Research Experiences for Undergraduates
Research Projects
The following projects will be offered for Summer 2008. More projects may be added to the list over the next few days.
You can browse through all the project descriptions, or use the links below
to jump to a project or group of projects that interests you.
You can also view research reports completed by participants in
1999,
2000,
2001,
2002,
2003,
2004,
2006,
and
2007.
For more information, please contact
the Program Director, Kevin Ingersent.
Experimental Condensed Matter/Materials Physics
Experimental Astrophysics
Experimental High-Energy Physics
 | Simulation and data analysis for the CMS proton collider experiment |
| | Neutrino physics simulation and data analysis |
Computer Modeling and Simulation
| | Modeling colossal magnetoresistance as a random resistor network |
| | Heavy-fermion quantum phase transitions |
Condensed matter/materials physics is a very broad area encompassing several research groups in the Physics Department, including biophysics, condensed matter experiment and theory, and low-temperature physics, as well as researchers in Materials sceince and Engineering. The research activities vary enormously in subject and aim; some involve fundamental investigations of novel materials or new phenomena, often at the extremes of spatial, temporal, or energy resolution; other studies are more applied in character. Much of the research is carried out in collaboration with colleagues in chemistry, engineering, and various biomedical fields.
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Effect of strain on the multiferroic properties of BiMnO3 (Prof. Amlan Biswas)
In crystalline solids, the atoms and ions arrange themselves in a periodic
array known as the crystal structure. The crystal structure plays a crucial
role in determining the myriad properties of materials. In our research group,
we are especially interested in materials that exhibit ferromagnetism and
ferroelectricity (materials which behave like charged objects). Our goal is to
fabricate materials that are both ferromagnetic and ferroelectric at the same
time. Such materials are known as multiferroics and are rare because of certain
mutually exclusive requirements on the crystal structure. Compounds from the
perovskite family of materials sometimes circumvent these mutually exclusive
requirements due to their unique crystal structures. Recently, we have
fabricated thin films of one such material, bismuth manganese oxide
(BiMnO3).
The REU student will be trained to grow thin films of BiMnO3 using
pulsed laser ablation. The student will then measure the magnetization of the
thin films to check if they are ferromagnetic. Once the ferromagnetism is
confirmed, we will measure the influence of strain on the ferroelectric
polarization of the thin films. These experiments will lead to a better
understanding of the mechanism for multiferroism in materials and give rise to
techniques for the fabrication of new multiferroic materials.
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Fabrication and characterization of novel materials in restricted geometries (Prof. Art Hebard)
The Hebard group is investigating the electrical properties of novel
materials in restricted geometries. Understanding this area of nanoscience
is a prerequisite for incorporating nanostructured building blocks into
future technologies. Projects under consideration include the search for a
ferroelectric response in organic single-molecule magnets and the use of novel
templating procedures to form one-dimensional wires of metals and complex metal
oxides spanning two closely spaced electrodes. Measurements will be made at
temperatures down to 4 K and in magnetic fields as high as 7 teslas. Some of
these measurements will be made in situ during the growth of the structure so
that a real time evolution of the electrical properties of the structure can
be ascertained.
The REU student will use thin-film deposition techniques (thermal sublimation,
reactive ion beam deposition, and rf/dc sputtering) to fabricate one- and
two-dimensional structures with a variety of materials. The student will
become familiar with lithographic patterning techniques and post-deposition
processing in a clean-room facility using both wet and dry etching. The
student will then measure the electrical transport and charging response of
the completed structures with instrumentation including current sources,
voltmeters, impedance bridges, electrometers, frequency-dependent capacitance
bridges, and ferroelectric testers. Data analysis and interpretation will be
emphasized.
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Quantum effects in molecular nanomagnets (Prof. Stephen Hill)
This is an interdisciplinary research effort aimed at exploring and
understanding quantum effects in chemically synthesized magnetic
nanostructures. The miniaturization of magnetic devices to the nanoscale
is critical to advances in magnetic information processing, which is a huge
industry in the United States. Conventional "top-down" techniques used to
fabricate magnetic nanostructures have serious limitations. For this reason,
there is growing interest in chemical syntheses that provide a "bottom-up" or
molecule-based approach to the assembly of magnetic nanostructures–often
with atomic-scale control.
