Bulletin of the American Physical Society
81st Annual Meeting of the APS Southeastern Section
Volume 59, Number 18
Wednesday–Saturday, November 12–15, 2014; Columbia, South Carolina
Session BB: Condensed Matter Physics I |
Hide Abstracts |
Chair: Michel Pleimling, Virginia Tech University Room: Richland I |
Thursday, November 13, 2014 8:30AM - 8:42AM |
BB.00001: Affecting the magnetochemistry of cobalt/gold thin films with organic solvents Fiona Senta Oberbeck-Oxsher, James Adam Fisher, Rahman Mohtasebzadeh, Brett Altschul, Thomas Crawford, Scott Crittenden We show the ability to measure the influence of a number of organic solvents on the magnetic properties of cobalt and colbalt-gold thin films by employing a custom, lithographically patterned planar Hall effect sensor. The magnitude of the observed shift in maximal Hall voltage varies with solvent functional group, scaling with the expected degree of deprotonization. By developing a novel measurement system, we are able to perform all experiments under standard conditions and apply the solvent without moving the sample out of the instrument, which eliminates a significant amount of error compared to previous measurements. [Preview Abstract] |
Thursday, November 13, 2014 8:42AM - 8:54AM |
BB.00002: Robust critical current density in applied magnetic fields in 5 $\mu$m thick, SmBa$_{2}$Cu$_{3}$O$_{7-\delta}$ based superconducting wires A.O. Ijaduola, F. List, H.-S. Kim, S.-S. Oh, A Goyal We report the magnetic field and temperature dependence of the critical current density \textbraceleft $J_{c} (H)$ and$J_{c} (T)$\textbraceright flowing in a 5 $\mu$m thick sample of SmBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (SmBCO) film. The film is a coated conductor (CC) deposited on an IBAD-MgO textured metallic template. For a range of intermediate fields, we find $J_{c} \alpha$ $H^{-\alpha}$ with values of $\alpha $ between 0.44 and 0.49. These values are lower than those reported for other CC in the literature. The sample also has higher $J_{c}$ values when compared with other wires with similar thicknesses. Such high-$ J_{c}$ wires should find applications in large-scale energy applications of high-temperature superconductors. The temperature dependence of $J_{c} $ at self-field and different applied fields is also analyzed. [Preview Abstract] |
Thursday, November 13, 2014 8:54AM - 9:06AM |
BB.00003: Fourier Analysis of Lowest Normal-Mode Functions for Beams and Plates: Implication for Graphene W. Eugene Collins, Ronald E. Mickens The mechanical properties of grapheme sheets and tubes can be modeled by a very nonlinear, integral-partial differential equation. For one (effective) space dimension, the solution u(x,t) is generally written as a product of the mode shape, $\phi $(x), and a mode amplitude, $\phi $(t), i.e., u(x,t)$=\phi $(x)$\psi $(t), where $\phi $(x) is taken to be $\phi $(x)$=$sin($\pi $x/L). This ansatz allows the determination of an ordinary differential equation for $\psi $(t), which turns out to be the Duffing equation. However, the (constant) coefficients appearing in the Duffing equation depend on exactly which specific function is selected for $\phi $(x). Since these coefficients are used to calculate various mechanical features, it follows that the use of different $\phi $(x) can produce different estimates for the related mechanical properties. We consider the case of a rigidly clamped beam, defined by the conditions \begin{equation} \phi (0)=\phi (L)=0, \phi' (0)=\phi' (L)=0, \end{equation} and compare its Fourier series representations to the functions \begin{equation} \phi 1(x)=\sin(\pi x/L), \phi \textunderscore \{^2\} \textbraceright (x)=x(L-x). \end{equation} An example of a mode function satisfying Eq.(1) is \begin{equation} \phi 3(x)=x^2(L-x)^2. \end{equation} Background information on these issues is given in I. Kovavic and M. J. Brennan: The Duffing Equation (Wiley, 2011), sections 2.8 -- 2.10. [Preview Abstract] |
Thursday, November 13, 2014 9:06AM - 9:18AM |
