-out CBs tend to fall on the upper boundary of the $q$$-$${R_s}$/${R_p}$ distribution, while the shallow fill-out CBs fall on the lower boundary., Comment: 15 pages, 8 figures, 1 table.Accepted for publication in ApJS. The full dataset will be available with the ApJS article

In crystalline systems, higher-order topology, characterized by topological states of codimension greater than one, typically arises from the mismatch between Wannier centers and atomic sites, leading to filling anomalies. However, this phenomenon is less understood in aperiodic systems, such as quasicrystals, where Wannier centers are not well defined. In this study, we examine Fibonacci chains and squares, a quintessential type of quasicrystal, to investigate their higher-order topological properties. We discover that topological interfacial states, including corner states, can be inherited from their higher-dimensional periodic counterparts, such as the two-dimensional Su-Schrieffer-Heeger model. This finding is validated through numerical simulations of both phononic and photonic Fibonacci quasicrystals by the finite element method, revealing the emergence of topological edge and corner states at interfaces between Fibonacci quasicrystals with differing topologies inherited from their parent systems. Our results not only provide insight into the higher-order topology of quasicrystals but also open avenues for exploring novel topological phases in aperiodic structures., Comment: 9 pages, 6 figures

Higher-order nodal line semimetals represent a recently proposed topological semimetal class that harbors bulk nodal lines and features gapless hinge Fermi arc excitations, governed by the bulk-hinge correspondence. In this study, we investigate the disorder effect on a higher-order nodal line semimetal and the consequent phase transitions. Within the pristine higher-order nodal line semimetal model, we unveil three distinct phases: higher-order nodal line semimetal, conventional nodal line semimetal, and normal insulator. The higher-order nodal line semimetal is characterized by one-dimensional hinge Fermi arc states connecting a pair of nodal rings, contrasting with conventional nodal line semimetals that exhibit two-dimensional drumhead surface states. We demonstrate that disorder can trigger multiple phase transitions within this system. Significantly, intermediate disorder can induce higher-order topology in an initial conventional nodal line semimetal or even an initial normal insulator. Further increase in disorder drives the system through a diffusive metallic phase before ultimately reaching the Anderson insulator regime. Employing a combination of finite-size scaling analysis and an effective medium theory, we construct a comprehensive phase diagram, elucidating the intricate interplay between disorder and topology., Comment: 8 pages, 9 figures.Comments are welcome

Topological superconductors are a class of unconventional superconducting materials featuring sub-gap zero-energy Majorana bound modes that hold promise as a building block for topological quantum computing. In this work, we study the realization of second-order topology that defines anomalous gapless boundary modes in a two-orbital superconductor with spin-orbital couplings. We reveal a time-reversal symmetry-breaking second-order topological superconducting phase with $d+id$-wave orbital-dependent paring without the need for the external magnetic field. Remarkably, this orbital-active $d$-wave paring gives rise to anomalous zero-energy Majorana corner modes, which is in contrast to conventional chiral $d$-wave pairing, accommodating one-dimensional Majorana edge modes. Our work not only reveals a unique mechanism of time-reversal symmetry breaking second-order topological superconductors but also bridges the gap between second-order topology and orbital-dependent pairings., Comment: 5+ pages, 5 figures

Quantum anomalous Hall (QAH) insulators with high Chern number host multiple dissipationless chiral edge channels, which are of fundamental interest and promising for applications in spintronics and quantum computing. However, only a limited number of high-Chern-number QAH insulators have been reported to date. Here, we propose a dynamic approach for achieving high-Chern-number QAH phases in periodically driven two-dimensional higher-order topological insulators (HOTIs).In particular, we consider two representative kinds of HOTIs which are characterized by a quantized quadruple moment and the second Stiefel-Whitney number, respectively. Using the Floquet formalism for periodically driven systems, we demonstrate that QAH insulators with tunable Chern number up to four can be achieved. Moreover, we show by first-principles calculations that the monolayer graphdiyne, a realistic HOTI, is an ideal material candidate. Our work not only establishes a strategy for designing high-Chern-number QAH insulators in periodically driven HOTIs, but also provides a powerful approach to investigate exotic topological states in nonequilibrium cases., Comment: 6 pages, 3 figures

