 ccording
to a recent analysis of the ISI
Essential
Science Indicators
Web product, the University at Buffalo had the highest percent
increase in total citations in the field of Physics. The
university’s record in this field includes 930 papers cited
a total of 8,065 times to date. Within the institution itself,
Physics is ranked fourth among the 16 fields of the database
in which the University at Buffalo publishes. In the essay
below, Professor and Department Chair Dr. Francis Gasparini
talks about the university’s citation record in Physics, and
another Professor in the department, Dr. Athos Petrou, talks
about his highly cited work that has contributed to the
department’s citation record.
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The University at Buffalo, or UB as
it is commonly known, is the most comprehensive graduate center within
the State University of New York system. Research in physics and
publication in physics journals at UB is centered in the Department of
Physics, but research is also done at other departments such as
Chemistry, Electrical Engineering, and Chemical Engineering. In some
cases the cited work involves collaborative work with members of the
Physics Department. In other cases,  it
is done by faculty members who have a joint or adjunct appointment
with the Department. The total number of citations over the last 10
years involves all of these activities. We are pleased that this total
research enterprise has shown such a large increase in the percent of
citations over the last two months. The research in UB Physics
publications covers a broad spectrum of subfields, including condensed
matter theory and experiments, theoretical and experimental high
energy physics, relativistic quantum mechanics of few body systems,
cosmology, biophysics, photonics, granular media, atmospheric physics,
and medical physics. The Department is particularly strong in the
condensed matter area both in theory and experiments, as well as in
high energy theory. The citations reflect, not surprisingly, the work
of the most established members of the Department. Since 1999 the
Department has added nine new faculty members and is currently
searching for three new positions. This will enhance and maintain our
future scholarly output. Further details about the Department can be
found on the Web.
Among the top four papers most cited in the last 10 years there are
two relatively recent papers on light-emitting diodes (LEDs), and spin
injection from the group of Dr. Athos Petrou. He has been a member of
the Department since 1985 working in the area of semiconductor
spectroscopy in the visible and near infrared. His comments on these
papers follow.
During the last five years a new field known as "spintronics"
has emerged. The goal in this field is to introduce the spin variable
in the operation of semiconductor electronic devices. Up until now the
operation of all electronic devices has been based solely on electric
charge. The introduction of spin is expected to increase the speed of
these new types of devices. Several technical problems have to be
addressed if spintronics is to become an effective technology. These
are:
- Generation of spin polarized carriers.
- Transport of these carriers within a device without significant
loss of spin orientation.
- Detection of the degree of spin polarization of the injected
carriers.
- Manipulation of the spins to perform a function.
Below we describe efforts to address issues 1 and 3. The work
involves the generation of spin polarized electrons and the
measurement of the degree of spin polarization via the emitted light
in specially designed devices known as "spin LEDs."
The spin injection studies involve a variety of spin injection
materials such as ZnMnSe, Fe, and CdCrSe. These have the property of
being able to inject electrons with a preferred spin state: spin -1/2
for ZnMnSe, and Fe, spin +1/2 for CdCrSe. Ordinary materials provide a
50/50 mix of the two spin states so that the net injected spin is
zero. The spin injection efficiency is determined by examining the
degree of circular polarization in the light emitted by a diode which
is fabricated in close proximity to the spin injection contact. The
injector-diode complex is known as a "spin LED." The
measurement of the polarized light can easily resolve spin
polarizations of less than 1%.
Recent developments have extended the earlier work to devices which
contain very small structures known as quantum dots. With these, spin
injection can be detected at room temperature.
In another development, there has been successful fabrication of
specially designed "permanent" Fe-based spin LEDs which
require a very small magnetic field to operate. When this external
magnetic field is removed, the spin LED "remembers" its
orientation state because the Fe spin injector has become a permanent
magnet. This type of spin LED continues to inject spin polarized
electrons without the need of an external magnetic field.
Francis Gasparini, Ph.D. and Athos Petrou, Ph.D.
Department of Physics
University at Buffalo
Buffalo, NY, USA
| University
at Buffalo's
most-cited paper in physics with 640 cites to date: |
|
ZF Ren
et al., "SYNTHESIS OF LARGE ARRAYS OF WELL-ALIGNED CARBON NANOTUBES ON GLASS,"
(Science 282: (5391) 1105-1107 NOV 6 1998). |
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Source:
ISI
Essential Science Indicators |
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cites
