Physics articles from across Nature Portfolio

The standard topological insulator is characterized by an insulating bulk and a conducting boundary, so a three dimensional insulating bulk of a topological insulator has a conducting surface. Recently, this idea was extended to the edges of the surfaces of the three dimensional material as a new topological phase, referred to as a higher-order topological insulator. Here, the authors find evidence of such higher order topological insulator states in tungsten ditelluride using heterostructures composed of tungsten ditelluride and graphene.

Active systems made of self-propelled units are widespread in nature, and Active Brownian particles (ABPs) are one of the simplest such system The authors theoretically and numerically investigate the collective assembly of ABPs finding a new re-entrant phase that enables motility-induced phase separation, which is dependent solely on activity.

Understanding the interaction of active matter with the random environment is relevant to the navigation of living entities within disordered media. This study introduces a minimal model of active particles that are repelled by both each other and the randomly distributed obstacles to reveal new chiral modes of collective patterns as a function of the quenched noise due to the stochastic nature of the environment.