Rewritable Wires Could Put an End to Obsolete Circuitry
The Engineer posted on January 11, 2018 | 1119 views
Working towards rewritable nanoscale wires, researchers controlled electrical conductivity in 2-D ferroelectric domain walls by applying a voltage (V). The domain walls behaved like an electric switch. The charges responsible for this behavior were localized to within a few atom widths (a nanometer) of the domain walls, the barriers between regions with different electronic properties, in erbium manganite. In the atomic-resolution electron microscopy image, the positive (red) and negative (blue) polarizations come together in the white region. This polarity mismatch forms a positively charged (head-to-head) domain wall. Applying a voltage added more charge carriers to the domain wall, switching the conductivity of the channel. (Image courtesy of Megan Holtz, Dennis Meier and Emily Falco.)
Working towards rewritable nanoscale wires, researchers controlled electrical conductivity in 2-D ferroelectric domain walls by applying a voltage (V). The domain walls behaved like an electric switch. The charges responsible for this behavior were localized to within a few atom widths (a nanometer) of the domain walls, the barriers between regions with different electronic properties, in erbium manganite. In the atomic-resolution electron microscopy image, the positive (red) and negative (blue) polarizations come together in the white region. This polarity mismatch forms a positively charged (head-to-head) domain wall. Applying a voltage added more charge carriers to the domain wall, switching the conductivity of the channel. (Image courtesy of Megan Holtz, Dennis Meier and Emily Falco.)

Updating, rather than replacing, outdated circuits in tiny sensors would reduce cost and waste. Now, research from the U.S. Department of Energy (DOE) may allow us to do just that.

The unusual electronic properties of ferroelectric domain walls—the interfaces between different types of electrical ordering—are the key. Applying a voltage to the domain wall can change the preferred electrical ordering, making the domain walls move. These walls can be made, moved, and erased on demand, making them promising for next-generation circuit elements.

Advanced electron microscopy allowed the DOE researchers to see that electrons move to the wall to create one-nanometer channels. The electrons that move to the wall were confined to just one to two repeating crystalline unit cells in erbium manganite (ErMnO3). Applying a voltage reversibly switches the channel from insulating to conducting, which could be used as the 0’s and 1’s for binary switches in a computer.

Rewriteable domain walls are a promising avenue for extremely small circuitry. Reversibly switching conductivity on and off with an electric field is a critical step towards using these walls in digital devices, including switches, diodes and field-effect transistors.

The DOE team envisions a transistor where the gate is a domain wall itself—and whether you can pass current through the domain wall is controlled by the charges in the domain wall.

The research is published in the journal Nature Materials under the title “Functional electronic inversion layers at ferroelectric domain walls.”

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Source: DOE

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