Tohoku (Japan) - While many commercial ventures are searching for ways to improve efficiency in the dominant spin-torque model for Magnetoresistive-RAM (or MRAM), Japanese physicsts have stumbled upon an entirely new approach which uses less power, switches faster and is even easier to manufacture.


The research team at Tohoku University has utilized a property of magnetic domains in a new way. Domains are the pockets within MRAM cells that hold either a charge or a void. And, like tiny magnets, domains have both a north and south pole.

In the currently dominant spin-torque model for MRAM, the ability to read or store a binary 1 or 0 depends on flipping the orientation of the charge in the domain by passing a current through tiny electromagnets nearby. North up means one value, south up means another. To read the data a small current is passed through a lead.

A similar approach is used to read the state of the charge using this new method. However, the manner in which the charge is stored is where the power savings come in.


Iron-based

The team begins with an iron-based semiconductor foundation as the substrate. Atop this they create cells, electrodes and bitlines around the domain. By passing only electricty through the electrodes (not by powering electromagnets), the existing domain charge is altered - albeit slightly at present.

Research has shown that an existing north/south orientation can be shifted by 10 degrees using their method of only passing small quantities of current through the electrode. In this way, the domain is manipulated without an electromagnet, a world's first in this area of research.

The team is also working on a way to power a new type of electrode, or possibly an series of electrodes, which will ultimately spin the domain a full 180 degrees using only electricity. This degree of spin would provide everything necessary to be a consumer-class binary 1/0 storage device. It would also be require much less power than the spin-torque approach, making it even more desirable for mobile devices.


MRAM technology

MRAM has held the enthusist's eye for some years due to its high speed and potential replacement for modern day capacitor-based RAM. Experts believe it will only be a few years before MRAM sees its way into our mainstream PCs, and especially our notebooks, due to its power savings and greater speed.

Even spin-torque MRAM solutions today use much less power than traditional RAM, while also being notably faster. MRAM still remains somewhat difficult to manufacture, though many companies are investing heavily in the technology. They believe it will be one path to greater performance (and therefore greater sources of revenue) in the future.


Recent advancements

Within the past six weeks, an advancement was announced in the spin-torque model. German physicists developed a "pillar design" which greatly reduces cycle times for reads and writes. This new approach is very close to the theoretical limits of the technology in terms of switching speed. And, its reproducible in volume.

This latest model from Japan's represents a fundamental shift in the way the magnetic data is stored within an MRAM cell. In their model, once a charge is initially deposited, only small quantities of current will be required to read and write new values. This will decrease power consumption while increasing performance even more.

here we go again

Sep 25, 2008 15:54     

Nice to see you back Rick! As for the news, how many more articles are we going to see about mram until it is actually useful in the mainstream?
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Magnetic?

Sep 25, 2008 16:15     

What if I come by your computer with magnets while it's working? Yeah, I know, there's the hard disk too, but it's not that affected by magnetic fields...
Meeeee report abuse vote down vote up Votes: -7