A new research on the innovative characteristics of ferroelectrics made at the Department of Energy's Oak Ridge National Laboratory (ORNL) has revealed the source of dynamic conductivity of the domain walls of ferroelectrics.
The research team was headed by Peter Maksymovych and their findings were published in the Nano Letters of American Chemical Society.
Domain walls are the divisional areas between contrasting polarization states in ferroelectric substances. The domain walls are known to be conductors, yet their source of the conductivity has not been understood. Maksymovych has stated that their measurements recognized that mild and microscopically reversible deformations present in the domain wall offer dynamic conductivity to the walls. He added that the domain wall does not serve as an ideal conductor when placed in its equilibrium position. When an electric field is applied, it gets deformed and turns out to be a dynamic conductor.
Ferroelectrics are a novel group of materials that react to electric field by altering their polarization microscopically. They are used in several applications like medical imaging, sensors, fuel injectors and sonar. Scientists are working on deploying ferroelectric materials in fields like nanoelectronics and memory storage. Obtaining a comprehensive understanding regarding conductivity of domain walls is a critical footstep towards improving these applications.
Maksymovych has mentioned that their research has revealed for the first time that the dynamics of domain walls serves as a major origin of the performance of memory. He added that the tunable conductivity level in the domain wall can serve as a dynamic memory element.
The adaptability of the domain wall signifies its deferred reaction to variations in conductivity and closing down an electric filed does not result in a sudden fall in conductance. The previous conductance level will be remembered by the domain wall for a particular span of time, followed by relaxation to its initial state. This type of behavior is termed as memristance. Conventional electronics depends on silicon transistors that serve as on-off switches during the application of electric fields.
According to Maksymovych, their new breakthrough discovery in electronics offers a possible substitute to silicon and will not serve as a path to contend with silicon. The research team worked on samples of bismuth ferrite and they hope that the discovered characteristics of the domain walls will be same for other ferroelectric materials as well. Sergei Kalinin, ORNL Co-author, has stated that the memristive phenomenon is expected to be common in ferroelectric domain walls of multiferroics as well as semiconducting ferroelectrics.
The bismuth ferrite samples used by the researchers were supplied by the University of California. Other authors of the research include Arthur Baddorf of ORNL, Lawrence Berkeley National Laboratory’s Jan Seidel, Lawrence Berkeley National Laboratory’s Ramamurthy Ramesh and Pingping Wu and Long-Qing Chen of Pennsylvania State University.
Source: http://www.ornl.gov