Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session B3: Undergraduate Research - Society of Physics Students II |
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Sponsoring Units: SPS Chair: Daniel Golombek, Society of Physics Students- American Institute of Physics Room: 107 |
Monday, March 3, 2014 11:15AM - 11:27AM |
B3.00001: Gold and Gallium Nanoparticle Growth on Silicon (100) Rees Madsen, Hunter L. Brown, Sadie Ames, J. Leland Rasmussen, Samuel Tobler Nanoparticles are used for various applications in today's research. Some researcher's interests involve using the nanoparticles to grow silicon nanowires on a silicon substrate. Before growing nanowires can be accomplished a study must be made of the formation of nanoparticles. Most often the metal used to make the nanoparticles is gold. In this study both gold and gallium were used to make the nanoparticles, by thermal evaporation. The gold and gallium nanoparticles were grown on silicon (100). Between one to three monolayers of material was added to the substrate, with the particle sizes ranging from 0.5 microns to 3 microns in diameter. Densities of nanoparticles varied based on the time of growth and on the intensity of the source. The variable sizes were seen with sample temperatures between 700 C and 900 C measured using a disappearing filament optical pyrometer. The growth process occurred at pressures below 3e-7 Torr. This presentation will summarize the growth process and show the similarities and differences between the two metals. [Preview Abstract] |
Monday, March 3, 2014 11:27AM - 11:39AM |
B3.00002: Optimization of Thick, Large Area YBCO Film Growth Through Response Surface Methods J. Porzio, C.H. Mahoney, M.C. Sullivan We present our work on the optimization of thick, large area YB$_2$C$_3$O$_{7-\delta}$ (YBCO) film growth through response surface methods. Thick, large area films have commercial uses and have recently been used in dramatic demonstrations of levitation and suspension. Our films are grown via pulsed laser deposition and we have optimized growth parameters via response surface methods. Response surface methods is a statistical tool to optimize selected quantities with respect to a set of variables. We optimized our YBCO films' critical temperatures, thicknesses, and structures with respect to three PLD growth parameters: deposition temperature, laser energy, and deposition pressure. We will present an overview of YBCO growth via pulsed laser deposition, the statistical theory behind response surface methods, and the application of response surface methods to pulsed laser deposition growth of YBCO. Results from the experiment will be presented in a discussion of the optimized film quality. [Preview Abstract] |
Monday, March 3, 2014 11:39AM - 11:51AM |
B3.00003: Synthesis and characterization of the physical properties of \textit{RE}$_{3}$TiSb$_{5}$ (\textit{RE} $=$ La, Ce) Tracy Stevenson, Chantal Douglas, Daniel Jackson, Derrick VanGennep, James Hamlin \textit{RE}$_{3}$TiSb$_{5}$ (\textit{RE}$=$ La, Ce) is synthesized to investigate the physical properties and test for superconductivity. Ce$_{3}$TiSb$_{5}$ was synthesized using flux growth in both Sn and Zn fluxes while La$_{3}$TiSb$_{5}$ was synthesized using Sn flux. Magnetic, resistive, and heat capacity measurements all indicate that neither of these compounds are superconducting. Based on our results La$_{3}$TiSb$_{5}$ is non-magnetic and Ce$_{3}$TiSb$_{5}$ has an antiferromagnetic phase transition near 5 K. Neither compound exhibits typical metallic transport behavior. This is in contradiction to previous results. [Preview Abstract] |
Monday, March 3, 2014 11:51AM - 12:03PM |