This project focuses on quantum magnetization dynamics. Work in the Hill
lab involves the use of electron paramagnetic resonance (EPR) spectroscopy
to study crystals containing molecular nanomagnets. This work combines many
exciting experimental methods: low-temperatures; high magnetic fields; and
microwave electronics spanning the range from 10 to ~500 GHz. We obtain
crystals of molecular nanomagnets from chemistry research groups both
at the University of Florida and at other institutions in the US, Europe and
Asia. We also collaborate with other physicists in the US and Europe in order
to combine EPR spectroscopy with other advanced characterization techniques.
We use these spectroscopies (a) to characterize the energy spectrum of a given
molecular nanomagnet, and (b) to study non-equilibrium effects, i.e., dynamics.
The coupling between a magnet and its surroundings strongly influences its
dynamics, leading, e.g., to energy dissipation or magnetic friction. For
magnetic nanostructures, environmental coupling also leads to loss of quantum
information, known as decoherence. An important aim of this project is to
understand the mechanisms of energy dissipation and decoherence in nanomagnets,
and to develop synthetic strategies to mitigate decoherence.
This project will offer the REU student excellent cutting-edge applications of
many topics covered in undergraduate courses. Indeed, undergraduates have made
important contributions to this effort in the past. In addition to experimental
work, opportunities exist for the REU student to develop computer programs
(using MATLAB, Mathematica, C++, etc.) for simulating experimental data.
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Quantum turbulence: Decay in a frictionless fluid (Prof. Gary Ihas)
An experiment is being constructed in collaboration with the University
of Lancaster (England) to study the decay of turbulence in superfluid
4He at 20 mK, where there is no viscosity and therefore no
classical dissipation. This summer we will be taking calorimetry
measurements producing turbulence using a grid pulled through the helium
by a superconducting linear motor.
The REU student will learn to operate a dilution refrigerator and a
liquid-helium purifier. He or she will use LabView to take measurements
of the helium sample temperature after pulling the grid using
thermistors of 300-micron diameter immersed in the helium at 20 mK. It
is expected that a paper will be presented by the group on this work at
QFS2006 in Kyoto in early August.
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Properties of novel low-dimensional magnetic materials (Prof. Mark Meisel)
The Meisel group is studying the
electromagnetic, thermodynamic, and magneto-optical properties of a
variety of novel low-dimensional systems
down to millikelvin temperatures in order to understand
the underlying quantum-mechanical phenomena.
Recently the group has discovered
that the static magnetization of
some of the two-dimensional Prussian blue analog materials
can be changed by irradiation with visible light.
Such optical control of magnetization has many potential applications.
The REU student will measure the magnetic properties of some
of these new materials using a SQUID magnetometer.
A home-made optical probe
will allow the student to optically excite the material
and perform measurements from room temperature
down to 2 K and in magnetic fields up to 7 T.
The effect of optical excitations on the anisotropy
of the magnetic response will also be explored.
The student will learn
how to use Labview, lock-in amplifiers, and temperature controllers,
and how to perform quantitative data analysis.
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Hydrogen storage materials (Prof. Neil Sullivan)
At present there is much interest in the possibility of an environmentally
friendly hydrogen economy in which power is generated by reacting hydrogen
and oxygen. One of the key technical steps towards realizing the hydrogen
economy is developing safe and compact methods for storing H2.
The Sullivan group is studying the properties of molecular hydrogen in
nanoporous materials, ranging from natural zeolites to tailored metal
organic frameworks. The goal of the studies is to determine how to optimize
(1) the volume of hydrogen that can be stored per unit mass of storage material
and (2) the release of that hydrogen in and end device.
The REU student will design a small but simple device for measuring adsorption
of hydrogen in commercially available zeolites. The student will use
a table-top variable temperature cryostat to carry out the measurements.
The results of these studies will be used to set up nuclear magnetic
resonance experiments to determine the structural arrangements and adsorption
energies of hydrogen in various storage materials.
