Development of all magnetic active matter

In the world of low Reynolds number, the role of inertia is entirely negligible, which has resulted in the evolution of novel swimming strategies adopted by the microorganisms to overcome the fluidic drag. Inspired by such techniques, we model magnetically actuated helical swimmers as active particles¹. The activity and density of this artificial system can be tuned externally to better understand the evolution of collective behaviour like the swarming/flocking phenomena. In the past, helical swimmers were designed for reciprocal swimming with motility in the form of back-and-forth motion and unspecified directionality. This represents a zero-force, zero-torque active matter system with enhanced diffusion^2,3. Here for the first time⁴, we break the time-reversal symmetry by engineering a suitable magnetic field aided by thermal fluctuations in the surrounding medium. The swimmers can exhibit non-reciprocal swimming with enhanced diffusivities, with activity as a function of the frequency of the external field and a two-parameter space. The experimental results and numerical simulations are in excellent agreement, establishing an all magnetic active matter.