Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Scientists open door to better solar cells, superconductors and hard-drives: Research enhances understanding of materials interfaces

Left: If the lanthanum aluminate layer (blue) is less than three unit cells, the electrons redistribute in sub-layers. Right: If the layer has four unit cells or more, some electrons migrate to the interface. Credit: Michael Rübhausen, University of Hamburg
Left: If the lanthanum aluminate layer (blue) is less than three unit cells, the electrons redistribute in sub-layers. Right: If the layer has four unit cells or more, some electrons migrate to the interface.

Credit: Michael Rübhausen, University of Hamburg

Abstract:
Using DESY's bright research light sources, scientists have opened a new door to better solar cells, novel superconductors and smaller hard-drives. The research reported in the scientific journal Nature Communications this week enhances the understanding of the interface of two materials, where completely new properties can arise. With their work, the team of Prof. Andrivo Rusydi from the National University of Singapore and Prof. Michael Rübhausen from the Hamburg Center for Free-Electron Laser Science (CFEL) have solved a long standing mystery in the physics of condensed matter. CFEL is a cooperation of DESY, the University of Hamburg and the Max Planck Society.

Scientists open door to better solar cells, superconductors and hard-drives: Research enhances understanding of materials interfaces

Hamburg, Germany | Posted on April 14th, 2014

"Interfaces are a hot topic in materials research," says Rusydi. "If two dissimilar materials are put together, completely new properties may be generated. For instance, two insulators and non-magnetic materials can become metallic and magnetic at their interface." The reason for this change of personality of the two materials is the broken symmetry at the interface, explains Rübhausen, who is a professor at the University of Hamburg. "The two materials have different characteristics and different structures. If you put them together, they have to make a deal and rearrange, and this leads to new properties."

Making use of these phenomena can lead to smaller hard-drives, for example. "Conventional hard-drives are currently controlled by bulk physical properties of the material, for miniaturization we would like to control their physical properties by the interface structure," says Rusydi. "The problem is that we do not yet fully understand what is happening at the interface." As an example, the team investigated the interface of strontium titanate (SrTiO3) and lanthanum aluminate (LaAlO3), two insulators that become conductors at their interface. "However, based on Maxwell's theory, a tenfold higher conductivity should be observed. So, 90 per cent of the charge carriers, the electrons, have gone missing. That was a complete mystery to us," says Rusydi.

In search of the "missing electrons" the scientists used DESY's bright synchrotron radiation source DORIS III to floodlight the interface of the two materials in a wider ultraviolet energy range than any investigation had used before. "All the electrons in the material are like small antenna that respond to electromagnetic radiation at different wavelengths, depending on their energy state," explains Rusydi. The absorption of synchrotron radiation at specific wavelengths reveals the energy state of the corresponding electrons and thus their hiding place in the crystal lattice.

The investigation showed that only a fraction of the expected electrons actually migrate to the interface to form a conducting layer. Most of the electrons redistribute in sub-layers within the lanthanum aluminate, where they were hidden from techniques used in previous investigations. Also, the scientists observed that the transfer of electrons from the crystal to the interface depends on the number of so-called unit cells of lanthanum aluminate in the crystal lattice. A unit cell is the smallest unit of a crystal, this means a crystal can be described as many identical unit cells. If the lanthanum aluminate layer is less than three unit cells thick, all electrons redistribute within the lanthanum aluminate sub-layers and no electrons transfer to the interface anymore which then remains an insulator.

This explains, why more than just one layer is necessary to fully unfold the interface properties. "If only a part of the electrons migrate to the interface, you need a bigger volume to compensate for the symmetry breaking," explains Rusydi. With their work, the scientists can now better understand the behaviour of this and of other interfaces. "In principle, our experimental technique can be used to study any interface," says Rübhausen. "We have only just begun to investigate the basic interface characteristics with it." Although further investigations will have to wait until the Superlumi experimental station that has been used for this work has been moved from the now retired light source DORIS III to DESY's current machine PETRA III. "There currently is no facility in the world that can measure this," Rübhausen says.

The scientists expect that with a better understanding of interfaces, their properties can be more easily tweaked to desired characteristics. "If we learn to control the interface, we can design completely new properties and control them," says Rübhausen.

####

About Deutsches Elektronen-Synchrotron DESY
Deutsches Elektronen-Synchrotron DESY is the leading German accelerator centre and one of the leading in the world. DESY is a member of the Helmholtz Association and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90 percent) and the German federal states of Hamburg and Brandenburg (10 percent). At its locations in Hamburg and Zeuthen near Berlin, DESY develops, builds and operates large particle accelerators, and uses them to investigate the structure of matter. DESY's combination of photon science and particle physics is unique in Europe.

For more information, please click here

Contacts:
Dr. Thomas Zoufal

49-408-998-1666

Copyright © Deutsches Elektronen-Synchrotron DESY

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Reference

Related News Press

News and information

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Chip Technology

Instant-start computers possible with new breakthrough December 19th, 2014

Switching to spintronics: Berkeley Lab reports on electric field switching of ferromagnetism at room temp December 17th, 2014

Pb islands in a sea of graphene magnetise the material of the future December 16th, 2014

Stanford team combines logic, memory to build a 'high-rise' chip: Today circuit cards are laid out like single-story towns; Futuristic architecture builds layers of logic and memory into skyscraper chips that would be smaller, faster, cheaper -- and taller December 15th, 2014

Memory Technology

Instant-start computers possible with new breakthrough December 19th, 2014

Switching to spintronics: Berkeley Lab reports on electric field switching of ferromagnetism at room temp December 17th, 2014

Stanford team combines logic, memory to build a 'high-rise' chip: Today circuit cards are laid out like single-story towns; Futuristic architecture builds layers of logic and memory into skyscraper chips that would be smaller, faster, cheaper -- and taller December 15th, 2014

Graphene layer reads optical information from nanodiamonds electronically: Possible read head for quantum computers December 1st, 2014

Announcements

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Energy

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

How does enzymatic pretreatment affect the nanostructure and reaction space of lignocellulosic biomass? December 18th, 2014

Iranian Scientists Use Nanotechnology to Increase Power, Energy of Supercapacitors December 18th, 2014

Lifeboat Foundation gives 2014 Guardian Award to Elon Musk December 16th, 2014

Solar/Photovoltaic

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Lifeboat Foundation gives 2014 Guardian Award to Elon Musk December 16th, 2014

Stacking two-dimensional materials may lower cost of semiconductor devices December 11th, 2014

New Technique Could Harvest More of the Sun's Energy December 9th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE