Mini-lecture: Professor Steve Bramwell on 'magnetricity' (UCL)

Uploaded by UCLTV on 04.11.2009

Hello, I'm Steve Bramwell from the London Centre for Nanotechnology at UCL
I'm going to tell you about 'magnetricity',
which is the magnetic equivalent of electricity and a phenomenon that that we
discovered recently.
In electricity, electric charge
flows like a fluid
like water would flow in a hosepipe, so little electrons or
ions in solution or little electric charges like that
flow and have a current.
Now, it's traditionally been thought that there isn't a magnetic equivalent of that,
even though magnetic charge is a familiar concept. For example, the poles of this bar magnet
have an effect of magnetic charge at either end.
But it's been traditionally thought that
magnetic charge doesn't flow
in tiny little packets
like electric charge does.
However, I've been studying
some materials called 'spin ice' material for about 10 years. Here are some crystals
of spin ice in a bottle.
And what we've discovered recently is
that these real materials contain
little atom-sized packets of magnetic charge
that do form currents, just like electricity, and hence we've named
this phenomenon 'magnetricity' in analogy to electricity.
Now this is a very surprising thing because normally
if you
try and create little packets of magnetic charge, say, by chopping this bar magnet in half,
you don't succeed. You simply create
two more bar magnets
with north poles and south poles at either end.
But what happens in the spin ice material is that
there are some very complicated,
what we call many body interactions between all the atoms in the material,
and these have the result of creating
little atom-sized packets of magnetic charge that can then
flow like electricity.
It's a bit like having
individual north and south poles about the size of an atom
that can sort of flow around within the material, and when you put a magnetic field on,
they all set off
and migrate to one end of the sample.
So I guess the million-dollar question is: is magentricity useful for anything?
The answer is that at present, it's not useful for anything, but it is
an interesting curiosity.
Perhaps in the future it could be useful, though, if one thinks of how useful electricity is
and how long
it took to find any uses of electricity
and it's quite plausible that in many years' time, we'll find uses of magnetricity.
Now one of the possible areas where one might be able use is in the
information technology industry, where we already
use magnetic effects to store
and manipulate information.