Ferroelectric-graphene-based system could lead to improved information processing

June 21, 2013 by David Chandler
Illustration shows the concept behind the chiral ferromagnetic system for storing data. On a strip of ferromagnetic material, there are different "domains" with opposite orientations of the magnetic field — in this depiction, blue regions are "up" and red regions "down." The boundary regions in between are called domain walls (shown in white), and in those regions the orientation shifts from one direction to the other. That shift can take place in one of two ways — clockwise or counterclockwise — depending on the materials used. Credit: Qing Hu

Researchers at MIT have proposed a new system that combines ferroelectric materials—the kind often used for data storage—with graphene, a two-dimensional form of carbon known for its exceptional electronic and mechanical properties. The resulting hybrid technology could eventually lead to computer and data-storage chips that pack more components in a given area and are faster and less power-hungry.

The new system works by controlling waves called . These waves are oscillations of electrons confined at interfaces between materials; in the new system the waves operate at . Such frequencies lie between those of far- and microwave , and are considered ideal for next-generation computing devices.

The findings were reported in a paper in Applied Physics Letters by associate professor of mechanical engineering Nicholas Fang, postdoc Dafei Jin and three others.

The system would provide a new way to construct interconnected devices that use , such as fiber-optic cables and photonic chips, with electronic wires and devices. Currently, such interconnection points often form a bottleneck that slows the transfer of data and adds to the number of components needed.

The team's new system allows waves to be concentrated at much smaller length scales, which could lead to a tenfold gain in the density of components that could be placed in a given area of a chip, Fang says.

The team's initial proof-of-concept device uses a small piece of graphene sandwiched between two layers of the ferroelectric material to make simple, switchable plasmonic waveguides. This work used lithium niobate, but many other such materials could be used, the researchers say.

Light can be confined in these waveguides down to one part in a few hundreds of the free-space wavelength, Jin says, which represents an order-of-magnitude improvement over any comparable waveguide system. "This opens up exciting areas for transmitting and processing optical signals," he says.

Moreover, the work may provide a new way to read and write electronic data into ferroelectric memory devices at very high speed, the MIT researchers say.

Dimitri Basov, a professor of physics at the University of California at San Diego who was not connected with this research, says the MIT team "proposed a very interesting plasmonic structure, suitable for operation in the technologically significant [terahertz] range. … I am confident that many research groups will try to implement these devices."

Basov cautions, however, "The key issue, as in all of plasmonics, is losses. Losses need to be thoroughly explored and understood."

In addition to Fang and Jin, the research was carried out by graduate student Anshuman Kumar, former postdoc Kin Hung Fung (now at Hong Kong Polytechnic University), and research scientist Jun Xu. It was supported by the National Science Foundation and the Air Force Office of Scientific Research.

Explore further: Graphene-based terahertz devices: The wave of the future

More information: Paper: "Terahertz plasmonics in ferroelectric-gated graphene" dx.doi.org/10.1063/1.4807762

Related Stories

Graphene-based terahertz devices: The wave of the future

May 2, 2012

People use electromagnetic energy every day … watching television, listening to the radio, popping corn with a microwave, taking an X-ray or using a cellphone. This energy travels in the form of waves, which are widely ...

Scientists first to observe plasmons on graphene

June 20, 2012

With a beam of infrared light, scientists have sent ripples of electrons along the surface of graphene and demonstrated that they can control the length and height of these oscillations, called plasmons, using a simple electrical ...

A breakthrough in plasmonics

June 17, 2013

EPFL scientists have discovered how optical signal transmission can be controlled, paving the way for the integration of plasmonics with conventional electronic circuits.

Recommended for you

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 ...

New sensor sends electronic signal when estrogen is detected

November 24, 2015

Estrogen is a tiny molecule, but it can have big effects on humans and other animals. Estrogen is one of the main hormones that regulates the female reproductive system - it can be monitored to track human fertility and is ...


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.