The existence of fractionally quantized topological corner states serves as a key indicator for two-dimensional second-order topological insulators (SOTIs), yet has not been experimentally observed in realistic materials. Here, based on effective model analysis and symmetry arguments, we propose a strategy for achieving SOTI phases with in-gap corner states in two dimensional systems with antiferromagnetic (AFM) order. We uncover by a minimum lattice model that the band topology originates from the interplay between intrinsic spin-orbital coupling and interlayer AFM exchange interactions. Using first principles calculations, we show that the 2D AFM SOTI phases can be realized in (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_{m}$ films. Moreover, we demonstrate that the nontrivial corner states are linked to rotation topological invariants under three-fold rotation symmetry $C_3$, resulting in $C_3$-symmetric SOTIs with corner charges fractionally quantized to $\frac{n}{3} \lvert e \rvert $ (mod $e$). Due to the great recent achievements in (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_{m}$ systems, our results providing reliable material candidates for experimentally accessible AFM higher-order band topology would draw intense attentions., Comment: 7 pages, 4 figures

Three-dimensional higher-order topological semimetals in crystalline systems exhibit higher-order Fermi arcs on one-dimensional hinges, challenging the conventional bulk-boundary correspondence. However, the existence of higher-order Fermi arc states in aperiodic quasicrystalline systems remains uncertain. In this work, we present the emergence of three-dimensional quasicrystalline second-order topological semimetal phases by vertically stacking two-dimensional quasicrystalline second-order topological insulators. These quasicrystalline topological semimetal phases are protected by rotational symmetries forbidden in crystals, and are characterized by topological hinge Fermi arcs connecting fourfold degenerate Dirac-like points in the spectrum. Our findings reveal an intriguing class of higher-order topological phases in quasicrystalline systems, shedding light on their unique properties.

Recently, an exotic quantum Hall ferromagnet with spin-filtered helical edge modes was observed in monolayer graphene on a high-dielectric constant substrate at moderate magnetic fields, withstanding temperatures of up to 110 Kelvin [L. Veyrat et al., Science 367, 781 (2020)]. However, the characteristic quantized longitudinal resistance mediated by these edge modes departs from quantization with decreasing temperature. In this work, we investigate the transport properties of helical edge modes in a graphene nanoribbon under a perpendicular magnetic field using the Landauer-Buttiker transport formalism. We find that the departure of quantization of longitudinal conductance is due to the helical-edge gap opened by the Rashba spin-orbital coupling. The quantization can be restored by weak nonmagnetic Anderson disorder at low temperature, increasing the localization length, or by raising temperature at weak disorder, through thermal broadening. The resulted conductance is very close to the quantized value 2e2/h, which is in qualitatively consistent with the experimental results. Furthermore, we suggest that the helical quantum Hall phase in graphene could be a promising platform for creating Majorana zero modes by introducing superconductivity., Comment: 7 pages, 5 figures

The diffuse gamma-ray emission between 10 and 1000 TeV from the Galactic plane was recently measured by the Large High Altitude Air Shower Observatory (LHAASO). These observations will help tremendously in constraining the propagation and interaction of cosmic rays in the Milky Way. Additionally, new measurements of CR spectra reach a very high precision up to 100 TeV energies, revealing multiple spectral structures of various species. In this work, we confront the model prediction of the diffuse gamma-ray emission, based on up-to-date measurements of the local cosmic ray spectra and simplified propagation setup, with the measurements of diffuse gamma-rays. To better constrain the low-energy part of the model, we analyze the 14.6 years of Fermi-LAT data to extract the Galactic diffuse emission between 1 and 500 GeV from the same sky regions of LHAASO, after subtracting the contribution from known sources and the isotropic diffuse gamma-ray background. The joint Fermi-LAT and LHAASO spectra thus cover a very wide energy range from 1 GeV to 1 PeV with small gaps from 0.5 to 10 TeV. Compared with the prediction, we find that clear excesses between several GeV and ~60 TeV of the diffuse emission exist. Possible reasons to explain the excesses may include unresolved sources or more complicated propagation models. We illustrate that an exponential-cutoff-power-law component with an index of -2.40 and cutoff energy of ~30 TeV is able to account for such excesses.

