From up - down to up - left!

The herringbone pattern of nanoscale domains is key to enabling faster switching in ferroelectric materials. For scale, each tiny domain is only about 40 nanometers wide, or roughly 1/2500 the width of an average human hair. Each colored band is made up of many tiny domains. Credits: Ruijuan Xu and Lane W. Martin, UC Berkeley

Ferroelectric materials are nothing really new. You probably have it in your stove under the button you press to ignite the gas. Indeed, when a pressure is applied to the ferroelectric material a current is generated (piezoelectric effect).

Scientists have also been aware that ferroelectric material have a spontaneous polarisation (up and down) that can be changed by applying a tiny voltage. For this reason they are used in transit cards and in RFID tags. They work well for tiny storage where speed is not of the essence and have the great advantage of keeping their polarisation status indefinitely (unlike RAM memory that needs a continuous refresh if you don't like to lose the data).

The problem with ferroelectric material is that the switch time (the time it takes once you applied the voltage to change the polarisation from up to down) is significantly longer than the one it takes a transistor to change its "conductivity" (transistor can be used as amplifier as well as conducting -not conducting devices and the latter is the use inside a computer).

Now, researchers at UC Berkeley have discovered that the metallic atom (the one that flips up and down) contained in a sort of oxygen cage made by 6 oxygen atoms can also be made to turn from up to left, and from left to down, and from down to back and so on... And this does provide extra "state" that can be useful to store more than one bit but also, and more important, the turn from up to left is twice as fast as the turn from up to down. This increase in speed would make ferroelectric material interesting as a substitute of transistor in a computer.

Now, don't hold your breath. From the demonstration in a lab that something is feasible to an industrial production process that makes it economically viable there is a very huge gap. Still, it is interesting to notice how material science keeps progressing and among the thousands of discoveries that are being made every year a few will turn out to be game changer in the next decade.

Author - Roberto Saracco

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