Formation of High Temperature Superconducting Balls

High- $T_c$ superconducting particles of $\mu \mathrm{m}$ size in a strong electric field bind themselves together to form macroscopic balls in milliseconds. Each ball holds over ${10}^6$ particles and bounces between the electrodes without losing any. The ball formation is a result of superconductivity. As the $c$-axis coherence length is shorter than the Thomas-Fermi screening length, the electric field produced by the charged surface layer turns off the coupling between the interlayers. This loss of Josephson energy becomes a positive surface energy induced by the charged surface layer, the minimization of which leads to the balls.