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Physics

Research Projects

The REU research program was designed by our faculty after taking into account the limited research experience of REU students. Although 15 research projects are described below, one from each of the participating faculty, only 10 will be active within the program in a current year: one per REU student. This flexibility will be helpful in providing the prospective REU students a possibility to choose the research project that they prefer.

1. Biomedical nanoscience and nanotechnology (D. Haynie: Biomedical/Biophysics & Materials Physics & Optics).
The REU student will become a member of this interdisciplinary and entrepreneurial laboratory focused on design, fabrication and characterization of nanostructured, polymer-based biomaterials.  Materials of particular interest are nanocoatings for cell and tissue culture, nanocoatings for medical implant devices, and nanostructures for combating cancer.  Spectroscopic, acoustic, and microscopic methods are used for physical and chemical characterization.  Biological characterization is done by cell culture and other methods. An REU student will design, fabricate, and characterize polypeptide multilayer nanofilms with regard to key physical and biological properties.  Characterization will be used to make decisions concerning feasibility of technology translation to the private sector, and product development.  The REU student will use a pH meter, a spectrophotometer and a multi-well plate reader. They will culture mammalian cells, and quantify some aspects of cell behavior, such as proliferation.  The student will participate in all general laboratory activities, including research group meetings, preparation of manuscripts for publication, and the periodic interaction with entrepreneurs. Publication of the REU student’s work in peer/reviewed journals is considered a high priority.

2. Systematic studies of semicrystalline polymer mechanics (Hoy: Materials Physics).
Dr. Hoy's laboratory investigates the structural, mechanical, and dynamical properties of soft materials using coarse-grained simulations and analytic modeling.  One of the “grand challenges” in polymer physics is to theoretically predict the mechanical response of bulk solids from the elastic regime through catstrophic failure (i.e. fracture).  Our current ability to predict the response of semicrystalline systems (the majority of real materials) is very poor.  Planned research will improve our understanding of semicrystalline polymer mechanics through coarse-grained simulations of model systems with continuously variable crystallinity.  The REU student will be trained to use the public-domain molecular dynamics (MD) code LAMMPS (http://lammps.sandia.gov) for this purpose, and will perform related MD simulations and data analysis.  The student will be part of a team effort, but one which should produce (and offer the opportunity to coauthor) publications in high-profile peer-reviewed journals.

3. Nonlinear two-dimensional laser spectroscopy on quantum dots (D. Karaiskaj: Optics & Materials Physics).
The condensed matter/materials physics optical and laser spectroscopy laboratory is focused on applying state-of-the-art optical and laser spectroscopy techniques to study the fundamental properties of advanced materials. The REU student will apply the advanced optical and laser spectroscopy technique to study the electronic, vibrational, and light-matter interactions in quantum dots used for solar energy harvesting. Working closely with a graduate student mentor, the REU student will set up a multidimensional nonlinear optical spectrometer, and perform two-dimensional spectroscopy on a variety of nanomaterials. Using femtosecond laser pulses, the REU student will investigate the formation of dissociation of excitons, multiple exciton generation, and carrier lifetime and diffusion lengths in these advanced materials. These parameters are crucial for improving the efficiency of light harvesting devices. Single nanostructure spectroscopy will also be used by the REU student to perform photoluminescence and photoluminescence lifetime measurements on individual nanostructures. The REU student will receive extensive training in optics, nonlinear ultrafast laser spectroscopy, laser microscopy, and materials physics,   

4. Holographic tracking of swimming euglenas (M. Kim: Optics & Biomedical/Biophysics).
The Digital Holography and Microscopy Laboratory (DHML) focuses on the development of novel imaging technologies with emphasis in holographic and interferographic microscopy. Digital holography is an emerging technology that has potential applications in wide-ranging areas including cellular microscopy, metrology, manufacturing processes and testing, medical imaging and diagnostics, biometry, environmental research, and food science. An REU student will use a digital holographic microscopy apparatus to track the three-dimensional positions of swimming euglenas in real time. The effectiveness of this method will be quantified in terms of the maximum number and speed of the moving microbes that can be tracked, as well as the direction of the motion (lateral and axial). The results from this work will be used to implement an optical trap that can automatically track and capture microbes with specified characteristics, such as speed, size, or shape. During this project, the student will learn various aspects of holography, optomechanics, computer programming, biophotonics, and image processing, and will be trained extensively in advanced optical design and construction, digital image acquisition, computer programming, electronic instrumentation, and cellular and biomedical laboratory procedures. It is expected that this project will produce new results that will be publishable in a peer-reviewed journal.

