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A new material called magnetic-charge ice has been created by physicists in the US. The magnetic properties of the material can be manipulated at the nanometre scale and the material could someday be used to encode data at higher densities than current magnetic memories. The techniques used to create and control the new material could also lead to the realization of other artificial magnetic systems.

 

PW spin ice

 

Water ice has a tetrahedral structure that is distorted such that each hydrogen atom is shifted either towards or away from its nearest oxygen atom. The chemist Linus Pauling postulated in 1935 that, in the lowest energy lattice state, every oxygen atom has two protons shifted towards it and two shifted away. This constraint cannot simultaneously be satisfied everywhere, making ice a frustrated system. For other materials, such as certain mineral crystal lattices, the atomic spins also follow Pauling's ice rules and have been dubbed spin ices.