Monday, December 27, 2010
Discovery Moves Racetrack Memory Closer to Reality
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IBM Researchers revealed a previously unknown aspect of key physics inside Racetrack memory -- a new technology design which stands to improve memory capabilities within mobile phones, laptop computers and business-class servers.
This new class of memory could enable devices to store much more
information - as much as a factor of 100 times greater - while using
much less energy than today's designs.
The Racetrack memory project -- which started in IBM's Research labs
six years ago -- flips the current memory paradigm on its head.
Instead of making computers seek out the data it needs - as is the
case in traditional computing systems - IBM's Racetrack memory
automatically moves data to where it can be used, sliding magnetic
bits back and forth along nanowire "racetracks." This technique would
allow electronic manufacturers to design a portable device capable of
storing all the movies produced worldwide in a given year with room
Digital data is typically stored in magnetic hard disk drives, which
are low-cost but slow due to their moving parts, or in solid state
memory such as Flash memory, which are faster but more expensive.
Racetrack memory aims to combine the best attributes of these two
types of devices by storing data as magnetic regions - also called
domains - in racetracks just a few tens of nanometers wide.
The new understanding, revealed last week in the journal Science,
allows the precise control of the placement of these domains, which
the IBM team has proven can act as nano-sized data keepers that can
not only store at least 100 times more memory than today's
techniques, but can be accessed at much greater speeds. By
controlling electrical pulses in the device, the scientists can move
these domain walls at speeds of hundreds of miles per hour and then
stop them precisely at the position needed -- allowing massive
amounts of stored information to be accessed in less than a billionth
of a second.
In short, the IBM scientists were the first to measure the time and
distance of domain wall acceleration and deceleration in response to
electric current pulses, which is how digital information is moved
and processed in Racetrack memory. This not only gives scientists an
unprecedented understanding and control over the magnetic movements
inside these devices but also advances IBM?s Racetrack memory --
driving it closer to marketplace viability.
"We discovered that domain walls don't hit peak acceleration as soon
as the current is turned on, and that it takes them exactly the same
time and distance to hit peak acceleration as it does to decelerate
and eventually come to a stop," said Dr. Stuart Parkin, an IBM Fellow
at IBM Research - Almaden. "This was previously undiscovered in part
because it was not clear whether the domain walls actually had mass,
and how the effects of acceleration and deceleration could exactly
compensate one another. Now we know domain walls can be positioned
precisely along the racetracks simply by varying the length of the
current pulses even though the walls have mass".
To achieve the densest and fastest possible memory, the domain walls
inside the device must be moved at speeds of hundreds of miles per
hour to atomically precise positions along the tracks. These
timescales (tens of nanoseconds) and distances (micrometers) are
surprisingly long, especially since previous experiments had shown no
evidence for acceleration and deceleration for domain walls driven
along smooth racetracks with current.
For nearly fifty years, scientists have explored the possibility of
storing information in magnetic domain walls, which are the
boundaries between magnetic regions or "domains" in magnetic
materials. Until now, manipulating domain walls was expensive,
complex and used significant power to generate the fields necessary
to do so. In a proof of concept paper in 2008 IBM researchers were
the first to demonstrate the potential of Racetrack memory, showing
how the use of spin momentum considerably simplifies the memory
The details and results of this research effort will be reported in
the December 24, 2010 issue of Science. The paper is titled,
"Dynamics of magnetic domain walls under their own inertia," and is
authored by Luc Thomas, Rai Moriya, Charles Rettner and Stuart Parkin
of IBM Research ? Almaden.