5. Mechanics of Proteoglycans (G. Matthews: Biomedical/Biophysics & Materials Physics).
Proteoglycans bound to the surface of type I collagen fibrils are believed to be instrumental in the spatial distribution of these fibrils in tendon and cornea; and interactions between the proteoglycans are thought to be at least partially responsible for load support in these tissues.  Therefore, an understanding of the assembly process and mechanics of such collagenous tissues requires a detailed understanding of the mechanics of the proteoglycan constituents.  The REU student will measure the mechanical properties of individual proteoglycan molecules.  They also will measure the interaction forces at the single molecule scale.  To accomplish this goal, the student will use surface chemistry techniques to tether proteoglycans and their glycosaminoglycan sugar components to planar silicon wafer surfaces and atomic force microscopy tips.  Force spectroscopy will be performed to extract the persistence of the molecules, and to measure the interaction force between the molecules.  These experiments are central to a funded NSF GOALI proposal, allowing the student to interact with the industrial partner. 

6. Gd exchange bias as a probe of antiferromagnetic order (C. Miller: Materials Physics).
Dr. Miller’s spintronics laboratory investigates spin-dependent transport in materials and devices that are fabricated by a combination of thin film growth and lithography, and characterized via cryogenic transport measurements in high magnetic fields. This REU project will study the fundamental physics of exchange bias - an interfacial phenomenon that occurs when a ferromagnet/antiferromagnet (F/AF) heterostructure is cooled in a magnetic field below the Néel temperature (TN) of the AF. In this project, the REU student will study the thickness dependence of the spin structure in an AF (e.g, IrMn) via trilayers such as Gd/IrMn/Fe as a function of temperature. Upon cooling below TN, the AF spin order will be influenced solely by the exchange interaction at the IrMn/Fe interface.  Further cooling below the Curie temperature of Gd will allow the probing of the intrinsic AF order at the Gd-IrMn interface through the magnitude of the resulting the exchange bias field.  This REU project will employ routine film deposition and magnetometry, both of which are accessible to undergraduates after extensive but straightforward technical skills training. This is a sufficiently novel experiment that will definitely result in publications in peer-reviewed journals.

7. Intrinsic protein fluorescence as indicator of amyloid aggregation (M. Muschol: Biomedical/biophysics & Optics).
Oligomeric intermediates have received considerable attention since they have been implicated as the molecular substrate leading to the neurotoxic effects associated with Alzheimer's disease. In this project, an REU student will explore whether intrinsic tryptophan fluorescence of lysozyme, a small protein that can form amyloid fibrils, can be used to detect small populations of oligomeric intermediates during fibril growth. The REU student will be introduced to the use of spectroscopic techniques (fluorescence spectroscopy) for studying aggregation behavior and structural changes in biological macromolecules.  Extensive training will be provided to acquire the necessary technical skills in fluorescence spectroscopy, as well as for the preparation and characterization of biological samples. The REU student will be involved in an intrinsically interdisciplinary research project in which they benefit from multiple interactions with faculty in the Physics Department, in the School of Engineering, and at the Medical School.