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Heat capacity of low-dimensional antiferromagnets at low temperatures (Prof. Yasu Takano)
Antiferromagnets are solids in which the magnetic dipole moments
of neighboring atoms prefer to align antiparallel to each other. In some
antiferromagnets, the dipole moments form a two dimensional or one
dimensional arrays rather than three-dimensional periodic structures.
Low-temperature properties of such low-dimensional antiferromagnets are
poorly understood and are the subjects of many experimental and
theoretical studies at the moment.
The REU student will measure the heat capacity of novel low-dimensional
antiferromagnets at temperatures below 10 K to gain microscopic insights
into their macroscopic properties near zero temperature. The student will
become familiar with experimental techniques at low temperatures, and use
of computers in data acquisition and data analysis, as well as various
elements of modern magnetism and thermal physics. If a magnet time is
available at the National High Magnetic Field Laboratory at Tallahassee,
the student may participate in a five-day experiment at one of the
highest magnetic fields in the world.
Publications relevant to this project:
[1] H. Tsujii et al., Physica B 329-333, 1638 (2003).
[2] J.S. Helton et al., Phys. Rev. Lett. 98, 107204 (2007).
[3] H. Tsujii et al., Phys. Rev. B 76, 060406(R) (2007).
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Enhanced transmission by periodic hole arrays in metal films (Prof. David Tanner)
Periodic arrays of sub-wavelength holes exhibit surprising optical behavior.
For example, the optical transmission may peak around 75% at certain
wavelengths in silver films where small holes make up 25% of the surface area.
This is a puzzle, since diffraction is expected to reduce the transmission much
below the 20% value predicted by geometric optics.
Issues studied by the Tanner group include the dependence on hole size and
spacing of the wavelengths at which the enhanced transmission peaks occur, the
behavior of different metals and transparent conducting oxides, and
the influence on the refractive index of the media on either side of the metal
film.
In investigating one of these issues, the REU student will become skilled at
optical and infrared spectroscopy, acquire an understanding of the optics of
thin metal films, and gain experience in an area of research on the boundary of
physics and materials science.
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UF scientists are involved in a number of large-scale efforts to detect massive particles and gravitational waves generated by astrophysical events. REU projects are offered in connection with three of these experiments.
Stability of a tunable high-Finesse optical cavity for the LISA frequency stabilization system (Prof. Guido Mueller)
The Laser Interferometer Space Antenna
(LISA) is a joint NASA/European Space Agency project aiming to detect
gravitational waves from distant super-massive black holes, supernovae, and
galactic binaries.
LISA is one of the facility class missions in NASA's "Beyond Einstein" program
and is projected to be launched in 2012. LISA will
consist of three spacecraft flying in formation in a heliocentric orbit.
The distance between the spacecraft will be monitored by laser interferometers
to observe changes brought about by gravitational waves.
The LISA project requires a sophisticated stabilization system to cancel
the otherwise overwhelming laser frequency noise. The laser frequency
noise in LISA will be reduced in a two-step process. The first step is to
stabilize the frequency to an ultra-stable optical cavity formed between two
highly reflective mirrors. The residual frequency noise is then further
reduced by stabilizing the optical cavity to the distance between the LISA
spacecraft. To achieve this, one of the mirrors is mounted on a piezoelectric
crystal (PZT) that allows control over the length of the cavity through a
feedback mechanism. The goal of this project is to measure the stability of
a PZT-actuated cavity and compare this with the stability of non-actuated
cavities.
The REU student will learn how to mode match and align a laser
beam into the PZT-actuated cavity which sits inside a
thermally insulated vacuum tank. The student will then
stabilize the frequency of a laser field to the
eigenfrequeny of the optical cavity using a
modulation/demodulation technique and a feedback servo
system. The laser frequency will then be compared with
the laser frequency of a similar system that uses a
non-actuated ultra-stable cavity.