Precise measurements of the spectra of secondary and primary cosmic rays are crucial for understanding the origin and propagation of those energetic particles. The High Energy cosmic-Radiation Detection (HERD) facility onboard China`s Space Station, which is expected to operate in 2027, will push the direct measurements of cosmic ray fluxes precisely up to PeV energies. In this work, we investigate the potential of HERD on studying the propagation of cosmic rays using the measurements of boron, carbon, and oxygen spectra. We find that, compared with the current results, the new HERD measurements can improve the accuracy of the propagation parameters by 8\% to 40\%. The constraints on the injection spectra at high energies will also be improved., Comment: 10 pages, 4 figures

Recent studies have attracted intense attention on the quasi-2D kagome superconductors $ A\text{V}_3\text{Sb}_5 $ ($ A = $ K, Rb, and Cs) where the unexpected chiral flux phase (CFP) associates with the spontaneous time-reversal symmetry breaking in charge density wave (CDW) states. Here, commencing from the 2-by-2 CDW phases, we bridge the gap between topological superconductivity (TSC) and time-reversal asymmetric CFP in kagome systems. Several chiral TSC states featuring distinct Chern numbers emerge for an s-wave or a d-wave superconducting pairing symmetry. Importantly, these CFP-based TSC phases possess unique gapless edge modes with mixed chiralities (i.e., both positive and negative chiralities), but with the net chiralities consistent with the Bogoliubov-de Gennes Chern numbers. We further study the transport properties of a two-terminal junction, using Chern insulator or normal metal leads via atomic Green's function method with Landauer-B\"uttiker formalism. In both cases, the normal electron tunneling and the crossed Andreev reflection oscillate as the chemical potential changes, but together contribute to plateau transmissions (1 and 3/2, respectively). These behaviors can be regarded as the signature of a topological superconductor hosting edge states with mixed chiralities., Comment: 6 pages, 4 figures

The condensed-matter realization of chiral anomaly has attracted tremendous interest in exploring unexpected phenomena of quantum field theory. Here, we show that one-dimensional (1D) chiral anomaly (i.e., 1D nonconservational chiral current under a background electromagnetic field) can be realized in a generalized Su-Schrieffer-Heeger model where a single gapless Dirac cone occurs. Based on the topological Thouless pump and anomalous dynamics of chiral displacement, we elucidate that such a system possesses the half-integer quantization of winding number. Moreover, we investigate the evolution of 1D chiral anomaly with respect to two typical types of disorder, i.e., on-site disorder and bond disorder. The results show that the on-site disorder tends to smear the gapless Dirac cone. However, we propose a strategy to stabilize the half-integer quantization, facilitating its experimental detection. Furthermore, we demonstrate that the bond disorder causes a unique crossover with disorder-enhanced topological charge pumping, driving the system into a topological Anderson insulator phase.

Two-dimensional Dirac semimetals with a single massless Dirac cone exhibit the parity anomaly. Usually, such a kind of anomalous topological semimetallic phase in real materials is unstable where any amount of disorder can drive it into a diffusive metal and destroy the half-integer quantized Hall conductivity as an indicator of parity anomaly. Here, based on low-energy effective model, we propose an anisotropic Dirac semimetal which explicitly breaks time-reversal symmetry and carries a half-integer quantized Hall conductivity. This topological semimetallic phase can be realized on a deformed honeycomb lattice subjected to a magnetic flux. Moreover, we perceptively investigate the disorder correction to the Hall conductivity. The results show that the effects of disorder can be strongly suppressed and thereby the nearly half-integer quantization of Hall conductivity can exist in a wide region of disorder, indicating that our proposed anisotropic Dirac semimetal is an exciting platform to investigate the parity anomaly phenomena., Comment: 7 pages, 4 figures

