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Menglei Li

Publications and source records attributed to Menglei Li.

8 recordsLinked to original sources

Steering topology distributions for unified generative design of architected metamaterials

Architected metamaterials derive their functions from structure, creating vast opportunities to program physical responses through topology design. However, existing design methods are often tailored to individual design problems, making limited use of topology knowledge for effective and broadly applicable design as objectives, constraints, and physical functions change. Here we introduce Generative Topology Optimization (GenTO), a unified framework that turns a learned topology prior into a reusable design engine. GenTO trains a diffusion model on a large full-order topology dataset and then iteratively steers the resulting topology distribution toward task-specific high-performing regions using user-defined physical objectives and constraints. This shifts the object of optimization from a single structure to a task-adapted topology distribution. Across topology design problems spanning thermal extremization, multi-objective morphology control, property-targeted auxetic design, and vibration transmission design, GenTO reuses pretrained topology priors for heterogeneous tasks, preserves structural diversity, and reaches high-performing solutions supported by numerical benchmarks and experimental validation. These results establish reusable topology knowledge as a unified principle for effective and scalable architected metamaterial design.

cs.AI

Self-consistent clustering analysis for homogenisation of heterogeneous plates

This work introduces a reduced-order model for plate structures with periodic micro-structures by coupling self-consistent clustering analysis (SCA) with the Lippmann-Schwinger equation, enabling rapid multiscale homogenisation of heterogeneous plates. A plate-specific SCA scheme is derived for the first time and features two key elements: (i) an offline-online strategy that combines Green's functions with k-means data compression, and (ii) an online self-consistent update that exploits the weak sensitivity of the reference medium. The framework handles both linear and nonlinear problems in classical plate theory and first-order shear deformation theory, and its performance is verified on linear isotropic perforated plates and woven composites, as well as on non-linear elasto-plastic perforated plates and woven composites with damage. Across all cases the proposed model matches the accuracy of FFT-based direct numerical simulation while reducing computational cost by over an order of magnitude.

physics.comp-ph

Scaling Laws Governing the Elastic Properties of 3D-Graphenes

In this study, we have comprehensively investigated the scaling law for elastic properties of three-dimensional honeycomb-like graphenes (3D-graphenes) using hybrid neural network potential based molecular dynamics simulations and theoretical analyses. The elastic constants as functions of honeycomb hole size, denoted by the graphene wall length $L$, were provided. All five independent elastic constants in the large $L$ limit are proportional to $L^{-1}$. The associated coefficients are combinations of two-dimensional graphene's elastic constants. High-order terms including $L^{-2}$ and $L^{-3}$ emerge for finite $L$ values. They have three origins, the distorted areas close to the joint lines of 3D-graphenes, the variation of solid angles between graphene plates, and the bending distortion of graphene plates. Significantly, the chirality becomes essential with the decreasing of $L$, because the joint line structures are different between the armchair and zigzag type 3D-graphenes. Our findings provide insights into the elastic properties of graphene-based superstructures and can be used for further studies on graphene-based materials.

cond-mat.mtrl-sci

Interlayer magnetic interactions and ferroelectricity in $\pi$/3-twisted CrX$_2$ (X = Se, Te) bilayers

Recently, two-dimensional (2D) bilayer magnetic systems have been widely studied. Their interlayer magnetic interactions play a vital role in the magnetic properties. In this paper, we theoretically studied the interlayer magnetic interactions, magnetic states and ferroelectricity of $\pi$/3-twisted CrX$_2$ (X = Se, Te) bilayers ($\pi$/3-CrX$_2$). Our study reveals that the lateral shift could switch the magnetic state of the $\pi$/3-CrSe$_2$ between interlayer ferromagnetic and antiferromagnetic, while just tuning the strength of the interlayer antiferromagnetic interactions in $\pi$/3-CrTe$_2$. Furthermore, the lateral shift can alter the off-plane electric polarization in both $\pi$/3-CrSe$_2$ and $\pi$/3-CrTe$_2$. These results show that stacking is an effective way to tune both the magnetic and ferroelectric properties of 1T-CrX$_2$ bilayers, making the 1T-CrX$_2$ bilayers hold promise for 2D spintronic devices.

