Mystery At Material Interface Unveiled

Researchers from Singapore and Germany have found a new way to study the curious properties observed at the interface of materials.

AsianScientist (Apr. 21, 2014) – An international team led by researchers at the National University of Singapore (NUS) has developed a technique to study the interface between materials, shedding light on the curious properties that arise when two materials are put together.

Studying material interfaces is part of a research area known as condensed matter physics. When matter is condensed, mutual interactions between particles alters physical behavior, giving rise to exotic properties. A better understanding of how materials interface allows scientists to tweak material properties to possibly develop better solar cells, superconductors and smaller hard drives.

“If you put two materials together, you can create completely new properties. For instance, two non-conducting, non-magnetic insulators can become conducting and in some cases ferromagnetic and superconducting at their interface,” explains NUS Assistant Professor Andrivo Rusydi, who led the research.

The team investigated the electrical conductivity of strontium titanate and lanthanum aluminate, two insulators that become conductors at their interface. They observed that conductivity was ten-fold less than what was predicted theoretically, meaning that 90 percent of the expected electrons were missing.

To find the missing electrons, the team used high-energy reflectivity and spectroscopic ellipsometry experiments which flooded the interface with a wide range of energy. This revealed electrons that were bound within the molecular lattice, which prevented them from moving and explained the observed low conductivity.

The team’s new approach and insights, which culminated in a recent publication with Nature Communications, will be used for further investigations on the basic interface characteristics among materials.

The article can be found at: Asmara et al. (2014) Mechanisms of charge transfer and redistribution in LaAlO3/SrTiO3 revealed by high-energy optical conductivity.

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Source: National University of Singapore; Photo: Börkur Sigurbjörnsson/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Alan Aw is a maths enthusiast who likes sharing the fun and beauty of science with others. Besides reading, he enjoys running, badminton, and listening to (and occasionally playing) Bach or Zez Confrey.

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