8. Nano-scale thermoelectric enhancement for solid-state refrigeration and power conversion (G. Nolas: Materials Physics). The development of novel materials for significant advancements in energy-related technologies requires a comprehensive understanding of the material’s structure-property relationships: the effect of structural and chemical variations on the transport, optical, magnetic, and mechanical properties of materials. This project will focus on higher efficiency nanostructured thermoelectric (TE) materials where the interdependence of the electrical and thermal transport allows for greater optimization of the thermoelectric properties. Understanding the physical mechanism responsible for thermopower enhancement in these materials is the goal of this REU project. An REU student will synthesize nanocrystal Bi2Te3 and metal-semiconductor composite TE materials by solution-phase synthesis. Subsequent densification of these nanocrystals, i.e. nanocrystals densified within a macro-scale nanocomposite, will be used by the REU student to measure the transport properties. This project will promote further insight and stimulate fundamental research into the transport of nanocrystalline bulk semiconductors.

9. Quantum mechanical modeling of single molecule nanodevices (I.I. Oleynik: Materials Physics & Computational Physics). Single organic molecules are actively explored as molecular scale electronic circuitry elements with the prospects of developing new generation of molecular electronic devices that are immensely powerful and efficient yet tiny. This REU project aims at a quantum mechanical investigation of electron and spin transport through such molecules, as well as their relationship to the atomic and electronic properties. An REU student will study atomic and electronic properties of the molecular switch that exhibits hysteresis in the current-voltage (I-V) curve. This switching has been recently observed in a series of experiments, but the fundamental mechanisms of this unusual behavior are currently unknown. First-principles density-functional calculations (DFT) will be performed to investigate the atomic and electronic properties of bipyridyl-dinitro oligophenylene-ethylene dithiol molecular devices. The REU student will also screen several other classes of molecules to determine the existence of two different molecular conformations: one for a neutral molecule, and another for a negative molecular ion. The major focus will be on establishing the structure-property relationship:  how the chemical structure of different functional groups affects the switching behavior of these molecular switches.

10. Understanding PIP2 signaling in cell membranes (S. Pandit: Biomedical/Biophysics & Computational Physics). PI(4,5)P2 is a phospholipid that plays a central role in a wide variety of cellular signaling processes [39,40].  In this project force field parameters for the molecular dynamics simulations of PI(4,5)P2 that are consistent with the modified GROMACS parameters 43A1-S3 will be developed. The parameters will be validated by comparison to NMR studies reported in the literature. Furthermore, long time simulations of hydrated bilayers of mixtures of POPC and  PIP2 lipids will be performed. In these simulations the structural properties of poly-unsaturated chains of PIP2 molecules will be studies along with the electrostatic interactions at the bilayer-water interface that enable PIP2 to play significant roles in the singling processes. An REU student will perform several ab-initio simulations of solvated PIP2 lipids using the software package GAMESS. These simulations will be used to develop the molecular mechanical force fields for the PIP2 lipids. Further, the REU student will assist the graduate students in the development of a multi-scale self consistent mean field theory based model involving PIP2 lipids to study the aggregation behavior and consequent actions as signaling receptors.

11.Finite-temperature properties of nanoscale multiferroics: atomistic exploration (I. Ponomareva: Materials Physics & Computational Physics).
Multiferroic materials that combine one or more "ferroic" properties have attracted a lot of attention due to the promising applications as multifunctional materials. While properties of bulk multiferroics are being intensively investigated, their nanoscale forms are far less understood. The REU student will use state-of-the-art computational tools to study at the atomic scale the finite-temperature properties (such as polarization, magnetization, and the piezoelectric, dielectric, and magnetoelectric constants) of BiFeO3 nanowires. In particular, the transition temperatures, dipole patterns and magnetoelectric coefficients will be obtained. The REU student will learn the state-of-the-art atomic-scale simulation techniques that will be run on supercomputers, and how to collect, analyze, and interpret computational data. Although it is expected that student will work as a member of the research team, he or she will have the opportunity to lead his/her own part of the project that will expose him or her to real scientific research, help promote scientific curiosity, and develop leadership skills. It is expected that the results obtained by the student will become part of a publication and lead to conference presentations.

