Ferroelectric storage

A team of scientists at two German government laboratories have come up with a new technique that could pave the way for an alternative to flash memory, the solid-state, low-power drive that has already begun to replace traditional hard drives in smartphones, music players and newer laptops.

In a paper published last month in the journal Science, a team from the Jülich Research Center and the Max Planck Institute of Microstructure Physics in Halle showed that they have overcome a previous hurdle in the advancement of ferroelectric storage, which is used in FeRAM (ferroelectric RAM) and some RFID smartcards.

Ferroelectricity is a property of some materials whose electric polarity - positive or negative - can be reversed given the application of an electric field.

FeRAM has been at a disadvantage

FeRAM has lost out to flash memory despite the fact that it is a better technology - its primary advantage is that it can read and write data much more quickly that flash. However, few gadget makers are using it, because FeRAM continues to be more expensive and have a lower storage density, which measures how much data can be stored in a given physical space.

An additional problem was that as storage density increased, it was believed that there would be a physical limit where the ferroelectric property would degrade.

"If the individual dipoles would stand like soldiers then problems arise when you shrink the material, this property would destroy the whole ferroelectric effect," explained Dietrich Hesse, a Max Planck researcher, in an interview with Deutsche Welle. "You would never be able to construct high density from these materials."

In other words, no polarization, no storing your MP3 collection in FeRAM. Hesse and his colleagues, however, have now debunked this theory.

The Planck team collaborated with another team from Jülich, in western Germany, which has a high-resolution electron microscope, capable of observing dipole rotation - the phenomenon that among other things, allows for data storage.

“What we have discovered, [is] that polarization on a nanometre scale can indeed continuously rotate," Hesse said. “So it starts to rotate - each unit [forms a vortex]. And that ferroelectric [effect] will not be anymore like a normal ferroelectric but a vortex style ferroelectric.”

In essence, that means storing data at denser and smaller scales is now possible.

Likely to take years to make it into consumer products

But don't expect mobile phone and computer manufacturers to make the switch immediately, noted Franz Kreupl, a physics professor at Technical University Munich, who was not part of the paper.

“The problem is that if you scale it down to such a low dimension and you attach some wires to this element, then the capacitance to these wires outweighs the capacitance of this small element," he said.

In other words, while this physical limit has now been broken, the internal wires within an FeRAM chip would become so small that they wouldn't even be able to read the electrons as they pass through the chip.

So, while my iPhones probably won't move to FeRAM anytime soon, the Max Planck team says there might be other applications for newer, denser ferroelectrics, like in RFID tags or smart-cards.

Author: Jonathan Gifford, Haale
Editor: Cyrus Farivar