B3.00004: Optimization of growth conditions for (La$_{1-y}$Pr$_{y})_{1-x}$Ca$_{x}$MnO$_{3}$ thin films on annealed oxide substrates Brian Schaefer, Daniel Grant, Amlan Biswas Consistent growth of flat, epitaxial thin films is essential for uncovering the unique transport characteristics of rare-earth manganite systems. We have developed pulsed laser deposition growth conditions for (La$_{1-y}$Pr$_{y})_{1-x}$Ca$_{x}$MnO$_{3}$ (LPCMO, $y =$ 0.4, 0.5, 0.6) thin films on annealed NdGaO$_{3}$ (NGO) and SrTiO$_{3}$ (STO) substrates. The extra annealing step for NGO and STO produces atomically flat substrates with well-defined terraces of unit cell step height. Films grown on these annealed substrates demonstrate better lattice matching compared to films grown on as-received substrates. Consequently, annealing substrates before film growth leads to higher quality thin films with a more controllable thickness. We demonstrate that these optimized growth parameters yield LPCMO thin films that are also atomically flat, as confirmed by atomic force microscopy. We are using these thin films to restrict phase growth to reduced dimensions and to study the origin of thermodynamic phase competition due to first order transitions in manganites. [Preview Abstract] |
Monday, March 3, 2014 12:03PM - 12:15PM |
B3.00005: Synthesis and characterization of hydrothermally grown ZnO nanomaterials for biomedical applications Austin Shearin, Anagh Bhaumik, Adam Wanekaya, Robert Delong, Kartik Ghosh Nanomaterials have been of recent importance in the biomedical field due to their use in drug delivery applications, magnetic resonance imaging, and cell separation. Intrinsically nanomaterials of ZnO are having low cytotoxicity and genotoxicity which is suitable for several biomedical applications. The aim of this work has been to synthesize high quality ZnO nanostructures using hydrothermal process with varied growth parameters. X-ray diffraction studies on the high quality synthesized materials confirmed the hexagonal crystal structure as well as the nano-crystallite size of ZnO. Raman spectroscopy has been done on the nanostructured ZnO to understand the different phonon modes present in the molecule. Scanning electron microscopy was used to observe shape and size of the synthesized nanomaterials. Future work to be done is to study interaction kinetics between ZnO nanostructures with biomolecules such as ATP, RNA and protein. [Preview Abstract] |
Monday, March 3, 2014 12:15PM - 12:27PM |
B3.00006: Colossal piezoresistance in phase separated manganites Maria Viitaniemi, In Hae Kwak, Amlan Biswas Hole-doped manganese oxides (manganites) exhibit piezoresistance, which is defined as a change in electrical resistance as a function of strain. At low temperatures and for particular chemical compositions, manganites can also exist in a thermodynamic phase separated state. In this phase separated state, piezoresistance can increase dramatically, a phenomenon called colossal piezoresistance (CPR). By modifying an existing low temperature probe and measurement setup, we measured the resistance of thin films of the manganite (La$_{\mathrm{1-y}}$Pr$_{\mathrm{y}})_{\mathrm{1-x}}$Ca$_{\mathrm{x}}$MnO$_{\mathrm{3}}$ (LPCMO). We used a three-point beam bending method to control the compressive or tensile strain on these thin films. The resulting change in resistance and thermal hysteresis reveals phase separation and CPR in LPCMO. We are performing similar tests on La$_{\mathrm{0.7}}$Sr$_{\mathrm{0.3}}$MnO$_{\mathrm{3}}$ (LSMO) thin films. LSMO is of interest to us because it may be possible to induce phase separation in this material at room temperature and above. [Preview Abstract] |
Monday, March 3, 2014 12:27PM - 12:39PM |
B3.00007: Low-cost Flexible Memristor Fabrication Inna Kirilyuk, Nadine Gergel-Hackett Memristors are two-terminal electronic devices that exhibit unique electrical characteristics, including nonvolatile electrical switching between resistive states. These unique electrical characteristics may enable the use of memristors as logic and/or memory components in novel computer architectures. Flexible memristors have been shown to not only exhibit the electrical characteristics unique to the devices, but are also operable after 4,000 flexes, require voltages less than 10 V, show on:off ratios \textgreater 10,000:1, are nonvolatile for up to 14 days, and are fabricated at room-temperature with sol-gel solution processing. To increase accessibility to the technology and decrease production costs, we are developing methods of flexible memristor fabrication that are low-cost compared to current conventional fabrication. This low-cost fabrication includes exploring alternative materials and processes for device contacts, synthesizing and storing titanium dioxide sol-gel using standard wet chemistry tools without the use of a glove box, and using a low-cost spinner to spin sol-gel onto devices. The fabrication is performed entirely in an undergraduate lab setting by undergraduate students. [Preview Abstract] |