12. Study of magnetic interactions in core-shell nanostructures (H. Srikanth: Materials Physics).
Magnetic nanostructures have attracted great attention in recent times due to their potential applications in diverse areas such as high-density magnetic recording, sensors, and biomedical diagnostics [47]. When the average particle size of iron oxide nanoparticles (Fe3O4, g-Fe2O3) are reduced below ~20 nm, their collective magnetic behavior show interesting properties such as superparamagnetism in the case of non-interacting particles to possible short-range order determined by dipolar interactions between nanoparticles [48,49]. In this project, the participating REU student will address the nature of surface spin structure in individual nanoparticles, and the inter-particle interactions through systematic experiments and data analysis. This involves (1) chemical synthesis of bare and core-shell nanoparticles, (2) extensive structural characterization by XRD and electron microscopy (SEM, TEM), and (3) DC and AC susceptibility measurements to collect experimental data and analyze the static and dynamic magnetic response of the nanoparticles. After receiving initial training working with graduate students and postdoctoral associates, the undergraduate student will work independently on all aspects of the project.

13. Synthesis of PbS, PbSe quantum dots (QD) and the fabrication of QD/TiO2 nanowire/polymer composite structures for solar energy conversion (S. Witanachchi: Materials Physics & Optics).
The Laboratory for Advanced Materials Science and Technology explores innovations in pulsed laser ablation, plasma processes, and laser-assisted spray processes for the growth of thin films and nanostructures of technologically significant materials including superhard materials, thermoelectric materials, magnetic and multiferroic materials, superconductors, and quantum dots of semiconductors for solar cells. An REU student will work on the synthesis of PbS, PbSe quantum dots (QD) and the fabrication of QD/TiO2 nanowire/polymer composite structures for solar energy conversion. During this project, the student will be introduced to chemical techniques used for the growth of semiconductor quantum dots. They will learn the methods used for structural and physical property characterization.  To fabricate functional devices, these QDs will be incorporated into inorganic or polymeric materials. The student will become familiar with the techniques used for making the hybrid structures, such as laser assisted spray and microwave plasma growth processes.

14. Measuring the conductance spectra of tunnel junctions of strongly correlated transition-metal oxides (G. Woods: Materials Physics).
Magnetic tunnel junctions consisting of the strongly correlated transition-metal oxide Fe3O4 are of considerable interest due to its half-metallic electronic structure. Fe3O4 is widely known for its metal-insulator transition, which is referred to as the Verway transition. In this project, an REU student will fabricate magnetic tunnel junctions consisting of Fe3O4 and a buffer layer using magnetron sputtering. The student will then measure the conductance at the junction to determine the density of states at the Fermi level. Measurement and analysis of the conductance (dI/dV) spectra will be done using the Physical Properties Measurement Device facilities in Dr. Hariharan Srikanth’s laboratory. After successful attempts of fabrication and characterization of the Fe3O4 films, the student will then proceed to fabricate the tunnel junctions. Different barrier layers and counter-electrodes will be tried in order to obtain the best possible conductance measurements. The REU student in this project will obtain extensive experience in the areas of tunneling and magnetron sputtering methods. The work is expected to be publishable in a peer-reviewed journal.

15. Properties of carbon nanostructures from first principles (L. Woods: Materials Physics & Computational Physics).
Carbon nanotubes and graphene ribbons have drawn much interest due to their unique structure and electronic properties, as well as their potential applications in developing different devices, such as energy storage elements, functionalized structures, sensors, biocompatible agents, bearing devices, etc.. Of particular importance is the ability of nanotubes and nanoribbons to interact with different materials, as well as uncovering new ways to modulate their properties under various external stimuli. In this study, the main focus will be to investigate the electronic properties of carbon nanotubes and graphene nanoribbons when various mechanical defects, deformations, and external fields are present. The studies will be performed using state of the art density functional theory (DFT) methods, using computer codes such as VASP and Abinit, which are available at the USF computing facilities. An REU student will learn the basic assumptions of DFT as well as DFT computer codes. The student will also learn how to model realistic nanostructured systems within DFT methods, and extract necessary data from the simulations. In addition, the undergraduate will be exposed to large scale computing systems, and gather experience on how to use them for simulating materials properties.