Using DESY’s 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 Communications1 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 Centre for Free-Electron Laser Science, have solved a long standing mystery in the condensed matter physics.
“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 control of physical properties by the interface structure is not achieved yet. Indeed the process at the interface is not well understood. Using DESY’s bright synchrotron radiation source DORIS III, the researchers showed that only a few electrons actually migrate to the interface to form a conducting layer and the transfer of electrons from the crystal to the interface depends on the number of unit cells in the crystal lattice. “If only a part of the electrons migrate to the interface, you need a bigger volume to compensate for the symmetry breaking,” explains Rusydi.
“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, which has been used for this work moves 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 tweaked to desired characteristics more easily. “If we learn to control the interface, we can design completely new properties and control them,” says Rübhausen.
- “Mechanisms of charge transfer and redistribution in LaAlO3/SrTiO3 revealed by high-energy optical conductivity”; T.C. Asmara et al.; Nature Communications (2014) [↩]