New phase for storage

University of Arkansas physicists have discovered a new phase in tiny nanodisks and nanorods that may enable researchers to significantly increase memory storage.

University of Arkansas physicists have discovered a new phase in tiny nanodisks and nanorods that potentially may enable researchers to increase memory storage by more than one thousand-fold.

Ivan Naumov, Laurent Bellaiche and Huaxiang Fu reported their findings in the December 9th issue of the journal Nature.

“Our goal is to explore the possibility of using a single nanoparticle to store one data bit,” Naumov said. However, the net polarisation – which is spontaneously formed in bulk materials and is so far the key to storing information – does not normally exist in nanoparticles. Naumov, Bellaiche, and Fu decided to search instead for a new phase in the world of nano-ferroelectrics.

They found that the dipoles in nanomaterials form a new state when the temperature is lowered. The researchers used computer simulations to determine what happens to the nanorods and nanodiscs when they reach this state.

They found that instead of polarisation, the new phase creates what the researchers call a toroid moment, which rotates in a circular fashion like a vortex. These moments can rotate in one direction or another, forming a bi-stable state that is capable of storing information, like polarisation.

However, the toroid moment provides a different kind of order. Unlike polarisation, the toroid moment can exist in tiny nanoparticles, which allows storage of one bit of information in a single particle.

Also, unlike the polarisation state, in which particles influence one another if moved in close proximity, the vortices created by this new phase do not interact strongly with one another. This means they can be packed together in a small space.

“We know that in principle this new finding can increase the memory capacity using nanoparticles, we don’t yet know how long it will take to make the technology a reality,” Fu said.