Fundamental discovery could lead to better memory chips

March 15, 2011
At the atomic scale, University of Michigan researchers have for the first time mapped the polarization of a cutting-edge material for memory chips. Credit: Chris Nelson and Xiaoqing Pan

( -- Engineering researchers at the University of Michigan have found a way to improve the performance of ferroelectric materials, which have the potential to make memory devices with more storage capacity than magnetic hard drives and faster write speed and longer lifetimes than flash memory.

In ferroelectric memory the direction of molecules' electrical serves as a 0 or a 1 bit. An electric field is used to flip the polarization, which is how data is stored.

With his colleagues at U-M and collaborators from Cornell University, Penn State University, and University of Wisconsin, Madison, Xiaoqing Pan, a professor in the U-M Department of Materials Science and Engineering, has designed a material system that spontaneously forms small nano-size spirals of the electric polarization at controllable intervals, which could provide natural budding sites for the polarization switching and thus reduce the power needed to flip each bit.

"To change the state of a ferroelectric , you have to supply enough electric field to induce a small region to switch the polarization. With our material, such a nucleation process is not necessary," Pan said. "The nucleation sites are intrinsically there at the material interfaces."

To make this happen, the engineers layered a ferroelectric material on an insulator whose crystal lattices were closely matched. The polarization causes large electric fields at the ferroelectric surface that are responsible for the spontaneous formation of the budding sites, known as "vortex nanodomains."

The researchers also mapped the material's polarization with atomic resolution, which was a key challenge, given the small scale. They used images from a sub-angstrom resolution at Lawrence Berkeley National Laboratory. They also developed image processing software to accomplish this.

"This type of mapping has never been done," Pan said. "Using this technique, we've discovered unusual vortex nanodomains in which the electric polarization gradually rotates around the vortices."

Explore further: Shocking: Environmental chemistry affects ferroelectric film polarity the same way electric voltage does

More information: A paper on the research, titled "Spontaneous Vortex Nanodomain Arrays at Ferroelectric Heterointerfaces" is available online at Nano Letters website.

Related Stories

Reverse Chemical Switching of a Ferroelectric Film

February 25, 2009

( -- Ferroelectric materials display a spontaneous electric polarization below the Curie temperature that can be reoriented, typically by applying an electric field. In this study, researchers from Argonne, Northern ...

Magnetic Vortex Switch Leads to Electric Pulse

April 8, 2009

( -- Researchers at the University of Arkansas have shown that changing the chirality, or direction of spin, of a nanoscale magnetic vortex creates an electric pulse, suggesting that such a pulse might be of use ...

Recommended for you

Physicists develop new technique to fathom 'smart' materials

November 26, 2015

Physicists from the FOM Foundation and Leiden University have found a way to better understand the properties of manmade 'smart' materials. Their method reveals how stacked layers in such a material work together to bring ...

Mathematicians identify limits to heat flow at the nanoscale

November 24, 2015

How much heat can two bodies exchange without touching? For over a century, scientists have been able to answer this question for virtually any pair of objects in the macroscopic world, from the rate at which a campfire can ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.