Alexander Brinkman talks with
ScienceWatch.com and answers a few questions about
this month's New Hot Paper in the field of Materials
Article Title: Magnetic effects at the interface
between non-magnetic oxides
A;Huijben, M;Van Zalk, M;Huijben, J;Zeitler, U;Maan,
JC;Van der Wiel, G;Rijnders, G;Blank, DHA;Hilgenkamp,
Journal: NAT MATER
Year: JUL 2007
* Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720
* Univ Twente, MESA Inst Nanotechnol, NL-7500 AE Enschede,
(addresses have been truncated)
Why do you think your paper is highly
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?
"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
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
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 Web