BB.00004: Parallel Critical Fields and Inductive Critical Currents in Nb/Cr bilayers Phillip Broussard, Amy Davis Measurements of parallel critical field and inductive critical currents in Nb/Cr bilayers have been carried out. The films were grown by magnetron sputtering onto room temperature silicon substrates from separate sources. Bilayers with either varying Nb or Cr layer thicknesses were studied. Parallel critical fields were measured using resistive method and inductive critical currents were measured using a third harmonic technique at 1 kHz. We see evidence of 2D behavior in the parallel critical fields and the results indicate that the moderately dirty limit of V. Kogan (Phys. Rev. B 32,139 (1985)) needs to be taken into account. $J_{c}$ varies as $(1-t)^{\gamma}$ with $\gamma$ being $\approx$ 1.4 for constant Nb thickness bilayers, but decreasing as the Nb thickness decreases. (Here $t$ is the reduced temperature, $T/T_{c}$). Our pure 50nm Nb film had a $T_{c}$ of 9.0 K with an inferred $J_{c}(0)$ of 22 MA/cm$^{2}$. There is a decrease in $J_{c}(0)$ as the Cr layer increases, but the question of whether this is due to an actual reduction or if the superconductivity is remaining in the Nb layer only is still open for these films. This will be discussed. [Preview Abstract] |
(Author Not Attending)
|
BB.00005: Quantum model of capacitance at the nanoscale Jun-Qiang Lu In this talk, I will present the difference in modeling steady and dynamic electronic transport properties of nanomaterials and propose a quantum model to measure capacitance of nanomaterials. [Preview Abstract] |
Thursday, November 13, 2014 9:30AM - 9:42AM |
BB.00006: Band Parameters of Two-Dimensional Materials: Phosphorene and Silicene Lok Lew Yan Voon, Alejandro Lopez Bezanilla, Jianwei Wang, Yong Zhang, Morten Willatzen The method of invariant is used to derive effective Hamiltonians in the presence of strain and external fields for phosphorene and silicene as examples of two-dimensional materials with and without a band gap. The band structure parameters have been obtained by fitting to density-functional theory calculations. [Preview Abstract] |
Thursday, November 13, 2014 9:42AM - 9:54AM |
BB.00007: Alternative Method of Electrospraying for Scalable Deposition of Nanomaterials Kalyan Kanakamedala, Theda Daniels-Race There is a great deal of interest in various room temperature methods for the deposition of nanomaterials. Among these, Electrospraying has, in the last decade, garnered attention due to its simplicity and versatility. In this method, a liquid droplet is subjected to a high voltage (kV range) such that charge density on the droplet dominates the surface tension, causing the droplet to breakdown. This interaction is repeated to produce micron size droplets until a Taylor cone or ``spray'' of droplets is formed that, in turn, can be deposited uniformly across a substrate. Electrospraying has been used for the deposition of polymers, metals and insulators alike, given the versatility of the method. However, this method is also limited due to scaling issues caused by complexities of the electric fields across multiple nozzles, as needed to create the spray itself. In this work, we investigate an alternative method by which to scale the electropsraying process using a free solution surface. Effects of parameters such as solution viscosity, distance between the solution and target, and voltage variations are investigated with respect to their effect on the final deposited film. Our results demonstrate that generation of the spray from the free surface removes several barriers to uniform deposition in comparison to other methods of coverage. [Preview Abstract] |
Thursday, November 13, 2014 9:54AM - 10:06AM |
BB.00008: Mechanical Properties of Hydrogel Beads Keely Criddle, Thomas Benns, Dan Shorts, Klebert Feitosa Disordered dense packing of bubbles, droplets and grains form fragile solids that can withstand small stresses by virtue of system-wide force~chains that lock the system into a jammed state. The nature of force chains in soft materials has been the subject of intense research, but despite much effort, a deep understanding of the jamming transition remains elusive. In this experiment we study the mechanical properties of hydrogel beads to explore these particles as force~chain transducers in densely packed systems. The experiment consists of uniaxial compression of hydrogel beads under a known force, measuring the strain and the radius of the contact area of the bead. A linear relationship exists between the contact radius and the strain, and two separate regimes determine the relationship between the force and the strain. Using the relationships found, a universal power law is being determined to describe the force as a function of the contact radius of the beads. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700