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Cryogenic system alignment for rocket-borne x-ray telescopes (Prof. Tarek Saab)
Research in the Saab group focuses on the application of
superconducting devices as particle detectors for a variety of
astrophysics measurements ranging from dark matter detection
(Cryogenic Dark Matter Search Experiment) to rocket-borne x-ray
telescopes (NASA's micro-X mission).
By operating a superconducting film in the middle of
its normal-to-superconducting transition, we are able to observe a
large resistance change as a consequence of a small change in the
sensor's temperature. This translates into an excellent energy
sensitivity for any particle which interact in such detectors.
In order for these devices to function in an x-ray telescope, the
cryogenic system that cools the device to the superconducting
point must be well aligned with the optics that focus and
image the incoming x-rays.
The REU student will take part in the design and construction of a
position alignment system that will allow the continuous, real-time
orientation of the cryogenic system with respect to the
telescope optics. The student will also gain experience in the
operation, calibration, and simulation of the detector behavior.
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Development and characterization of high-power laser and optical components for advanced LIGO detectors (Prof. David Tanner)
The Laser Interferometer
Gravitational-Wave Observatory (LIGO) project is a
pioneering effort to design and construct a gravitational-wave observatory
which will open a new observational window on the universe. LIGO consists
of two laboratories located far apart within the United States. Each of
these facilities incorporates L-shaped vacuum systems with arms of 4 km
length. The vacuum systems house laser interferometer detectors sensitive
to gravitational waves from astrophysical sources. Correlation of data from
interferometers at the two sites will allow identification of gravitational
waves and will extract a significant portion of the information they carry.
The ultimate goal of LIGO is to test relativistic gravitation and to open
the field of gravitational wave astrophysics.
The UF LIGO group is participating in the operation of the initial LIGO
detector, the analysis of LIGO data, and planning and development work
for future upgrades.
LIGO has begun the search for gravitational waves and will carry out an
observation program lasting 3 to 4 years. Upon its completion, the LIGO
interferometers will be upgraded to improve their sensitivity by a factor
of 10 to 20. One of the key technology improvements will be to increase the
power of the laser from 8 W to 180 W. The UF LIGO Group is responsible for
developing high-laser-power optical components and characterizing their
performance for this Advanced LIGO Detector.
The REU student will develop instrumentation and methods for characterizing
thermal distortions in optical materials, investigate methods for
mitigating these distortions, and will model the experimental results using
Gaussian modal theory. The student will learn safely to operate high-power
Nd:YAG lasers, to set up and align complex optical experiments, and to
write data acquisition software and collect data using Labview-based
programs. In addition, he or she will develop a quantitative understanding
of Gaussian optics. Although initially working closely with senior
laboratory members, the student will be the primary investigator on these
experiments.
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Simulation and data analysis for the CMS proton collider experiment (Prof. Andrey Korytov)
Research at the high-energy frontier of particle physics is a quest to
understand nature at its most fundamental level. In particular, current
experiments are examining the origin of mass, searching for new
symmetries in nature, and looking for hints of a grand unified theory
able to relate all four fundamental forces in nature.
The Compact Muon Solenoid (CMS)
experiment is a major high-energy physics experiment under
construction at the CERN Laboratory in Geneva, Switzerland.
It will study proton collisions at an unprecedented center-of-mass
energy of 14 trillion electron-volts at the Large Hadron
Collider (LHC), and will allow physicists to determine the nature of the
symmetry breaking between the electromagnetic and weak nuclear forces and
determine the origin of particle mass. It might also offer a window
into a supersymmetric world (one with particles with opposite spin
statistics from the known ones) or a world with extra dimensions. The
LHC will be completed and begin taking data this year.
The CMS Detector is now being commissioned and tested using cosmic-ray data.
Cosmic ray muons offer a perfect oportunity to study the performance of the
CMS muon system and to optimize muon reconstruction algorithms, both of which
are actively being pursued by the UF high-energy experimental group.
In addition, the UF group is leading preparations
for a data analysis aiming at discovering the Higgs boson in its decay channel
H --> Z + Z --> 4 muons. The REU student can work in either of these areas.
A good working knowledge of C++ (preferred), C, or Fortran is required.
