Despite the pivotal role of twist in modulating physical properties at van der Waals (vdW) interfaces, the mechanics governing torsional response remain poorly understood. Here, we probe twist mechanics at homo- and heterogeneous vdW interfaces, together with their sliding behaviors within a unified experimental framework. For both systems, the peak torque scales nearly linearly with contact area, in contrast to predictions from linear elastic and rigid models. Remarkably, while the sliding friction of the two interfaces diverges by over three orders of magnitude owing to different scaling laws, the corresponding torque follows the same linear scaling and differs by only about twenty-fold. Large-scale atomistic simulations reveal an edge-dominated yielding mechanism for torsional motion, wherein elastic reconstruction shifts the effective load-bearing region toward the edges, eliminating torque from the contact interior. This mechanism contrasts with the bulk-mediated stress transmission governing translational sliding, a distinction rooted in the different loading geometries inherent to the two motion modes, where torsional loading necessitates perimeter actuation, whereas sliding enables center-driven loading. This symmetry-imposed divergence demonstrates that translational and torsional properties cannot be predicted from one another at vdW interfaces, providing critical insights for the design of dynamically reconfigurable micro- and nanoelectromechanical devices.

Recent studies of two-dimensional layered materials under external electric fields have gained significant attention, as such fields offer a powerful, noninvasive approach to actively modulate surface interactions at the molecular level, enabling real-time and reversible tuning of material properties. In this article, we use fully atomistic molecular dynamics simulations based on machine-learning potentials to predict the dependence of chemifriction on external electric fields in defected layered contacts. By controlling the rate of polar bond formation and rupture, friction can be either increased or decreased depending on the field strength and direction. To extend these atomistic insights to the experimentally relevant low-velocity regime, we develop a physically motivated stochastic model that bridges atomic-scale mechanisms with macroscopic friction behavior. Although demonstrated for hexagonal boron nitride junctions, the proposed mechanism of electrotunable chemifriction is expected to be general and applicable to a broad range of layered materials with polar interlayer bonding.

A dramatic difference between the vertical thermal conductance response of homogeneous and heterogeneous graphene/h-BN interfaces to external mechanical perturbations, is predicted. Homogeneous graphene and h-BN interfaces exhibit strong conductance reduction for both in-plane strain and interfacial twist. Conversely, the vertical thermal conductance of the heterogeneous graphene/h-BN junction is insensitive to twist deformations but shows significant increase or decrease under compressive or tensile strains, respectively. Our atomistic simulations predictions are rationalized by Fermi's golden rule and density of phonon modes analyses, indicating that vertical phonons and local stacking configurations have a central role in the interlayer heat transport behavior. A simple phenomenological model, based on local interlayer distance and stacking, captures well the dependence of vertical heat conductance on strain and twist deformations.

Twistronics of layered materials has emerged as a highly active field due to its profound implications for quantum electronics and materials engineering. However, the controllable manipulation of interlayer stacking remains a significant experimental challenge. Here, the homogeneous contact between hexagonal boron nitride layers is shown to be reproducibly switched between two distinct stable stacking configurations via an externally applied torque. Combining experiments and computational modelling, we identify the stacking order of these stable states as the commensurate AA and AB modes. These two states are associated with different rotational torque maxima, exhibiting an asymmetry ratio of 0.7, and distinct dynamics as a function of the twist angle. Moreover, the peak torque values scale linearly with contact area, highlighting the dominant role of edge elasticity in the twisting process. Given that the AA and AB stacking modes correspond to different out-of-plane electric polarization states, our findings offer a pathway for reconfigurable nano- and micro-electromechanical devices.

We present a spin-uncompensated driven Liouville-von Neumann methodology within the time-dependent density functional theory (DLvN-TDDFT) framework to model collinear electron spin transport in open quantum systems. After introducing and validating the approach, through benchmark simulations of spin-polarized transport in simple molecular junctions, we apply it to a magnetic zigzag graphene nanoribbon junction model under external electric fields. The simulations reveal rich spin-resolved current dynamics, highlighting the DLvN-TDDFT framework as a promising tool for exploring dynamical spintronic phenomena in low-dimensional open quantum systems.

