Research Experiences for Undergraduates
Summer 2017

Vanderbilt University
Physics & Astronomy

Research Projects: Condensed Matter, Atomic, Molecular, Optical, and Nano Physics

Nonlinear optics in metal/metal-oxide nanostructures
(Prof. Richard Haglund)
An REU student can work in Haglund's group on an investigation of ultrafast optical switching in nanostructures that incorporate metal nanoparticles and vanadium dioxide. Depending on the nonlinear optical effect to be studied (e.g., second-harmonic generation, nonlinear refraction), model nanostructured materials are prepared using focused ion-beam machining or electron-beam or colloid-mask lithography; the metal and vanadium dioxide deposition is done by either evaporation or pulsed laser deposition. The semiconductor-to-metal phase transition in vanadium dioxide is then initiated by heating or a fast laser pulse; the temporal and spectral responses are studied by ultrafast pump-probe spectroscopy, confocal dark-field microscopy, scanning near-field optical microscopy (SNOM), and single-nanoparticle Raman spectroscopy. REU students will have the opportunity to learn about clean-room technology; lithographic fabrication of metal/metal-oxide nanostructures; thin-film deposition; materials characterization by atomic-force and scanning-electron microscopies; and optical spectroscopy and microscopy using lasers emitting at wavelengths from the visible to the mid-infrared and at pulse durations as short as 20 fs.

Computational Materials Physics and Nanoscience
(Prof. Sokrates Pantelides, Prof. Kalman Varga)

Members of Pantelides' group carry out first-principles calculations of electronic and structural properties of various materials. An assortment of computer codes are available that REU students can easily learn how to run. As an entry point, a student could reproduce some well-known results such as energy bands for crystalline Si, determination of the lattice constant of Si, determination of the structure of a nanocluster (small molecule), and so on. The student gets to appreciate the quantum mechanics that underlie the calculations. Once comfortable with the codes, the student will be given a real problem that has a good likelihood for either completion or at least significant progress within the available time. A problem relating to the physics of nanoclusters is likely. There are many options and the determination will be made at the time the student is accepted to participate. As an example, a previous undergraduate student tackled the problem of how an aspirin molecule interacts with a local site at a protein, to probe the physics of how aspirin works in the human body. Another student participated in research on how a single La atom binds on the surface of alumina, a problem that relates to the catalytic properties of alumina. The group is also working on several problems in nanocatalysis with gold nanoclusters on different substrates. The main activity of Kalman Varga's group is computational modeling and simulation of electronic and transport properties of nanostructures interacting with short strong laser pulses. The group is interested in time-dependent electron dynamics including Coulomb explosion, Petahertz electronics, attochemistry, time dependent band structure engineering, and ultrafast energy transfer processes. The group is also actively working on studying electron transport processes in nanostructures using novel computational tools. Undergraduate students interested in computational physics, modelling, state of art simulations are encouraged to joint the group.

Ultra-Fast Laser Studies of Surfaces and Interfaces
(Prof. Norman Tolk)
The Tolk group studies ultra-fast tunable laser induced electronic and vibrational excitation at surfaces and interfaces. REU students will have the opportunity to be actively engaged in one or more of the following research thrusts: (A) Non-thermal resonant photodesorption of hydrogen from silicon and diamond crystal surfaces, using the Vanderbilt Free-Electron Laser. This novel and unanticipated effect was reported in the May 2006 issue of the magazine Science. This research effort is not only fundamental but also has very exciting possible applications including low-temperature growth of silicon and diamond crystals, hydrogen storage and room temperature refining. (B) Spin Dynamics of Ultra-Fast Laser Photoinduced Magnetization in Expitaxial GaMnAs. We have initiated a study of the dynamics of photoinduced magnetization in ferromagnetic Ga1-xMnxAs (x=0.05) by time-resolved polar Kerr rotation over a wide range of temperatures. Measured spin relaxation times were found to vary from tens to hundreds of picoseconds. The GaMnAs magnetic semiconductor system has received considerable attention in recent years because it is anticipated that it will play a major role in developing future spin-based devices. (C) Near-bandgap wavelength-dependent studies of long-lived traveling coherent longitudinal acoustic phonon oscillations in GaSb/GaAs systems. The oscillations arise from a photo-generated coherent longitudinal acoustic phonon wave, which travels from the top surface of GaSb across the interface into the GaAs substrate, thus providing information on the optical properties of the material as a function of time/depth. Wavelength-dependent studies of the oscillations near the bandgap of GaAs indicate strong correlations to the optical properties of GaAs.

 

 

 

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Program details:

  • Ten weeks
  • Stipend $5,000
  • Travel, housing, meals provided

Application deadline:
March 4

Late application deadline:
March 15

Program dates:
May 29 - Aug 5