so
really really fascinating excellent
paper published about a week ago now in
science many would consider the most
prestigious journal alongside nature um
this is beautiful beautiful staggering
work the paper is about basically
pushing the limits of our ability to
manipulate magnets and going all the way
down to single atom magnets basically
and um the spin that was put on this in
the in the media was that basically
they've they've reduced the amount of
storage you need for a single magnetic
bit from about a million atoms roughly
down to 12 atoms but it's so much more
than that it's you know you can you can
put the sort of technological spin on it
but importantly this work was done not
only at liquid helium temperatures 4.2
kelvin actually down to half a kelvin
500 milli kelvin that's
unbelievably cold um and also in an
ultra high vacuum so this is not going
to come to a computer to use onto an
ipad or
dvd player or whatever to you anytime
soon
forget about all that what it is it's
just beautiful fundamental science
so what they've done
is they've taken little arrays of atoms
and move them ion atoms they've moved
them around and these atoms are like
basically atomic scale magnets they have
a spin
right we'll have to get into the very
tricky area of spin and magnetism but
before i do that let's let's use a sort
of
these are really really fun if you
haven't got these going get some they're
called the welder neody neodymium
magnets um and they are um
really really quite cool you see that
one just clicked in to form a ring bring
the ends together let's get two on the
table let's get another two here
so let's bring this in you know how much
fun it is to play with magnets but these
are pretty strong magnets so you can see
it's reacting already so you can drag it
up move it around and it up it hops
similarly you can put it under here move
it around so i'm just putting the
magnets under the table
and now the magnetic field can travel
through the wood of the table but you
can you can build up little structures
you can build up a wide range of
different things with these
how does this link into the paper the
reason this links into the paper is well
what
well how do magnets work there is that
classic song that line in that classic
song
by
insane clown posse if i remember
correctly
key thing is that you get a magnetic
field when you're removing charge and
let's think about the smallest moving
charge you can have um which is able to
take the electron and so the electron
has
it acts like a tiny little magnet we see
it's got its it's its magnetic moment
and it can interact with other uh
electrons who are also tiny little
magnets and you've got a north on the
south pole and they can interact but we
call that we couch that
physicists call that spin we call that
electron spin
and the reason was is that back in the
early days of quantum mechanics we're
trying to find ways of connecting these
really weird properties that happen all
the way down in the atomic molecular
level with something that we can get our
heads around in the real world and so
the idea was well okay maybe the
electron
is like a little ball of charge and it
spins around and that spinning round
gives rise to this because you've got a
circulating charge gives rise to a
magnetic moment and you get a tiny
little magnet
problem is
is that if you calculate just the rate
of spin you'd need it's in excess of the
speed of light so that doesn't quite
work for physicists we get this idea in
our head i think we no longer although
we call it spin i don't think very many
physicists who work in this area really
think of it as a spinning electron you
basically think of it as a property and
you almost
certainly the model i have in my head
where's my marker oh i've done one
before is that basically you've got an
electron you're a little born it's got
it's labeled with a spin and it can be
spin up or can be spinned down and those
can interact you have little um
interacting magnets
and that's really
why you can take a fridge magnet and put
it on your door it's because all those
electrons collectively act together
build up a big magnetic field basically
and that allows you to to to um put your
fridge magnet on your door or similarly
allows you to do fun things like this
you can see that that's a rather strong
force but all it's the reason it comes
about
is due to the interactions of electrons
what these guys did was to take
individual ion atoms and ion as you know
is magnetic and the reason it's magnetic
is because it has unpaired electrons so
in the reason so many materials aren't
magnetic is that you have um the
electrons pair up so you've got one
magnet like that one magnet pointing
down again north side south north and
they cancel each other out iron has
unpaired electrons which means it acts
as a little an iron atom acts as a
little magnet so what they've done is
they've taken individual atomic magnets
they've moved them together and they've
measured using something called a
scanning tunneling microscope they've
measured basically the magnetic field
they've measured the magnetic
interaction between the tip and the the
atom at the surface that's remarkable
that's going beyond atomic uh
manipulation other groups have done this
before but not quite in this the the
same way
the the key thing is that not only can
they see the these individual magnets at
the atomic level they can flip them they
can change them and they can see also as
they increase the temperature how these
magnetic domains move around and they
can work out just how small
you
a set of atoms you need to have a stable
magnetic bit
because what happens is that as you warm
things up
um and you make things smaller the
problem is that fluctuations tiny tiny
you know little changes in the
environment
can influence those magnetic spins and
can wash out that magnetic information
what is so impressive about this is that
the ibm mantra is think and so what
they've done here is they've encoded um
in binary um the these letters t-h-i-n-k
and as you can see each one of these
blobs is an individual atom basically
and the blue ones or whether i can't
remember which way around it is but the
blue ones are where the spin the little
magnet points this way and the white
ones are where the magnet points that
way and they can flip these they can
flip these individual atomic magnets so
watch what's an atom in that so an atom
is is one of these blobs basically so
that's where they've um encode they've
got an array of these atoms and what
they've done is they've encoded um
zero one zero one zero zero one one so
what these are the difference between
the red and the blue is the spin state
whether it spins up or the spin zone or
whether magnets pointing north south
that way or not south that way so my
computer over there
and your computer at home the way you
store information on a hard disk is you
exploit these magnetic interactions
these magnetic forces but you do it with
millions and millions and millions of
atoms what these guys have done is
they've scaled it all the way down
they've looked at the fundamental limits
how small can we make a magnetic bit and
more they've gone beyond that they've
looked at well how does temperature
affect this they've looked at well if we
put the atoms in this pattern so they're
stacked up nice and and evenly um does
that give us a stronger magnetic
interactions does that preserve the data
more or if we sort of stagger them a
little bit what i really like about the
ibm work is that it's always so elegant
you read the paper
and you go you go through it now because
they've done that and then questions
arise and you go okay oh right they've
done that as well and then you think
maybe and then every single question you
can think of is in there and it's just
years and years of work and it's just
really really comprehensive really
elegant and that's why the papers always
end up in science and nature because
they are setting the bar
how difficult is it it's unbelievably
difficult you have to get your tip in
the right magnetic state you're working
no in this case not just the
temperatures of a few kelvin you're
working at hundreds of milli kelvin
temperature you're working at pressures
comparable to that you find in
you know in deep space um very very
tricky very very complicated but so much
fun no it's not curing cancer but it's
telling us about the limits of
technology and given us insights into
how we can upgrade our technology and
some of that technology may well go on
to help cure council