Electricity and magnetism were tied together in the late 1800s by the celebrated James T. Maxwell. However it was noticed very quickly that these formulae were asymmetric. Whereas electricity allows the presence of electrical charge, such as electrons, there was no such analogue for magnetism. Everyday experience (Such as cutting a conventional bar magnet in half, leading to the generation of two new dipole magnets), tells us that magnetic charge (north and south poles) cannot normally be separated. In the 1930s a famous theoretical physicist called Dirac, predicted the existence of single magnetic poles (monopoles), which lead to a widespread search for the proof of their existence (mainly conducted in large central facilities). Recently it has been realized that arranging arrays of nano-magnets in certain geometries (known as artificial spin ice) that builds in a magnetic frustration, allow the nano-magnets to interact in such a way that excitations of this system behave much like magnetic monopoles under certain circumstances. Several research groups have now confirmed the existence of these monopole defects by direct imaging. These monopole defects may allow new devices to be made which rely on magnetic charge, and it may even be possible to realise a magnetic version of electricity - dubbed "magnetricity".
Source: Nature Physics 7, 68-74 (January 2011)
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