Spin ice materials and magnetic monopoles

Synopsis

In 1935 scientists noticed that hydrogen atoms in water ice remain disordered, even if we cool its temperature down to absolute zero. There exist materials called spin ices in which the magnetic ions’ locations are highly analogous to the location of hydrogen atoms in water ice. An interesting property of these materials is the existence of magnetic monopoles, also called magnetic charges, inside them. No fundamental particle with a net magnetic charge has ever been observed, so these monopoles are not fundamental particles but quasiparticles. Quasiparticles are the collective behavior of real particles inside a solid that can be mathematically interpreted as a single particle that has position and momentum. The existence of these monopoles was reported in 2009, and their properties resemble the properties of hypothetical magnetic monopoles postulated to exist in the vacuum. Researchers recently designed the first 3D artificial spin ice lattice hosting unbound magnetic monopoles.