Graphitic polytypes—commensurate stacking variants of graphene layers—exhibit pronounced stacking-dependent properties, including intrinsic polarization, orbital magnetism and unconventional superconductivity. Previous attempts to switch between these polytypes required micrometre-scale domains and micronewton loading forces, severely limiting practical multi-ferroic functionality. Here we demonstrate fully reversible transformations of Bernal tetralayers to rhombohedral crystals down to 30-nanometre-scale dimensions, using <1 nanonewton lateral shear forces and an energy of <1 femtojoule per switching event. We achieve this by inserting an intentionally misaligned spacer, patterned by nanometre-scale cavities, between a pair of aligned bilayers. Within each cavity, the active bilayers sag to form stable single-domain polytypes, whereas outside the cavities, the layers slide freely over superlubric, incommensurate interfaces with ultralow friction. Conducting-probe force-microscopy experiments, supported by force-field calculations, reveal edge-nucleated boundary solitons that slide spontaneously to switch the commensurate domains, indicating ultralow pinning and long-range strain relaxations extending tens of nanometres beyond the islands. By engineering cavity geometries, we program elastic coupling between neighbouring islands and tune switching thresholds and trajectories. This reconfigurable slidetronic control establishes a robust route to multi-ferroic response and elastically coupled switching among distinct stacking states. Superlubric arrays of double-bilayer graphene enable elastically coupled switching between Bernal and rhombohedral graphene polytypes under shear forces below 1 nN with an estimated energy cost of less than 1 fJ per switching event.

Directed motion of nanosurfers, guided by a tribological mechanism, is demonstrated for graphene flakes embedded within a twisted graphene interface. When the flake size matches the moire dimensions, shear-induced superstructure dynamics can anchor the flakes and drive them along directions different than the shear direction. The flake motion can be controlled via the twist angle and the sliding direction. The resulting flake dynamics exhibits two types of stick-slip motion, one at the atomic level and the other on the moire superstructure scale. This phenomenon can be harnessed to design nanomechanical systems for targeted delivery of molecular cargo.

Chiral crystals exhibit useful handedness-dependent properties, including spin selectivity and circularly polarized light sensitivity, yet controlling which enantiomer forms during synthesis remains a central challenge. Existing approaches utilize molecules in solution to template crystal growth, which restricts processing conditions and introduces organic contaminants incompatible with device fabrication. Enantioselective growth of a chiral crystal on a chiral surface via vapor-phase synthesis (chiral epitaxy) has not yet been demonstrated. Here, we show chiral epitaxy of aligned tellurium nanowires on a low-symmetry two-dimensional material, ReSe2. In situ electron microscopies suggest a mechanism where handedness is determined at nucleation by the interface energy difference between Te enantiomers and the chiral substrate surface. Chiral epitaxy provides a solvent-free, vapor-solid route to homochiral crystals compatible with semiconductor and quantum manufacturing processes.

The mechanisms underlying chemifriction (the contribution of interfacial bonding to friction) in defected twisted graphene interfaces are revealed using fully atomistic molecular dynamics simulations based on machine-learning potentials. This involves stochastic events of consecutive bond formation and rupture between single vacancy defects that may enhance friction. A unique shear-induced interlayer atomic transfer healing mechanism is discovered that can be harnessed to design a run-in procedure to restore superlubric sliding. This mechanism should be manifested as negative differential friction coefficients that are expected to emerge under moderate normal loads. A physically motivated phenomenological model is developed to predict the chemifriction effects in experimentally relevant sliding velocity regimes. This allows us to identify a distinct transition between logarithmic increase and logarithmic decrease of the friction force with increasing sliding velocity. While demonstrated for homogeneous graphitic contacts, a similar mechanism is expected to occur in other homogeneous or heterogeneous defected two-dimensional material interfaces.

