Scientists create 'magnetricity'

15 Oct 2009, 3:34 pm   -   Source: David Shiga, New Scientist
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Individual magnetic 'charges' - equivalent to the north and south poles of a magnet - have been observed inside a crystalline material called spin ice (Image: STFC).

Individual magnetic 'charges' - equivalent to the north and south poles of a magnet - have been observed inside a crystalline material called spin ice (Image: STFC).

The magnetic equivalent of electricity, dubbed 'magnetricity', has been demonstrated for the first time, New Scientist says.

The magnetic equivalent of electricity, dubbed "magnetricity", has been demonstrated experimentally for the first time. Just as the flow of electrons produces electrical current, individual north and south magnetic poles have been observed to roam freely, generating magnetic "current".

The result could lead to the development of "magnetronics", including nano-scale computer memory.

Magnets normally have two poles, north and south, that are inseparable. Cutting a magnet in half only results in each piece developing its own north and south pole. That is true even if one disassembles a magnet all the way down to its individual atoms, since each behaves as a tiny bar magnet with two poles.

But physicists have theorised that magnetic monopoles – individual north and south poles that are not bound in pairs and can move independently of one another – could form inside a crystalline material called spin ice.

Changing patterns

The individual atoms would still have both north and south poles. But patterns in their orientation would propagate through the material and look just like little magnetic poles roaming around. These patterns would effectively be monopoles, as far as any measurements are concerned.

In September, two teams of physicists fired neutrons at spin ices made of titanium-containing compounds chilled close to absolute zero. The behaviour of the neutrons suggested that monopoles were present in the material.

Now, another team has managed to measure the amount of magnetic "charge" on the monopoles and to measure magnetic analogues to electric current for the first time. The team calls the motion and interaction of monopoles "magnetricity".

The experiment, reported in Nature, was led by Steven Bramwell of the London Centre for Nanotechnology in the UK. Bramwell was a member of a team, led by Tom Fennell of the Laue-Langevin Institute in Grenoble, that reported neutron results in September.
Magnetic 'charge'

To get more detailed information on the monopoles than had previously been possible, Bramwell's team injected muons – short-lived cousins of electrons – into the spin ice. When the muons decayed, they emitted positrons in directions influenced by the magnetic field inside the spin ice.

This revealed that the monopoles were not only present but were moving, producing a magnetic current.

It also allowed the team to measure the amount of magnetic charge on the monopoles. It turned out to be about a 5 in the obscure units of Bohr magnetons per angstrom, in close agreement with theory, which predicted 4.6. Unlike the electric charge on electrons, which is fixed, the magnetic charge on monopoles varies with the temperature and pressure of the spin ice.

Shivaji Sondhi of Princeton University in New Jersey, a spin ice researcher who is not a member of Bramwell's team, called the new achievement "a triumph of a bold experimental foray" in an accompanying commentary in Nature. "The experiment itself and the determination of the charge of magnetic monopoles are striking."

Shrinking memory

Data is stored on computer hard discs by magnetising their surfaces in patterns that represent 1s and 0s. Bramwell speculates that monopoles could one day be used as a much more compact form of memory than anything available today, given that the monopoles are only about the size of an atom.

"It is in the early stages, but who knows what the applications of magnetricity could be in 100 years time," he says.

The monopoles in the spin ice are not the same as cosmic monopoles, fundamental magnetic particles theorised to have been forged in the big bang that have never been observed.
 

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Your Comments

Wellcome....

Jack - from Melbourne, 3 years ago

I agree with you Ben. Every scientific advance is in the hands of the big bucks. But this planet is shrinking and the majority of the population is growing bigger and getting less and less. Almost everyday arrive to our shores the "product" of that social injustice. It's so clear and evident that the course of historic changes is about to occur. Nevertheless the intentions of the profiters. Every advance in technology, science or philosophy is an advance for the entire humanity. Be wellcome !!!

Woo Hoo!

Ben Langdale - from Brisbane, 3 years ago

This is absolutely fantastic! Just imagine the implications this could have on the way we all live in the future. Hopefully all the big companies profiting from other energy sources allow it to be utilized by the general public- wouldn't it be great if the maglev train, solar/ tidal and other renewable energy sources were shared with us all instead of just depleting all natural resources so a few can make a lot of money?The brain is the way of the future, not the wallet- keep thinking :)

AWESOME

hi - from Wantirna South, Melbourne, 3 years ago

AWESOME

nice science reporting!

Peter Wallis - from UK, 3 years ago

Great science reporting! I learnt something new; there was more detail than I could cope with; but you said where I could find out more. Fantastic!

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