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Neutrino Physics Simulation and Data Analysis (Prof. Heather Ray)
Neutrinos are fascinating little creatures. While the past ~10 years
have seen enormous advances in our knowledge of what neutrinos are and
how they interact, there are still large gaps in our understanding.
The Experimental Neutrino Physics group at UF studies neutrino
oscillations, the phenomenon of neutrinos changing from one flavor
to another. The UF Neutrino group is currently involved in two
experiments. MiniBooNE is searching for neutrino oscillations using
neutrinos and anti-neutrinos. MiniBooNE has been collecting data for
several years, and is expected to continue running through
September 2009. The Osc-SNS is a experiment designed to search
for sterile neutrinos. Osc-SNS is in the pre-proposal stage, with a
full proposal to be submitted in Fall 2008/Spring 2009.
There are two projects suited for a REU student with a
thorough working knowledge of C or C++.
The first project involves working on the simulation for the
Osc-SNS neutrino experiment. The student will gain
experience with Geant 4, a common simulation program used
in a wide variety of scientific applications (particle physics,
astronomy, dark matter, medicine). Geant 4 offers the user a
choice of several particle interaction rate
(cross sections) predictions in each energy region (low, medium, high).
These different physics models need to be verified against
existing experimental data. The student will determine which model,
if any, should be used for the Osc-SNS experiment. These models are
not expected to match experimental data perfectly. The student will
modify the chosen model to produce a physics model best suited to the
Osc-SNS. This work is highly important,
and will be included in the Osc-SNS proposal for funding.
The second project is a comparison of data and Monte Carlo prediction
for the MiniBooNE experiment, in the anti-neutrino data set. The
student will examine low-energy events which pass our
oscillation selection criteria. The rate and shape of events
in data will be compared to the theoretical prediction, using a
variety of statistical tests. The student will gain experience
with Chi-Square and K-S tests. This specific details of this
project are fluid; they depend upon how well the Monte Carlo matches
the observed distribution in these events. Should we observe an excess
of events in anti-neutrinos (as was seen in the neutrino data set)
one set of tests will need to be performed. If there is no excess,
a second set of tests will be devised to compare the neutrino and
anti-neutrino events.
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Modeling colossal magnetoresistance as a random resistor network (Prof. Selman Hershfield)
The Colossal Magnetoresistance (CMR) materials exhibit a transition
from a high resistance state to a low resistance metallic state in
an applied field magnetic field. One model of this transition is
that the magnetic field causes the metallic state to be the lower
energy state. As the field is increased small metallic regions
increase in size until they coalesce into a conducting path which
traverses the entire sample.
In this project, CMR will be modeled as a random resistor
network, where the resistors represent the different nonmetallic
regions separating metallic islands. Some modest programming
experience is desirable, particularly with matlab. Only introductory
physics is needed to understand the random resistor network model.
The results of these simulations will be used to interpret recent
experimental data from Prof. Biswas' group.
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Heavy-fermion quantum phase transitions (Prof. Kevin Ingersent)
Heavy-fermion systems are compounds or alloys containing unpaired 4f or
5f electrons, in which the strong electron-electron interactions manifest
themselves in a greatly increased conduction-electron effective mass
m*.
Of particular current interest are "non-Fermi liquids" in which
m* tends to infinity
as the temperature approaches absolute zero, apparently due to
proximity to a quantum phase transition (QPT) between magnetic and nonmagnetic
ground states of the system.
The REU student will study a simplified model for heavy-fermion QPTs that
focuses on a single localized f spin coupled to an effective medium
representing the rest of the metal.
Using pre-existing computer programs the student will design, code, and test
driver routines for identifying the location of the QPT. The student will then
use the same programs to compute the physical properties near the QPT, deduce
the values of critical exponents, and explore the possibility of collapsing the
data using scaling functions. The student will acquire a knowledge of basic
solid-state physics, critical phenomena, and key concepts in strongly
correlated systems.
Prior experience with Unix/Linus and programing (e.g., Fortran or C) will
be helpful.
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This material is based upon work supported by the National Science Foundation under Grants DMR-9820518 and DMR-0139579. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. |