IBM Moves Closer to New Class of Memory

SAN JOSE, CA, Apr 10 (MARKET WIRE) --
Computer memory that combines the high performance and reliability of flash
with the low cost and high capacity of the hard disk drive could be closer
than you think, thanks to a team of IBM (NYSE: IBM) scientists.

Watch the video: http://www.youtube.com/watch?v=dJf3z9AfiVM

In two papers published in the April 11 issue of Science, IBM Fellow Stuart
Parkin and colleagues at the IBM Almaden Research Center in San Jose describe
both the fundamentals of a technology dubbed "racetrack" memory as well
as a milestone in that technology. This milestone could lead to electronic
devices capable of storing far more data in the same amount of space than is
possible today, with lightning-fast boot times, far lower cost and unprecedented
stability and durability.

Within the next ten years, racetrack memory, so named because the data
"races"
around the wire "track," could lead to solid state electronic devices -- with no
moving parts, and therefore more durable -- capable of holding far more data
in the same amount of space than is possible today. For example, this technology
could enable a handheld device such as an mp3 player to store around 500,000
songs or around 3,500 movies -- 100 times more than is possible today -- with
far lower cost and power consumption. The devices would not only store vastly
more
information in the same space, but also require much less power and generate
much less heat, and be practically unbreakable; the result: massive amounts
of personal storage that could run on a single battery for weeks at a time and
last for decades.

"It has been an exciting adventure to have been involved with research
intometal spintronics since its inception almost 20 years ago with our work on
spin-valve structures," said Dr. Parkin. "The combination of extraordinarily
interesting physics and spintronic materials engineering, one atomic layer at a
time, continues to be highly challenging and very rewarding. The promise of
racetrackmemory -- for example, the ability to carry massive amounts of
information in your
pocket -- could unleash creativity leading to devices and applications that
nobody has imagined yet."

IBM is no stranger to creating entirely new markets that spring from
exploratory research such as this. Just a few of the many game-changers
invented at
IBM Research include the memory chip, the hard disk drive and the relational
database.

Currently, there are two main ways to store digital information: solid
state
random access flash memory, commonly used in devices such as mobile phones,
music players and digital cameras, and the magnetic hard disk drive, commonly
used in desktop and laptop computers and some handheld devices. While both
classes of storage devices are evolving at a very rapid pace, the cost of
storing a single data bit in a hard disk drive remains approximately 100 times
cheaper than in flash memory. While the low cost of the hard disk drive is
very attractive, these devices are intrinsically slower and, with many moving
parts, have mechanical reliability issues not present in flash technologies.

Flash memory, however, has its own drawbacks -- while it is fast to read
data,
it is slow to write data, and it, too, has a finite lifespan. Flash, can be
reused only a few thousands of times because it eventually breaks because it is
slightly damaged by each use or "rewrite."

Since racetrack memory has no moving parts, and, rather than storing data as
ensemble of electronic charge, uses the "spin" of the electron to store data,
it has no wear-out mechanism and so can be rewritten endlessly without any wear
and
tear.

A closer look at racetrack

For nearly fifty years, scientists have explored the possibility of
storinginformation 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 the paper describing their milestone, "Current
Controlled
Magnetic Domain-Wall Nanowire Shift Register," Dr. Parkin and his team describe
how this long-standing obstacle can be overcome by taking advantage of the
interaction of spin polarized current with magnetization in the domain walls;
this
results in a spin transfer torque on the domain wall, causing it to move. The
use of spin momentum transfer considerably simplifies the memory device since
thecurrent is passed directly across the domain wall without the need for any
additional field generators.

In the review paper that describes the fundamentals of racetrack,
"MagneticDomain-Wall Racetrack Memory," Dr. Parkin and colleagues describe the
use of
magnetic domains to store information in columns of magnetic material (the
"racetracks") arranged perpendicularly or horizontally on the surface of a
silicon wafer. Magnetic domain walls are then formed within the columns
delineating regions magnetized in opposite directions (e.g. up or down)
along a racetrack. Each domain has a "head" (positive or north pole) and a
"tail" (negative or south pole). Successive domain walls along the racetrack
alternate between "head to head" and "tail to tail" configurations. The spacing
between consecutive domain walls (that is, the bit length) is controlled by
pinning sites fabricated along the racetrack.

In their paper, the scientists describe their use of horizontal permalloy
nanowires
to demonstrate the successive creation, motion and detection of domain
walls by using sequences of properly timed nanosecond long spin-polarized
current pulses. The cycle time for the writing and shifting of the domain walls
is
a few tens of nanoseconds. These results illustrate the basic concept of a
magnetic
shift register relying on the phenomenon of spin momentum transfer to move
series of closely spaced domain walls -- an entirely new take on the
decades-old concept of storing information in movable domain walls.

Ultimately, the researchers expect the racetrack to move into the third
dimension (3D) with the construction of a novel 3D racetrack memory
device,a paradigm shift from traditional two-dimensional arrays of transistors
andmagnetic bits found in silicon-based microelectronic devices and hard disk
drives. By moving into the third dimension, racetrack memory stands to open
new possibilities for developing less expensive, faster devices because it is
not
dependant on miniaturization as dictated by Moore's Law.

Racetrack memory: in the fast lane

Dr. Parkin's advances with racetrack memory build on his prior
accomplishments
in memory technologies including the spin valve, and Magnetic Tunnel
Junctions (MTJs) and breakthroughs in magnetic RAM (MRAM).

Racetrack memory encompasses the most recent advances in this realm, the
field of metal spintronics. The spin-valve read head enabled a
thousand-fold increase in the storage capacity of the hard disk drive in the
past decade; the MTJ is in the process of supplanting the spin-valve because of
its
higher signal. MTJs also form the basis of modern MRAM, in which the
magnetic moment of one electrode is used to store a data bit. Whereas MRAM
uses a single MTJ element to store and read one bit, and hard disk drives use
a single spin-valve or MTJ sensing element to read the approximately 100 GB
of data in a modern drive, racetrack memory uses one sensing device to read
10 to 100 bits.

Further understanding of the interaction of spin polarized current with
magnetic moments is essential. "For example, this might allow a reduction in
the
current density needed to manipulate or move domain walls," said Dr. Parkin.
"This would drop the power needed for racetrack further, and enable even
lower power devices. We expect that our exploration of a wide variety of
materials and structures will provide new insight into domain wall dynamics
driven by current, making possible domain wall based memory and even logic
devices that were previously inconceivable. It will not only change the way
we look at storage, but the way we look at processing information. We're moving
into a world that is more data-centric than computing-centric."

For more information about IBM, please visit www.ibm.com

Contact:
Jenny Hunter
IBM
jennyh@us.ibm.com
510-919-5320

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