Chirality-induced orbital-angular-momentum selectivity (CIOAMS) in electron transmission and scattering processes is investigated. Polarization of the OAM of an electron traversing chiral media is first studied via electronic wavepacket propagation using the time-dependent Schrödinger equation. Next, spatial resolution of wavepackets carrying opposite OAM, following scattering from a corrugated surface is demonstrated. This suggests that OAM may play a significant role in the mechanisms underlying chirality induced spin selectivity, measured for electrons crossing chiral media in setups involving Mott polarimetry. Our results highlight the potential to exploit CIOAMS in innovative emerging quantum technologies.

Ferroelectricity in non-centrosymmetrically stacked two-dimensional materials has recently emerged as a highly promising route for designing magnetic-field-free switchable electronic components. Leveraging the anisotropic crystal symmetry, lateral interlayer shifts induce sign changes in their out-of-plane electric polarization-a phenomenon known as slidetronics. In multi-layered stacks, this mechanism facilitates the creation of distinct electric potential steps, paving the way for innovative applications in information technology, including low-power electronics and non-volatile memories. Moreover, the consistent switching behavior unlocks new possibilities for electro- and optomechanical applications. In this talk, I will describe our joint experimental-computationaltheoretical efforts aiming to understand the microscopic origins of the effect, to identify ways to control it, and to extend it to intrinsically apolar materials and to quasi-one-dimensional systems.

Correction for ‘Molecular Aharonov–Bohm-type interferometers based on porphyrin nanorings’ by Chi Y. Cheng et al., Chem. Sci., 2025, 16, 4392–4401, https://doi.org/10.1039/D4SC07992B.

van der Waals heterogeneous interfaces are promising candidates for the scaling-up of structural superlubricity to meet a wide range of applications. Several factors, however, have been identified that may hinder superlubricity. Elasticity is one such intrinsic factor, where shear induced lattice reconstruction leads to local interfacial pinning, even at clean pristine contacts. This introduces intricate energy dissipation mechanisms that are manifested by unconventional frictional scaling laws. Here, through large-scale atomistic simulations, we reveal that the elastic pinning of incomplete moiré tiles at the corners of polygonal sliders dominates kinetic friction up to contact dimensions of hundreds of nanometers, followed by a crossover to edge, and eventually surface dominated frictional regimes. We further demonstrate that slider shape tailoring and twisting allow to control energy dissipation and its scaling with contact size, thus advancing the quest toward achieving large-scale superlubricity.

A goal of molecular electronics and spintronics is to create molecular devices that change their conductance in response to external stimuli. The Aharonov-Bohm (AB) effect implies that an electronic device formed from a quantum ring and metallic leads will exhibit such behavior under external magnetic fields. At first sight, it appears that unrealistically large fields would be required to significantly alter the conductance of a molecular ring. However, the sensitivity of a molecular AB interferometer to magnetic fields can be increased by weakening the coupling between the molecular ring and the metallic leads. An ideal molecular ring for an AB interferometer has a large radius (to encompass a larger fraction of the AB flux quantum), and a small effective mass (high electron mobility) to enhance its response to magnetic fields. Here, we use computational modelling to demonstrate that recently synthesized zinc porphyrin nanorings, with radii of 2-9 nm, could behave as molecular AB interferometers at achievable magnetic field strengths (5-10 T), if weak ring-lead coupling is used. Building on our recently developed semi-empirical approach, which incorporates the effects of finite magnetic fields on the electronic structure, we develop a transport computational platform that allows us to identify sharp Fano resonances in the transmittance probability of porphyrin nanorings that could be exploited to control the current with an applied magnetic field. These resonances are rationalized in terms of a magnetic field-induced delocalization of the molecular orbitals. Our findings indicate that molecular AB interferometry should be feasible with current experimental capabilities.

Structural superlubricity (SSL) at layered material interfaces is an exciting and vibrant field of research, offering vast opportunities to achieve ultralow friction and wear with numerous potential technological applications. At increasing length‐scales, new physical and chemical energy dissipation pathways emerge that threaten to push the system out of the superlubric regime. Physical inhibitors of SSL are primarily associated with in‐plane elasticity, out‐of‐plane corrugation, moiré superlattices, grain boundaries, and lattice defects. Chemical mechanisms that may suppress superlubric behavior include interlayer bonding, wear, and external contaminants. In this article, these and other challenges are reviewed facing the scaling‐up of structural superlubricity, as reflected in recent experimental and theoretical studies. Further perspectives are offered on future directions for realizing and manipulating macroscale superlubricity, outlining technological opportunities that it entails.

