Four-Year College Faculty-Student Team Fellowships Program
Prof. Julian Velev and student Carlos Litovich Hernandez
(left: Gradstudent Juan López-Encarnación)
University of Puerto Rico - Río Piedras
worked with Evgeny Tsymbal, Physics.
"Our work this summer was directed towards investigation of the effect of lateral strain on ferroelectricity for various materials of practical interest. Strain engineering, by growing epitaxially materials on substrates with different lattice constants, has proven to be a powerful method for stabilizing and enhancing the ferroelectric properties of these materials. We performed electronic structure calculations from first-principles based on density functional theory. The effect of lateral strain was simulated by constraining the lattice constant in the plane and relaxing the resulting forces in the third dimension. Then electric polarization was calculated using the Berry phase method."
Prof. Yung Huh and student Matthew Allison
South Dakota State University
worked with David Sellmyer, Physics.
"Dr. Yung Huh and his student Matthew Allison from the South Dakota State University are working on magnetic properties of transition metal oxide nanoparticles and transport study of FePt thin films. They are interested in the size-dependent magnetic responds of transition metal oxides whose particle size ranges from 5 nm to 18 nm. The normal and abnormal Hall effects are being investigated in FePt thin films with systematically varying Fe concentration. They are using Magnetron Sputtering Deposition System for layered thin film preparation, SQUID magnetometer and Vibrating Sample Magnetometer for magnetic characterization, and X-ray diffraction and SEM for structural study."
Prof. Luis Rosa and student Rosette Gonzalez
University of Puerto Rico - Humacao
worked with Peter Dowben, Physics.
"Our work this summer consisted on the adsorption of isomers of 1,2-diodobenzene, 1,3-diodobenzene and 1,4-diodobenzene on ferroelectric co-polymer poly(vinylidene fluoride with trifluoroethylene) P(VDF-TrFE) thin film substrates. The ferroelectric co-polymer P(VDF-TrFE) films were prepared by Langmuir-Blodgett deposition techniques on a graphite substrate. Selective adsorption from the gas phase of the diodobenzenes has been observed on the ferroelectric co-polymer surface. The molecular preferential orientation and substrate interactions upon adsorption seems to be influence by there strong dipole-dipole interactions and molecular structure."
Prof. Mark Plano Clark and student Paul Garcia
Doane College (Crete, NE)
worked with Axel Enders, Physics.
"This was the second summer on this project for student Paul Garcia and Prof. Mark W. Plano Clark, Doane College. We continued to work on the development of an inexpensive low-voltage room-temperature atmospheric-pressure scanning tunneling microscope (STM). Our hope is to produce an affordable easy-to-use table-top STM that can be used by high school and college teachers to give their students hands-on experience with nanotechnology in their physics courses. To this end we have designed and built a novel piezoelectric actuator that replaces the traditional tube type actuators used on high-end STMs. Our actuator uses inexpensive flat sheets of piezo material that are cemented to stainless steel caps in a rectangular box that provides both the necessary z-motion of the tunneling tip as well as the x- and y-scan motion. With 16-bit digital-to-analog and analog-to-digital converters, we could have x, y, and z resolutions of around 30 pm if we can control the noise. The electronic noise requires careful design and of the amplifiers and we have demonstrated electronic noise levels as low as 50 pm without full shielding. Mechanical vibrations are damped with the use of a stack of aluminum plates separated by half loops made from o-rings. We have achieved course motion of our STM tip using inertial slip/stick motion and speeds of approximately 0.2 mm/s. We have produced a transimpedance amplifier with feedback to maintain a constant tunneling current (constant height above the surface being studied) as well as amplifiers to convert the small signal levels from the digital-to-analog converters to the ±18V for x/y scanning and for the z-motion. We also have all the components to build a digital signal processing (DSP) system with LCD screen and touch controller for a full data acquisition system. This is an ongoing project! To speed development we have decided to obtain a commercial DSP system that is specifically designed to work with the open source STM control software package, GXSM. This DSP controller costs approximately $1000 which brings the cost of our system to approximately $1200 which is still within reach of many high school teachers and most college physics faculty."