Article Title: Visualizing pair formation on the
atomic scale in the high-T-c superconductor
Authors: Gomes, KK;Pasupathy, AN;Pushp, A;Ono, S;Ando,
Year: MAY 31 2007
* Princeton Univ, Joseph Henry Labs, Dept Phys, Princeton,
NJ 08544 USA.
(addresses have been truncated)
Why do you think your paper is highly
This paper describes the use of newly developed experimental techniques to
watch superconductivity—the phenomena of flow of electricity without
resistance—develop on the atomic scale in a superconducting material.
The material system we studied is a ceramic superconductor, the mechanism
for which has been the subject of intense debate for the last 20 years
within the physics community. Perhaps the combination of a newly developed
technique together with unraveling new microscopic information on the
enigmatic ceramic superconductors has contributed to the paper's high
Does it describe a new discovery, methodology, or
synthesis of knowledge?
The paper described both a new methodology for studying superconductivity
and an important new finding. Specifically, the paper shows how the
superconducting state forms, starting with small nanoscale patches with
superconducting-like properties in the material, at temperatures far higher
than had been anticipated before.
It has often been assumed that the transition temperature where samples
exhibit zero resistance is when superconducting behavior first occurs. This
paper shows that, at temperatures well above the bulk transition
temperature, if one looks carefully using specialized tools and techniques,
we can identify nanoscale puddles of superconducting behavior up to very
high temperatures. There had been hints of superconducting "fluctuations"
above the transition temperature but "seeing" them with our technique has
been a significant advance and an example of more direct evidence for this
Would you summarize the significance of your paper in
Superconductivity, the ability to carry electricity without resistance, can
have a significant impact on the future distribution of electrical energy.
It can play a role both in making power transmission lines more efficient,
yet also provide the technology which can make them more immune to the
failure that causes power outages.
"...the paper shows how the
superconducting state forms, starting with
small nanoscale patches with
superconducting-like properties in the
material, at temperatures far higher than had
been anticipated before. "
However, any realistic application requires the development of
superconductors with higher transition temperatures and better
current-carrying properties than are available today. Understanding the
mechanism of superconductivity in the highest temperature superconductors
is hence significant in achieving advances in this area. Our finding that
the nanoscale region of a ceramic material can exhibit superconducting
behavior at temperatures higher than anticipated can perhaps be used to
develop new materials with higher superconducting transition temperatures.
How did you become involved in this research, and were
there any problems along the way?
I have been fascinated by superconductors for the past 20 years, and I have
been very interested in the last 10 years in developing the tools to study
superconductors on the atomic scale. This research was made possible with
the development of a new generation of scanning tunneling microscope (STM),
which can be used to study evolution of electronic phenomena while varying
temperature. The most significant challenge we had to overcome was to
develop an STM that can track the same atom on the sample, while the
temperature was being varied and the sample was undergoing thermal
expansion and contraction.
Where do you see your research leading in the
Our ability to correlate atomic scale properties together with
superconducting properties will be quite useful in understanding the
mechanism of pairing in high-temperature superconductors as well as in the
design of new superconductors to be discovered at some point in the future.
In addition, the experimental tool we have developed can be used to examine
a variety of other phase transition phenomena in materials—such as
magnetic transition—with atomic scale resolution. We are currently
busy working on these two fronts.
Ali Yazdani, Professor
Department of Physics
Princeton, NJ, USA