The particles are "semi-Dirac fermions":

Instead of moving forwards in a kind of river of electric current, [the electrons] began to trace out circular trajectories, like eddies in that river. And because they were so cold, they were also susceptible to quantum effects, meaning each acted like a wave that self-reinforced as it flowed around the eddy. These behaviours caused the semi-Dirac fermions to emerge.

Not exactly sure what a "semi-Dirac fermion" is, but it seems like another case of electrons doing weird sh*t at low temperatures.

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