We theoretically study the influence of the $k$-cubic Rashba spin-orbit coupling (SOC) on the correlation effects of magnetic impurities by combining the variational method and the Hirsch-Fye quantum Monte Carlo (HFQMC) simulations. Markedly different from the normal $k$-linear Rashba SOC, even a small cubic Rashba term can greatly alter the band structure and induce a Van Hove singularity in a wide range of energy, thus the single impurity local moment becomes largely tunable. The cubic Rashba SOC adopted in this work breaks the rotational symmetry, but the host material is still invariant under the operations $\mathcal{R}^z(\pi)$, $\mathcal{IR}^z(\pi/2)$, $\mathcal{M}_{xz}$, $\mathcal{M}_{yz}$, where $\mathcal{R}^z(\theta)$ is the rotation of angle $\theta$ about the $z$-axis, $\mathcal{I}$ is the inversion operator and $\mathcal{M}_{xz}$ ($\mathcal{M}_{yz}$) is the mirror reflection about the $x$-$z$ ($y$-$z$) principal plane. Saliently, various components of spin-spin correlation between the single magnetic impurity and the conduction electrons show three- or six-fold rotational symmetry. This unique feature is due to the triple winding of the spins with a $2\pi$ rotation of $\mathbf{k}$, which is a hallmark of the cubic Rashba effect and can possibly be an identifier to distinguish the cubic Rashba SOC from the normal $k$-linear Rashba term in experiments. Although the cubic Rashba term drastically alters the electronic properties of the host, we find that the spatial decay rate of the spin-spin correlation function remains essentially unchanged. Moreover, the carrier-mediated Ruderman-Kittel-Kasuya-Yosida interactions between two magnetic impurities show twisted features, the ferromagnetic diagonal terms dominate when two magnetic impurities are very close, but the off-diagonal terms become important at long distances., Comment: 11 pages, 10 figures

Theoretically, the quantum anomalous Hall effect is characterized by a quantized Hall conductance. However, many experiments only reported the quantization of the Hall resistance, which is accompanied by a non-vanishing longitudinal resistance, resulting in a non-quantized Hall conductance. Meanwhile, the non-vanishing longitudinal resistance features a universal exponential decay with the increase in magnetic field. Such a discrepancy obviously challenges the understanding of the quantum anomalous Hall effect. To this end, we propose that the coupling of chiral edge states, which has not been properly evaluated in the previous theories, hinders the quantization of the Hall conductance, while it maintains the quantization of the Hall resistance. The coupling between the chiral edges states along the opposite boundaries can be assisted by magnetic domains or defects inside the sample bulk, which has been already identified in recent experiments. We demonstrate that the chiral edge state coupling theory works rather well to explain the experimental results in both magnetic topological insulator and moir\'e superlattice systems.

Variable stars play a key role in understanding the Milky Way and the universe. The era of astronomical big data presents new challenges for quick identification of interesting and important variable stars. Accurately estimating the periods is the most important step to distinguish different types of variable stars. Here, we propose a new method of determining the variability periods. By combining the statistical parameters of the light curves, the colors of the variables, the window function and the GLS algorithm, the aperiodic variables are excluded and the periodic variables are divided into eclipsing binaries and NEB variables (other types of periodic variable stars other than eclipsing binaries), the periods of the two main types of variables are derived. We construct a random forest classifier based on 241,154 periodic variables from the ASAS-SN and OGLE datasets of variables. The random forest classifier is trained on 17 features, among which 11 are extracted from the light curves and 6 are from the Gaia Early DR3, ALLWISE and 2MASS catalogs. The variables are classified into 7 superclasses and 17 subclasses. In comparison with the ASAS-SN and OGLE catalogs, the classification accuracy is generally above approximately 82% and the period accuracy is 70%-99%. To further test the reliability of the new method and classifier, we compare our results with the results of Chen et al. (2020) for ZTF DR2. The classification accuracy is generally above 70%. The period accuracy of the EW and SR variables is 50% and 53%, respectively. And the period accuracy of other types of variables is 65%-98%., Comment: 23 pages, 10 figures

The recent reported Glashow resonance (GR) event shows a promising prospect in the test of the Lorentz violation (LV) by the high-energy astrophysical neutrinos (HANs) around the resonant energy. However, since the production source and the energy spectra of HANs are uncertain at present, moderate LV effects may be concealed at the TeV energy-scale. In this paper, we propose the LV Hamiltonian of a special texture which can lead to the decoupling of $\nu_{\mu}$ ($\bar{\nu}_{\mu}$). On the base of the decoupling, a noticeable damping of the GR event rate is shown for the HANs from the source dominated by $\bar{\nu}_{\mu}$, irrespective of the energy spectra of the HANs at Earth. Accordingly, the observation of GR events may bring stringent constraints on the LV and the production mechanism of HANs., Comment: 13pages, 3figures

Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by DAMPE show clear hardenings around $100$ GeV/n, which provide important implications on the production, propagation, and interaction of Galactic cosmic rays. In this work we investigate a number of models proposed in literature in light of the DAMPE findings. These models can roughly be classified into two classes, driven by propagation effects or by source ones. Among these models discussed, we find that the re-acceleration of cosmic rays, during their propagation, by random magnetohydrodynamic waves may not reproduce sufficient hardenings of B/C and B/O, and an additional spectral break of the diffusion coefficient is required. The other models can properly explain the hardenings of the ratios. However, depending on simplifications assumed, the models differ in their quality in reproducing the data in a wide energy range. The models with significant re-acceleration effect will under-predict low-energy antiprotons but over-predict low-energy positrons, and the models with secondary production at sources over-predict high-energy antiprotons. For all models high-energy positron excess exists., Comment: 14 pages, 7 figures. Published version

Floquet engineering, the concept of tailoring a system by a periodic drive, is increasingly exploited to design and manipulate topological phases of matter. In this work, we study periodically driven higher-order topological Dirac semimetals associated with a $k$-dependent quantized quadrupole moment by applying circularly polarized light. The undriven Dirac semimetals feature gapless higher-order hinge Fermi arc states which are the consequence of the higher-order topology of the Dirac nodes. Floquet Weyl semimetal phases with hybrid-order topology, characterized by both a $k$-dependent quantized quadrupole moment and a $k$-dependent Chern number, emerge when illumining circularly polarized light. Such Floquet Weyl semimetals support both hinge Fermi arc states and topological surface Fermi arc states. In addition, Floquet Weyl semimetals with tilted Weyl cones in higher-order topological Dirac semimetals are also discussed. Considering numerous higher-order topological Dirac semimetal materials were recently proposed, our findings can be testable soon., Comment: Accepted for publication as a Letter in Phys. Rev. B

Recently, superconductors with higher-order topology have stimulated extensive attention and research interest. Higher-order topological superconductors exhibit unconventional bulk-boundary correspondence, thus allow exotic lower-dimensional boundary modes, such as Majorana corner and hinge modes. However, higher-order topological superconductivity has yet to be found in naturally occurring materials. In this work, we investigate higher-order topology in a two-dimensional Josephson junction comprised of two $s$-wave superconductors separated by a topological insulator thin film. We found that zero-energy Majorana corner modes, a boundary fingerprint of higher-order topological superconductivity, can be achieved by applying magnetic field. When an in-plane Zeeman field is applied to the system, two corner states appear in the superconducting junction. Furthermore, we also discover a two dimensional nodal superconducting phase which supports flat-band Majorana edge modes connecting the bulk nodes. Importantly, we demonstrate that zero-energy Majorana corner modes are stable when increasing the thickness of topological insulator thin film., Comment: 9 pages, 4 figures

Leptonic mixing patterns are usually extracted on the basis of groups or algebraic structures. In this paper, we introduce an alternative geometric method to study the correlations between the leptonic mixing parameters. At the 3$\sigma$ level of the recent global fit data of neutrino oscillations, the distribution of the scattered points of the angles between the vectors, which are constructed by the element of the leptonic mixing matrix, is analysed. We find that the scattered points are concentrated on several special regions. Using the data in these regions, correlations of the leptonic mixing angles and the Dirac CP violating phase are obtained. The implications of the correlations are shown through the predicted flavor ratio of high-energy astrophysical neutrinos (HANs) at Earth., Comment: 21pages, 13figures

