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: Desirable defects

Related Stories

In the realm of eternal ice

Apr 23, 2015

On 6 November 2010, the light of the star known as NOMAD1 0856-0015072 in the Cetus constellation dimmed. What had happened? A dwarf planet at the edge of the solar system had moved in front of the distant ...

Vesta—Ceres' little sister

Apr 21, 2015

Only around 60 million kilometres closer to the Sun than Ceres, another large rock is orbiting in the remote asteroid belt: Vesta. Although its diameter of approximately 530 kilometres makes it a bit too ...

Recommended for you

Bringing high-energy particle detection in from the cold

10 hours ago

Radiation detectors, which monitor high-energy particles such as those produced by nuclear decay and cosmic radiation, are being used increasingly in medical imaging, petroleum well logging, astronomy and ...

Artificial muscles created from gold-plated onion cells

10 hours ago

Just one well-placed slice into a particularly pungent onion can send even the most seasoned chef running for a box of tissues. Now, this humble root vegetable is proving its strength outside the culinary ...

Image: Into the depths of the electromagnetic spectrum

11 hours ago

It can be difficult in our everyday lives to appreciate the extraordinary range of wavelengths in the electromagnetic spectrum. Electromagnetic radiation—from radio waves to visible light to x-rays—travels ...

User comments : 0

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.