Why do you think your paper is highly cited?

Initiated by a discovery in 2004 of conductivity at the interface between non-conducting oxides (Nature 427: 423, 2004) a whole new research field has opened up in which oxide materials properties at interfaces can be completely different from bulk properties. It was also named one of Science magazine's top 10 breakthroughs of the year in 2007 (Science 318: 1844, 2007). Superconductivity between non-superconducting oxides has, for example, been found, and now we have reported on striking magnetic effects at the interface between oxides that are not magnetic by themselves.

 Would you summarize the significance of your paper in layman's terms?

Complex oxide materials form a materials class with many intriguing electronic properties, such as high-temperature superconductivity, giant magnetoresistance, and ferro-electricity. Many of these properties are exploited nowadays in electronic applications. The electronic properties of matter can usually be tuned by an electric field (e.g., the field-effect transistor) or by impurity doping (e.g., dilute magnetic semiconductors). The richness of these electronic phases and transitions between phases is now enhanced by realizing that interface effects can lead to electronic reconstruction. The interface between two oxides is found to be a source of doping, or even a source of novel electronic phases.

 How did you become involved in this research, and were there any problems along the way?

The University of Twente has a long tradition in oxide materials science, from fundamental and applied research in the field of high-temperature superconductivity to the development of pulsed-laser deposition of oxide films. In order to study interface effects in oxides, atomic control is necessary over the thin film growth, which is reached in our lab by in-situ characterization tools such as in-situ reflective high-energy electron diffraction (RHEED) and x-ray photoelectron spectroscopy. The know-how of the people and the state-of-the-art equipment enables the type of research described in our paper to take place.

 Where do you see your research leading in the future?

Currently we are working on understanding the observed magnetic scattering properties on a microscopic level. In a collaboration with the High Magnetic Field Laboratory (HFML) in Nijmegen, new experiments have already been performed, that give even more striking results, such as surprising oscillations in the magnetoresistance of our samples.

 Do you foresee any social or political implications for your research?

The general context of oxide materials research is in finding materials which are suitable for electronic, magnetic, or energy applications. Oxides might be suitable to be combined with standard semiconductor technology to go "beyond Moore's law"—which states that the number of transistors in a microchip doubles every two years—in the future. These novel interface effects will open up new possibilities in this respect.

Dr. Alexander Brinkman
Low Temperature Division
MESA+ Institute of Nanotechnology
Faculty of Science and Technology
University of Twente
Enschede, The Netherlands
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Keywords: MOTT-INSULATOR; RESISTANCE, MOORE'S LAW.