Conducting ferroelectrics may be key to new electronic memory

Apr 25, 2011

(PhysOrg.com) -- Novel properties of ferroelectric materials discovered at the Department of Energy's Oak Ridge National Laboratory are moving scientists one step closer to realizing a new paradigm of electronic memory storage.

A new study led by ORNL's Peter Maksymovych and published in the American Chemical Society's revealed that contrary to previous assumptions, domain walls in ferroelectric materials act as dynamic conductors instead of static ones.

Domain walls, the separation zones only a few atoms wide between opposing states of polarization in , are known to be conducting, but the origin of the has remained unclear.

"Our measurements identified that subtle and microscopically reversible distortions or kinks in the domain wall are at the heart of the dynamic conductivity," Maksymovych said. "The domain wall in its equilibrium state is not a true conductor like a rigid piece of . When you start to distort it by applying an electric field, it becomes a much better conductor."

Ferroelectrics, a unique class of materials that respond to the application of an electric field by microscopically switching their polarization, are already used in applications including sonar, medical imaging, fuel injectors and many types of sensors.

Now, researchers want to push the boundaries of ferroelectrics by making use of the materials' properties in areas such as and . Gaining a detailed understanding of electrical conductance in domain walls is seen as a crucial step toward these next generation applications.

"This study shows for the first time that the dynamics of these defects - the domain walls - are a much richer source of memory functionality," Maksymovych said. "It turns out you can dial in the level of the conductivity in the domain wall, making it a tunable, metastable, dynamic memory element."

The domain wall's tunable nature refers to its delayed response to changes in conductivity, where shutting off an does not produce an immediate drop in conductance. Instead, the domain wall "remembers" the last level of conductance for a given period of time and then relaxes to its original state, a phenomenon known as memristance. This type of behavior is unlike traditional electronics, which rely on silicon transistors that act as on-off switches when electric fields are applied.

"Finding functionality intrinsic to nanoscale systems that can be controlled in a novel way is not a path to compete with silicon, but it suggests a viable alternative to silicon for a new paradigm in electronics," Maksymovych said.

The ORNL-led team focused on bismuth ferrite samples, but researchers expect that the observed properties of domain walls will hold true for similar materials.

"The resulting memristive-like behavior is likely to be general to ferroelectric in semiconducting ferroelectric and multiferroic materials," said ORNL co-author Sergei Kalinin.

The samples used in the study were provided by the University of California at Berkeley. Other authors are ORNL's Arthur Baddorf, Jan Seidel and Ramamoorthy Ramesh of Lawrence Berkeley National Laboratory and UC Berkeley, and Pennsylvania State University's Pingping Wu and Long-Qing Chen.

Explore further: Scientists use simple, low cost laser technique to improve properties and functions of nanomaterials

Related Stories

Domain walls that conduct electricity

Jan 29, 2009

The logic and memory functions of future electronic devices could shrink dramatically - to one or two nanometers (billionths of a meter) instead of the many tens of nanometers that characterize today's most ...

Small and stable ferroelectric domains

Mar 28, 2011

Researchers are one step closer to figuring out a way to make nano-sized ferroelectric domains more stable, reports a new study in journal Science.

New Path To Solar Energy Via Solid-State Photovoltaics

Mar 30, 2010

(PhysOrg.com) -- Berkeley Lab researchers have found a new mechanism by which the photovoltaic effect can take place in semiconductor thin-films. This new path to energy production brightens the future for ...

Reverse Chemical Switching of a Ferroelectric Film

Feb 25, 2009

(PhysOrg.com) -- 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 ...

Electric Switches Hold Promise for Data Storage

May 22, 2009

(PhysOrg.com) -- Multiferroics are materials in which unique combinations of electric and magnetic properties can simultaneously coexist. They are potential cornerstones in future magnetic data storage and ...

Recommended for you

PPPL studies plasma's role in synthesizing nanoparticles

3 hours ago

DOE's Princeton Plasma Physics Laboratory (PPPL) has received some $4.3 million of DOE Office of Science funding, over three years, to develop an increased understanding of the role of plasma in the synthesis ...

First ab initio method for characterizing hot carriers

Jul 17, 2014

One of the major road blocks to the design and development of new, more efficient solar cells may have been cleared. Researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) have developed ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

holoman
5 / 5 (1) Apr 25, 2011
Ferroelectric / Multiferrics are molecular switches at
~3-5nm in size and can switch less than 300 picoseconds.

By programing the center binary dipole position of the molecule it is possible to create meta materials and many thousands of other applications, data storage being one.