Effect of simple shear on knotted polymer coils and globules.

We explore the effect of Couette flow on knotted linear polymer chains with extensive molecular dynamics simulations. Hydrodynamic interactions are accounted for using multi-particle collision dynamics. The polymer chain, originally containing a simple trefoil knot at rest, is described by a coarse-grained bead-spring model in a coil or globular state.

Skyrmion flow in periodically modulated channels.

Magnetic skyrmions, topologically stabilized chiral magnetic textures with particlelike properties, have so far primarily been studied statically. Here, we experimentally investigate the dynamics of skyrmion ensembles in metallic thin film conduits where they behave as quasiparticle fluids. By exploiting our access to the full trajectories of all fluid particles by means of time-resolved magneto-optical Kerr microscopy, we demonstrate that boundary conditions of skyrmion fluids can be tuned by modulation of the channel geometry.

Topological comparison of flexible and semiflexible chains in polymer melts with θ-chains.

A central paradigm of polymer physics states that chains in melts behave like random walks as intra- and interchain interactions effectively cancel each other out. Likewise, θ-chains, i.e.

300-Times-Increased Diffusive Skyrmion Dynamics and Effective Pinning Reduction by Periodic Field Excitation.

Thermally induced skyrmion dynamics, as well as skyrmion pinning effects, in thin films have attracted significant interest. While pinning poses challenges in deterministic skyrmion devices and slows down skyrmion diffusion, for applications in non-conventional computing, both pinning of an appropriate strength and skyrmion diffusion speed are key. Here, periodic field excitations are employed to realize an increase of the skyrmion diffusion by more than two orders of magnitude.