Researchers Discover Surface Orbital 'Roughness' in Manganites

Nov 20, 2007

Researchers at the U.S. Department of Energy's Brookhaven National Laboratory have shown that in a class of materials called manganites, the electronic behavior at the surface is considerably different from that found in the bulk. Their findings, which were published online in the November 18, 2007, issue of Nature Materials, could have implications for the next generation of electronic devices, which will involve increasingly smaller components.

As devices shrink, the proportion of surface area grows in comparison to the material's volume. Therefore, it's important to understand the characteristics of a material's surface in order to predict how those materials behave and how electrons will travel across an interface, said Brookhaven physicist John Hill.

Hill and his fellow researchers were particularly interested in how the outer electrons of atoms in a so-called manganite material are arranged. Manganites - consisting of a rare-earth element such as lanthanum combined with manganese and oxygen - show a huge change in electrical resistance when a magnetic field is applied. Taking advantage of this "colossal magnetoresistance effect" could be the key to developing advanced magnetic memory devices, magnetic field sensors, or transistors.

The research team, which also includes scientists from KEK (Japan), CNRS (France), Ames Laboratory, and Argonne National Laboratory, used x-ray scattering at Brookhaven's National Synchrotron Light Source and Argonne's Advanced Photon Source to study the orbital order - the arrangement of electrons in the outermost shell - of the material at the surface and in its bulk.

"When you cool down the bulk material to a particular temperature, all the orbitals arrange themselves in a very particular pattern," Hill said. "The question is, does the same thing happen at the surface? And if not, how is it different?"

The authors found that at the surface, the orbital order is more disordered than in the bulk material. And, even though the manganite's crystal surface is atomically smooth, the orbital surface is rough. These characteristics could affect the way electrons are transferred across a material's surface and provide fundamental information for future research and development. Next, the researchers plan to look for this surface orbital "roughness" in other materials and test its effect on magnetism.

Source: Brookhaven National Laboratory, by Kendra Snyder

Explore further: Growth of an ultra-thin layered structure offers surprises

add to favorites email to friend print save as pdf

Related Stories

Repaired Opportunity rover readies for 'Marathon Valley'

Sep 17, 2014

With a newly cleared memory, it's time for Opportunity to resume the next stage of its long, long Martian drive. The next major goal for the long-lived rover is to go to Marathon Valley, a spot that (in images ...

Rosetta's lander Philae will target Site J

Sep 15, 2014

(Phys.org) —Rosetta's lander Philae will target Site J, an intriguing region on Comet 67P/Churyumov–Gerasimenko that offers unique scientific potential, with hints of activity nearby, and minimum risk ...

Europe's new age of metals begins

Sep 11, 2014

ESA has joined forces with other leading research institutions and more than 180 European companies in a billion-euro effort developing new types of metals and manufacturing techniques for this century.

Recommended for you

New complex oxides could advance memory devices

Sep 17, 2014

The quest for the ultimate memory device for computing may have just taken an encouraging step forward. Researchers at The City College of New York led by chemist Stephen O'Brien have discovered new complex ...

User comments : 0