cond-mat.mtrl-sci

Two-dimensional ferromagnetic-ferroelectric multiferroics in violation of the d0 rule

Contribution of d-electron to ferroelectricity of type-II multiferroics causes strong magneto-electric coupling and distinguishes them from the conventional type-I multiferroics. However, their therein polarization is too small because the ferroelectricity is merely a derivative from the magnetic order. Here we report a new class of multiferroic materials, monolayer VOX2 (X = Cl, Br, and I), which combine the advantages of type-I and type-II multiferroics. Both ferroelectricity and magnetism arise from the same V cation, where the filled d-orbital is perpendicular to an a priori ferroelectric polarization and thus poses no hindrance to ferroelectricity, indicating a violation of the usual d0 rule. This makes the combination of large polarizations and strong magneto-electric coupling possible. Our findings not only add new ferromagnetic-ferroelectric multiferroics, but also point to a unique mechanism to engineer multiferroics.

cond-mat.mtrl-sci

Tunable spin states in two-dimensional magnet CrI3

The recent discovery of ferromagnetic single-layer CrI3 creates ample opportunities for studying fundamental properties of atomically-thin magnets. By using first-principles calculations and model analysis, we show that a lateral strain and/or charge doping can have unexpected effects on the magnetic properties of CrI3. In particular, strain tunes the magnetic order and anisotropy: (1) a compressive strain leads to a phase transition from a ferromagnetic insulator to an antiferromagnetic insulator, while (2) a tensile strain can flip the magnetic orientation from off-plane to in-plane. Interestingly, we find that the phase boundary for the first transition is insensitive to charge doping, whereas that of the second one can be significantly modulated by electron doping.

cond-mat.mes-hall

Electronic and magnetic properties of FeSe$_{0.5}$Te$_{0.5}$ : A first-principles study

The atomic structures, electronic band structures and magnetic properties of monolayer FeSe and FeSe$_{0.5}$Te$_{0.5}$ of different configurations have been systematically investigated via first-principles calculations with the inclusion of spin-orbit coupling (SOC). Three different antiferromagnetic (AFM) orders, including checkerboard order, collinear order and pair-checkerboard order, as well as paramagnetic state have been explored. In monolayer FeSe, collinear AFM order is found to be the most stable order, in accordance with previous investigations. Substituting half Se atoms with Te atoms, the pair-checkerboard AFM order is the ground-state magnetic order in FeSe$_{0.5}$Te$_{0.5}$. Both AFM-ordered FeSe and FeSe$_{0.5}$Te$_{0.5}$ have Dirac-cone-like band structures. SOC has a great influence on the band structures at the Dirac cone. The direction of the magnetic moments (in-plane or out-of-plane) directly determines whether the Dirac cone could be opened by SOC, and the gap values also relate to the specific magnetic structure. Although SOC is stronger in FeSe$_{0.5}$Te$_{0.5}$, the SOC-induced band gaps are either only slightly enlarged or even much shrunk compared with those gaps in FeSe. Due to the symmetry breaking brought by Te-substitution, the band structures of FeSe$_{0.5}$Te$_{0.5}$ have a new feature of combined Rashba-Dresselhaus splitting. Our results have provided a comprehensive study on the magnetic property of FeSe$_{0.5}$Te$_{0.5}$, which may help to understand the relation between magnetism and the superconductivity in the high-Tc monolayer superconductor.

cond-mat.mes-hall

Non-Ising Character of a Ferroelectric Wall Arises from a Flexoelectric Effect

Using the classic ferroelectric BaTiO$_3$ as an example, we show that the 180 degree ferroelectric domain wall, long considered to be of Ising-type and charge neural, contains both Bloch and Neel type polarization components, and is thus charged. The bound charge density at the wall may reach as high as 10$^6$~10$^7$ Cm$^{-3}$. It is demonstrated that the flexoelectric effect arising from stress inhomogeneity is responsible for the additional Bloch and Neel polarization components. The magnitudes of these additional components are determined by the competing depolarization and flexoelectric fields.

cond-mat.mtrl-sci