Monday, March 3, 2014 12:39PM - 12:51PM |
B3.00008: Electrical and structural Characterization of Ba(Sc$^{3+}$, Sb$^{5+})_{\mathrm{y}}$Ti$_{0.90}$O$_{3}$ with y $=$ 0.05 and 0.10 Julio Cantu, Jerry Contreras, Daniel Potrepka, Frank Crowne, Arthur Tauber, Steven Tidrow Ba(Sc$^{3+}$, Sb$^{5+})_{\mathrm{y}}$Ti$_{0.90}$O$_{3}$, with y $=$ 0.05 and 0.10, is investigated through temperature dependent electrical and structural characterization. The material is electrically characterized from 10 Hz to 2MHz for dielectric constant, tunability, dissipation factor and figure of merit over the temperature range of -50 $^{\circ}$C to 125 $^{\circ}$C. In addition, lattice parameters and structural changes of the material are reported as a function of temperature as obtained using x-ray diffraction and Rietvield refinement. Properties of these electric-field tunable materials are discussed in terms of ferroelectrics, non-relaxor versus relaxor behavior, and a ferrorelectric dipole-like glass state. [Preview Abstract] |
Monday, March 3, 2014 12:51PM - 1:03PM |
B3.00009: Electrical and Structural Characterization of Ba(Y, Ta)$_{\mathrm{x}}$ Ti$_{\mathrm{1-2x}}$O$_{3}$ With x $=$ 0.025 and 0.05 Jerry Contreras, Steven C. Tidrow, Daniel Potrepka, Frank Crowne, Arthur Tauber Ba(Y, Ta)$_{\mathrm{x}}$ Ti$_{\mathrm{1-2x}}$O$_{3}$, with x $=$ 0.025 and 0.05, is investigated through temperature dependent electrical and structural characterization. The material is electrically characterized from 10Hz to 2 MHz for dielectric constant, tunability, dissipation factor and figure of merit over the temperature range -50 $^{\circ}$C to 125 $^{\circ}$C. In addition, lattice parameters and structural changes of the material are reported as a function of temperature as obtained using x-ray diffraction and Rietveld refinement. Properties of these electric-field tunable materials are discussed in terms of ferroelectrics, non-relaxor versus relaxor behavior, and a ferroelectric dipole-like glass state. [Preview Abstract] |
Monday, March 3, 2014 1:03PM - 1:15PM |
B3.00010: Electrical and Structural Characterization of Ba(In,Sb)$_{y}$Ti$_{1-2y}$O$_{3}$ With y $=$ 0.05 and 0.10 Oscar Guerrero, Jerry Contreras, Daniel Potrepka, Frank Crowne, Aurthur Tauber, Steven Tidrow Ba(In,Sb)$_{0.05}$Ti$_{0.90}$O$_{3}$ and Ba(In,Sb)$_{0.10}$ Ti$_{0.80}$O$_{3}$ are investigated through temperature dependent electrical and structural characterization. The material is electrical characterized from 10 Hz to 2 MHz for dielectric constant, tunability, dissipation factor and figure of merit over the temperature range -50 $^{\circ}$C to 125 $^{\circ}$C. In addition, lattice parameters and structural changes of the material are reported as a function of temperature as obtained using x-ray diffraction and Rietveld refinement. Properties of these electric-field tunable materials are discussed in terms of ferroelectrics, non-relaxor versus relaxor behavior, and a ferroelectric dipole-like glass state. [Preview Abstract] |
Monday, March 3, 2014 1:15PM - 1:27PM |
