“eventually they get so far apart that they lose
all memory of each other.” — STEvEN BRaMWEll
‘Magnetricity’ acts like electricity

“Eventually they get so far apart that
they lose all memory of each other,”
says Bramwell. “The dipole splits in half
and becomes two monopoles.”
Some question using the term mono-
pole for a phenomenon that exists only in
spin ice. This term traditionally refers to
cosmic monopoles created during the Big
Bang. “A real monopole would be a mag-
netic charge that would exist in a vacuum,”
says Michael Bonitz of the University of
Kiel in Germany. “What they have is a
complicated condensed
matter system.”

Confined in spin ice, though, these wandering poles do behave much like monopoles. The poles have magnetic charge that closely agrees with theoretical predictions, and the charges’ interactions follow the same law that governs electric charges, Coulomb’s Law.

By Devin Powell

Electricity has a new little sister: magnetricity. A team of physicists in England and France has created magnetic charges — isolated north and south magnetic poles — and induced them to flow in crystals no bigger than a centimeter across. These moving magnetic charges, which behave almost exactly like electrical charges flowing through batteries and biological systems, could one day be useful in developing “ magne-tronic” devices — though what such devices would do is anybody’s guess.

In magnets, poles always come in pairs. No matter how many times you cut a magnet in half, down to the atoms themselves, each piece will always have a north and a south — a dipole.

Currents of magnetricity
are born when north poles
and south poles split up and
move around independently.

But the magnetic molecules that make up a crystalline material called spin ice are arranged in pyramids, so all the poles can’t easily line up pointing in the same direction. Instead, each pyramid tends to have two magnets pointing inward and two pointing outward.

Using brief magnetic pulses, Bramwell and his team developed a way to trigger currents of magnetic charges — “magnetricity” — that last for minutes.

In 2009 Steven Bramwell of University College London found that sometimes a molecule in spin ice squirms and flips. Two poles, a north and a south, are born. The molecule itself stays put, but these ghostly poles, which aren’t actually attached to a physical object, can move around independently of each other as chain reactions of flipping molecules carry them from pyramid to pyramid.

“We apply a magnetic field to create magnetic charges and get them all going the same direction,” says Sean Giblin, a physicist at the Rutherford Appleton Laboratory in England and a coauthor of a paper published online February 13 in Nature Physics.

The creation and slow dissipation of new magnetic charges follows the same principles that govern electrical ions in solutions. And spin ice stores magnetic charge the way capacitors store electricity. Thus Bramwell’s dream for magnetricity to someday spawn “ magnetronics.” But it may take a while. The currents appear only in crystals kept close to absolute zero.

Teeny tiny chips
In the onward march of miniaturiza-
tion, a computer processor that’s
slightly wider than a pollen grain
can perform many of the logic oper-
ations larger computer chips do, a
team of scientists reports february
10 in nature. the device, developed
by researchers from harvard and
the mItre Corp., contains about
500 transistors made from synthe-
sized nanowires. that’s an order of
magnitude more complex than any
previous nanoprocessor, the scien-
tists say. It’s also scalable, allowing
individual modules to be connected
to each other to potentially develop
tiny, low-power nanocontrollers
for miniature robots or medical
devices. — Devin Powell

Hydrogen’s head shot
the lightest atoms on earth have
finally come into view. research-
ers have directly imaged hydrogen
atoms for the first time, two sepa-
rate teams in Japan report online
february 13 in nature materials
and November 5 in applied Physics
express. In the
new snapshots,
the hydrogen
atoms appear
as faint spots.
the darker blobs
are the crystalline solids yttrium
dihydride and vanadium dihydride,
materials that are being devel-
oped as spongelike containers
for storing hydrogen. to spot the
camera-shy hydrogen atoms, each
team developed slightly different
ways of detecting how the materi-
als deflected the electrons in the
beam of a scanning transmission
electron microscope.