Recently, a type of Hall effect due to an unusual layer-locked Berry curvature called the layer Hall effect (LHE) has been reported in the even-layered two-dimensional antiferromagnetic (AFM) MnBi2Te4 [A. Gao et.al, Nature 595, 521 (2021)]. In this work, we report that the quantization of LHE, which we call the quantum anomalous layer Hall effect (QALHE), can be realized in MnBi2Te4. The QALHE originates from kicking a layer-locked Berry-curvature monopole out of the Fermi sea by a vertielectric cal field. Remarkably, we demonstrate that the electric-field reversal can switch the sign of the quantized Hall conductance of QALHE in the even-layered AFM phase. The QALHE can also be realized in the ferromagnetic phase. These results provide a promising way toward the electric engineering of the Berry curvature monopoles and quantized-layered transport in topological magnets., Comment: 6 pages, 4 figures (+ supplementary materials 6 pages, 4 figures)

The progress of neutrino astronomy makes the precise measurement of the flavor ratio of high energy astronomical neutrinos (HANs) possible in the near future. Then matter effects and new physics effects on the flavor transition of HANs could be tested by the next-generation neutrino telescopes. In this paper we study matter effects in gas around the sources of HANs. The matter effects are dependent on both the decoherence schemes and the sources of neutrinos. We examine the predictions on the flavor ratio at Earth for typical sources with five decoherence schemes. For the adiabatic schemes, the matter effect is notable and may be identified in the special range of the electron density, irrespective of the production sources of HANs. Hence, the precise measurement of the flavor ratio would provide constrains on the propagation schemes and the matter parameter., Comment: 19pages, 10 figures

Search for higher-order topological insulators, characterized by topologically protected gapless boundary states of codimension higher than one, in bosonic systems has attracted growing interest. Here, we establish twisted bilayer honeycomb magnets as a new platform for hosting second-order topological magnon insulators (SOTMIs) without fine-tuning. We employ a simple, minimal Heisenberg spin model to describe misaligned bilayer sheets of honeycomb ferromagnetic magnets with a large commensurate twist angle. We found that the higher-order topology in this bilayer system shows a significant dependence on the interlayer exchange coupling. The SOTMI, featuring topologically protected magnon corner states, appears for ferromagnetic interlayer couplings, while the twisted bilayer exhibits a nodal phase in the case of antiferromagnetic interlayer coupling., Comment: Accepted for publication as a Letter in Phys. Rev. B

Recently,a half-quantized Hall conductance (HQHC) plateau is experimentally observed in a semi-magnetic topological insulator heterostructure. However,the heterostructure is metallic with a nonzero longitudinal conductance, which contradicts the common belief that quantized Hall conductance is usually observed in insulators.In this work,we systematically study the surface transport of the semi-magnetic topological insulator with both gapped and gapless Dirac surfaces in the presence of dephasing process.In particular, we reveal that the HQHC is directly related to the half-quantized chiral current along the edge of a strongly dephasing metal. The Hall conductance keeps a half-quantized value for large dephasing strengths, while the longitudinal conductance varies with Fermi energies and dephasing strengths. Furthermore, we evaluate both the conductance and resistance as a function of the temperature, which is consistent with the experimental results.Our results not only provide the microscopic transport mechanism of the HQHC,but also are instructive for the probe of the HQHC in future experiments., Comment: 10 pages, 7 figures

An unconventional superconductor is distinguished with two types of gap functions: unitary and non-unitary. This core subject has been concentrated on purely spin-triplet or singlet-triplet mixed superconductors. However, the generalization to a purely spin-singlet superconductor has remained primarily of theoretical interest, which requires at least a multi-orbital correlated electronic systems. In this work, we present a possible establishment of both unitary and non-unitary pairings for spin-singlet superconductors with two atomic orbitals. Then we investigate the effects of atomic spin-orbit coupling and find a new spin-orbit-coupled non-unitary superconductor that supports exotic phenomena. Remarkably, there are mainly three features. Firstly, the atomic spin-orbit coupling locks the electron spins to be out-of-plane, which could give birth to the Type II Ising superconductivity with a large in-plane upper critical field compared to the Pauli limit. Secondly, topological chiral or helical Majorana edge state could be realized even in the absence of external magnetic fields or Zeeman fields. In addition, a spin-polarized superconducting state could even be generated by spin-singlet non-unitary pairings with spontaneous time-reversal breaking, which severs as a smoking gun to detect this exotic state by measuring the spin-resolved density of states. Therefore, our work might pave a new avenue to spin-orbit-coupled superconductors with spin-singlet non-unitary pairing symmetries., Comment: 12 pages, 5 figures