The anisotropic nature of layered materials is key to many of their unique physical properties. The design and control of novel layered architectures requires a microscopic understanding of their intra- and inter-layer interactions. Ab initio simulations, based on, e.g., density functional theory, often provide valuable insights regarding their structural, mechanical, dynamical, and electronic properties. However, such calculations are often computationally demanding, thus limiting the treatment to relatively small length and time scales. Classical molecular dynamic simulations, based on physically motivated force-fields, may offer a viable computationally efficient alternative, when parameterized appropriately against ab initio reference data for small model systems. The general strategy usually relies on a separate treatment of intra- and inter-layer interactions. When considering the latter, popular isotropic potentials, such as those presented by Lennard-Jones and Morse, often fail to simultaneously capture binding and sliding physics. Therefore, anisotropic interlayer force fields, based on the Kolmogorov-Crespi scheme, have become the tool-of-choice. In this review, we summarize progress in the field of anisotropic interlayer force field, including the fundamental theoretical framework, parameterization, and representative applications to selected physical properties. We also discuss potential directions for further advancement, based on state-of-the-art developments in simulation technologies.

Refractive materials found in the natural world often exhibit unique structures that result in intriguing physical properties and offer a valuable resource for designing tailored bio-inspired materials. Here, we investigate from first principles the factors that govern the refractive index of metal-amino-acid crystals. We specifically focus on the influence of crystal structure, metal ion inclusion, and spin configuration in phenylalanine- and cysteine-based materials. We find that the inclusion of copper and zinc metal ions in the crystal lattice has an important structural role that directly influences the refractive properties. In addition, the metal ions may contribute significantly to the dielectric response and therefore to the refractive index even within a given structure. Furthermore, in the synthetically available case of phenylalanine-copper we verify the results experimentally. Our results demonstrate the role of the inclusion of metal atoms in biogenic assemblies, emphasizing the potential use of this concept in bio-inspired molecular crystals that offer a flexible platform for the design of novel materials with desired optical features.

Moiré superstructures arising at twisted 2D interfaces have recently attracted the attention of the scientific community due to exotic quantum states and unique mechanical and tribological behaviors that they exhibit. Here, we predict the emergence of chiral distortions in twisted layered interfaces of finite dimensions. This phenomenon originates in intricate interplay between interfacial interactions and contact boundary constraints. A metric termed the fractional chiral area, is introduced to quantify the overall chirality of the moiré superstructure and to characterize its spatial distribution. Despite the equilibrium nature of the discovered energetic and structural chirality effects they are shown to be manifested in the twisting dynamics of layered interfaces, which demonstrates a continuous transition from stick-slip to smooth rotation with no external trigger.

Abstract Spontaneous electric polarization is recently observed in multilayered van der Waals stacked materials, arising from a symmetry breaking in a unit cell with two or more constituent species, or non‐centrosymmetric intra‐layer atom displacement in single‐atom‐species materials. Here, it is shown that even elemental crystals, consisting of one type of atom and composed of non‐polar and centrosymmetric layers, exhibit electric polarization if arranged in an appropriate three‐dimensional architecture. This concept is demonstrated here for mixed‐stacking tetra‐layer polytypes of non‐polar graphene sheets. Surprisingly, it is find that the room temperature out‐of‐plane electric polarization increases with external electrostatic hole doping, rather than decreases with it owing to screening. Using first‐principles calculations, as well as a self‐consistent tight‐binding model, the emergence of polarization is explain in terms of inter‐layer charge rearrangement and the doping dependence in terms of gating‐induced inter‐layer charge transfer. This newly discovered intrinsic polarization may therefore offer new venues for designing the electronic response of graphene‐based polytypes to external fields.