A stack of magnetic plates, each magnetized opposite to its neighbor, is like a layered sandwich where electrons move as a single organism. The whole material starts mimicking an axion — a ghost particle that physicists suspect might be dark matter. The axion was originally conceived to solve a puzzle in the Standard Model (the main theory of the micro-world). Calculations showed that the same sandwich can also host a 'double axion'.
Usually magnetic poles are inseparable, like two halves of a whole, but here that rule is broken. If such a material is assembled in a lab, scientists will get a tabletop sandbox for playing with the universe — no telescopes or colliders needed.
The name 'axion' was coined by Frank Wilczek after a laundry detergent — the particle was supposed to 'clean up' the theory of contradictions.
Magnetic monopoles often pop up in science fiction, sometimes as an inexhaustible energy source, sometimes as a superweapon.