Fig. 2.

Spinner clustering and diffusion. (A) Normalized radial pair-distribution function $g(r)$ for all spinners (black squares). A clustering can be observed by comparing $g(r)$ for spinners rotating in the same direction (green circles) and counterrotating ones (red diamonds). Inset is a blow-up of the first two peaks. (B) The spinners’ displacement probability distribution function indicates the diffusive ($t=3\text{s}$) and the ballistic regime ($t=0.1\text{s}$). Red lines are least square fits to $\exp (-x^2/4Dt)$. The experimental parameters:$B_0=2.7\text{mT}$, $f_B=60\text{Hz}$, and $S_A=3.5\pm 0.5/{\text{mm}}^{-2}$.