In Real Science… – ni – mts

Nick Albertini

Research teams led by Sean Giblin at the Rutherford Appleton Laboratory in Chilton and Steven Bramwell at University College London have successfully made the first measurements of magnetricity. Magnetricity consists of currents of magnetic monopoles in the same way thst electricity consists of currents of electrons. Magnetic monopoles have been a long sought-after physical entity. All magnets are dipoles, having a north pole and a south pole. Even atoms are dipolar magnets.
In 1999, Steven Bramwell’s group discovered a material called spin ice, a magnetically disordered crystal. In 2007, a team led by Claudio Castelnovo of Oxford published a theoretical paper that predicted magnetic monopoles around the size of an atom could exist and propagate in spin ice.
The Castelnovo team suggested that defects in the magnetic orientation of atoms in the spin ice could generate propagating monopoles. These monopoles are not particles like electrons, but instead carry a magnetic charge in much the same way that an electric field can have propagating “holes” of positive charge.
Bramwell then thought to accelerate these monopolar magnetic charges using a magnetic field in order to measure the resultant magnetricity. Bramwell teamed up with Giblin in order to use his muon spectrometer, a device capable of detecting atom-sized magnetic fields. Using this muon spectrometer, they succeeded in detecting magnetricity in spin ice excited by a magnetic field.
The really neat aspect of magnetricity in spin ice, other than the complete novelty of the entire process, is that the charge strength of the magnetic monopoles can be made to vary. Both pressure and temperature affect their magnetic charge. This is a property that electricity does not have. The charge carrier of electricity is an elementary particle with an invariable quantum charge.
In a simple sense, it is like comparing digital to analog. This difference could become a key advantage in the newly coined and up-and-coming field of magnetronics. That’s right! These scientists and, I would imagine, scientists all over the world are now interested in working out how to use this newfound wonder of magnetricity for computation, memory storage and other applications that parallel and intersect with electronics technology.
The ability to finely tune the strength of the charge carrier in such magnetronics could give them distinctly advantageous properties impossible in electronics. Who knows what kind of cool devices that could lead to? Move over Ben Franklin!