Our work is at the intersection of two rapidly evolving fields—the
science of graphene and also that of magnetism in carbon-based materials.
Five years after the first isolation of graphene, this material has become
a major research focal point in the field of physics.
And now graphene has also penetrated into the fields of chemistry,
materials science, and the engineering disciplines. Magnetism in
carbon-based materials and nanostructures is another rapidly evolving field
of research with strong implications for spin-based information technology.
These are the two main vectors which have stimulated attention toward our
work.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
In our theoretical work, we proposed a novel mechanism of magnetic ordering
in graphene induced by point defects. The work was motivated by the
experimental observations of ferromagnetism in proton-irradiated graphite.
Would you summarize the significance of your paper
in layman's terms?
Magnetic materials constitute an essential part of modern technology. All
magnetic materials used in current technology are based on the elements
belonging to either the d- or the f-block of the periodic table. For
instance, Fe, Co, and Ni (d-elements) are ferromagnetic at room
temperature.
"Our work may potentially lead to
novel materials and devices to be used in
this field of technology"
However, magnetic ordering at sufficiently high temperatures is not common
for the lighter p-block elements such as carbon, despite the fact that this
element is able to form an extraordinary number of different molecular
structures.
Magnetic materials based on carbon are nevertheless considered to be very
promising for technological applications as they may possess a number of
attractive properties such as low density, low production costs,
biocompatibility, etc. The long-awaited breakthrough in the field happened
in 2003 when ferromagnetism with Curie temperature well above room
temperature was observed in proton-irradiated graphite. This experimental
finding has quickly attracted considerable attention from the scientific
community.
Our theoretical work explains the observed magnetic ordering in terms of
the spin-polarization of the flat impurity band. This band is formed by the
quasi-localized (QL) non-binding states induced by point defects formed
upon irradiation.
These QL states are a unique feature of graphene—two-dimensional
layers which form graphite upon stacking—and had first been observed
in STM images of graphite some 20 years ago.
Proton-irradiated graphite is not considered of use for any technological
applications. Nevertheless, understanding the origin of magnetism in this
material will play an important part in the development of more practical
magnetic materials and nanostructures which are based on carbon.
How did you become involved in this research and
were any particular problems encountered along the way?
The story behind this project is a bit unusual. In 2007, I was a chemistry
graduate student at the Swiss Federal Institute of Technology in Lausanne,
Switzerland (Ecole Polytechnique Fédérale de Lausanne, EPFL).
My Ph.D. project, which was performed under the supervision of
Professor Lothar Helm, my coauthor on the
highlighted paper, was related to the theoretical investigation of
magnetism in bioinorganic systems.
However, the emerging field of graphene had attracted my attention and so I
decided to investigate. Initially, it was just a curiosity-driven project,
but it had a great influence on my academic interests which then shifted
from chemistry towards physics, materials science, and information
technology.
Where do you see your research leading in the
future?
Currently, as a postdoctoral associate at the University of California,
Berkeley, I continue my theoretical research in the field of graphene.
However, my current interests go far beyond the problem of magnetism in
graphene nanostructures. There are strong indications that graphene will
become one of the core materials in future technology and I believe that
it's worthwhile to continue working within this field.
Do you foresee any social or political implications
for your research?
No doubt, information technology plays a very important role in
today’s society. Our work may potentially lead to novel materials and
devices to be used in this field of technology.
Oleg Yazyev, Ph.D.
Postdoctoral Researcher
Department of Physics, University of California, Berkeley
and Materials Sciences Division, Lawrence Berkeley National
Laboratory
University of California at Berkeley
Berkeley, CA, USA Web