B3.00011: Interfacial Layer Optimization in Organic Photovoltaics Joshua Litofsky, Evan Lafalce, Xiaomei Jiang Organic photovoltaic devices (OPVs) based on benchmark $\pi -$conjugated polymer polythiophene and electron acceptor PCBM are made up of a sandwich-like structure of multifunctional layers. Interfacial layers (IL) facilitate charge transport between the charge generation layer and the electrodes and enhance charge extraction. Optimizing the IL thus provides one mean of maximizing the efficiency of OPVs. Various electron transport layers such as ZnO and LiF were used, and hole transport layers included PEDOT:PSS and V$_{\mathrm{2}}$O$_{\mathrm{5}}$. Two different device architectures were explored: conventional structure with ITO serving as an anode and inverted structure when ITO acts as a cathode. Using various deposition techniques, we worked to optimize IL thickness and film formation methods. By analyzing device shunt and series resistances using a standard diode equation, we were able to identify the optimal parameters for device performance. The combination of thin IL with electrodes of appropriate work function yielded much better results compared to the control device with no IL. We can use these results and techniques to further optimize future OPV devices based on other novel material systems. This work was supported by the NSF REU grant {\#} DMR-1263066: REU Site in Applied Physics at USF. [Preview Abstract] |
Monday, March 3, 2014 1:27PM - 1:39PM |
B3.00012: Estimating Ultra-High Energy Cosmic Ray Data as seen from the JEM-EUSO Fluorescence Detector for the planned space based JEM-EUSO detector Jeremy Fenn, Lawrence Wiencke Ultra-high energy cosmic rays (UHECRs) are subatomic particles with energies above 10$^{18}$ eV. UHECRs are of interest because they are the highest energy particles known to exist. Their source(s), compositions, and the acceleration mechanisms to produce them with energies beyond 10$^{20}$ eV remain unknown. The Pierre Auger Observatory, located in Argentina, is the world's largest UHECR observatory. It is one of the few a hybrid detectors in the world that combines surface (SD) and fluorescence (FD) detectors. The hybrid detection system is advantageous as it provides a more accurate reconstruction of the incoming cosmic ray's energy and trajectory as it travels through the atmosphere. However, even with the advantage of a hybrid detector, the Pierre Auger has limitations being a ground based observatory. The next generation in UHECR detection is the planned JEM-EUSO mission. The JEM-EUSO mission will consist of a fluorescence detector telescope attached to the International Space Station (ISS). The JEM-EUSO detector is expected to receive an exposure level to UHECRs many times that of the Pierre Auger Observatory by viewing a much larger volume of the atmosphere. In this presentation, I will discuss how data from specific UHECRs collected by the Pierre Auger Observatory is analyzed and altered to estimate what their signatures would look like from space at the planned JEM-EUSO detector. [Preview Abstract] |
Monday, March 3, 2014 1:39PM - 1:51PM |
B3.00013: Aiming lasers into the sky from the Pierre Auger Cosmic Ray Observatory at astrophysical objects of interest Steven Hackenburg, Lawrence Weincke Ultra High Energy Cosmic Rays at are the highest energy particles known to exist, they are also some of the rarest with a flux less than 1 per century per square km. To study cosmic rays the worlds largest cosmic ray observatory, the Pierre Auger Observatory was built and completed in 2008. The data collected from the observatory hints at a correlation between cosmic ray arrival directories on earth and certain active galaxies. The Central Laser Facility (CLF) is located in the middle of the observatory, which recently had upgrades added on June 2013. The CLF has a UV pulsed laser. If the laser is fired into the atmosphere, a laser track is created that is similar to the signatures left behind by cosmic ray events in the atmosphere. Hence, the laser is used to calibrate the detectors at the observatory and create benchmark data. An example of benchmark data is artificial sky maps, consisting of reconstructed laser tracks, pointed toward Galaxies of interest. This presentation will describe the technique of using the lasers as a benchmarking tool to create artificial sky maps. Improvements to the timing and pointing accuracy of the method will also be discussed. [Preview Abstract] |
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