Research articles

Understanding the parameters which govern the size of a skyrmion are important to gain greater control over their stability and dynamics but the underlying mechanisms differ from individual skyrmions to skyrmion crystals. To this end, using micromagnetic simulations, the authors theoretically investigate the relationship between the underlying material parameters and skyrmion radius within a skyrmion crystal

Mapping the response required to obtain the desired output field from a metamaterial for a given input remains challenging due to the complexity of scattering processes. Here, a semi-analytical model for the design of aperiodic metasurfaces is presented alongside numerical examples.

Thermodynamic and quantum fluctuations limit the accuracy with which conventional methods can measure observables, often depending on the method chosen. Here, information theory is employed to determine the minimum uncertainty in the resonant frequency of a harmonic oscillator in a method-independent way.

While the presence of spatial heterogeneities is known to affect emergent collective behavior in traditional active systems with metric interactions, its role in active systems with nonmetric interactions is still unclear. Here, the authors study the effect of quenched disorder in active matter with topological interactions, finding that topological interactions preserve long-range order in the presence of spatial heterogeneity, which also enhances the emergence of traveling bands.

A solution to performance related challenges posed by nanoscale field effect transistors is to consider atomically thin impurity layers in Si-based devices however there are many aspects of the conductive properties that are still unknown. Here, the authors develop an open system quantum transport method to investigate the local density electronic states of P-doped Si revealing the role of scattering, thickness and doping density.

Two-dimensional electron gases host topological states such as fractional quantum Hall states, which often compete with correlated insulators formed due to Coulomb interactions, such as the Wigner solid. Here the authors report a re-entrant Wigner solid which forms and melts due to fractional correlations, highlighting the role of particle-hole symmetry for phase competition in the quantum Hall regime.

Sedimentation experiments have shown that gravity can deeply affect bulk phenomena and sedimentation of colloidal mixtures. Here, the authors present a theoretical approach based on sedimentation paths to predict the effect of gravity on the emergence of different sedimentation phases in mixtures of anisotropic colloids.

The scientific ecosystem is characterized by complex multifaceted relationships between institutions, researchers, and their collaborators. In this work, the authors find common patterns in these relationships expressed through superlinear scaling, Heaps’ law, and Zipf’s law within the global collaboration network, and propose a minimal network model to explain these patterns based on preferential hiring by larger institutions, the “adjacent possible” capturing the birth of new institutions, and triadic closure of collaborations.

Node duplication is an established model of network formation, whereby an existing node is duplicated, and edges are formed with uniform probability to the neighbours of the duplicated node. Here, the author proposes a copying model where links are copied depending on hidden interactions between nodes, and shows analytically and numerically that this leads to higher network clustering than in the uniform copying case, a property that is also found in real collaboration networks.

Evaluating the importance of nodes and hyperedges in hypergraphs is relevant to link detection, link prediction and matrix completion. Here, the authors define a family of nonlinear eigenvector centrality measures for both edges and nodes in hypergraphs, propose an algorithm to calculate them, and illustrate their application on real-world data sets.

Understanding heterogeneous topological structures in real-world complex networks is challenged by the difficulty of describing their multifractal nature and inferring their generator rules. Here, the authors present a weighted multifractal graph model as a generative approach for studying the structural properties of complex networks in realistic scenarios where only partial observational data is available or the input network is noisy, and demonstrate it on biological networks.

Controlling active matter represents an exciting avenue for studying collective pattern formation. In this article the authors present optical control of persistent flows of active filaments-motor protein mixtures and show how boundaries determine the architecture of active flows

Wetting of surfaces can be affected by surface roughness, presence of surface chemical defects, or by electric fields. Here, the authors perform electrowetting experiments on microstriped electrodes and show that the droplet’s static contact angle hysteresis can be controlled by an inhomogeneous electric field while remaining isotropic, as does the droplet contact radius.

Recent studies have shown that complex systems are often best represented by generalized networks such as hypergraphs, multilayer networks, and temporal networks. Here, the authors propose a unified framework to investigate cluster synchronization patterns in generalized networks and demonstrate the existence of chimera states that emerge exclusively in the presence of higher-order interactions.

All-optical platforms hold potential for fast and efficient analog computing, but are limited by their size and poor reconfigurability. Here, a zero-index nanophotonic platform enables post-Moore’s law analog optical computing, processing data with high throughput and low-energy levels.

While public space is traditionally shared by pedestrian and cars, the distancing measures imposed by the Covid-19 pandemic have underlined the need for wider pedestrian spaces. Here, the authors take a complex network approach to analyze sidewalk data from cities across the world to evidence a strong unbalance in the space distribution between cars and pedestrian, and propose a strategy to improve urban walkability within a socially distancing context and without compromising road traffic.

Elastocaloric materials exhibit temperature changes under applied stress and could be the basis for an environmentally friendly cooling system if issues with their long term stability can be addressed. Here, the authors design and build an elastocaloric device using evaporation and condensation of a fluid achieving enhanced specific cooling power and long term stability.

Sections of the Large Hadron Collider generate more secondary electrons, which induce heat load problems and limit collider performance. Here, beamline components are examined, surface modifications responsible for enhanced secondary electron emission are identified, and curative solutions are proposed.

The manipulation of spin degree of freedom allows the exploration of novel phenomena at the nanoscale. The authors achieved unprecedented submicroKelvin temperatures in the spin system of nuclei embedded in low dimensional semiconductors. A result that opens the way to the investigation of spin-spin interactions and exotic spin-ordered phases.

The evolution of epidemic outbreaks in urban settings is known to stem from the interplay between demographic, structural, and economical characteristics. Here, the authors combine a data driven approach with meta-population modelling to show that the epidemic vulnerability of cities hinges on the morphology of human flows, and propose how a city’s mobility backbone could be modified to minimize the epidemic risk.