Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session C67: Undergraduate Research IIIFocus Undergraduate
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Sponsoring Units: APS/SPS Chair: Brad Conrad, American Institute of Physics Room: BCEC 050 |
Monday, March 4, 2019 2:30PM - 2:42PM |
C67.00001: Neuronal dynamics on patterned substrates measured by fluorescence microscopy Joao Marcos Vensi Basso, Cristian Staii Geometrical features are known to be very important in neuronal growth and the formation of neuronal networks. We present experimental and theoretical investigations of axonal growth and dynamics for neurons cultured on patterned surfaces. We utilize fluorescence microscopy to image the axonal dynamics and show that these substrates impart a strong directional bias to neuronal growth. We model axonal dynamics using a general stochastic model and use this framework to extract key dynamical parameters. These results provide novel insight into how geometrical cues influence neuronal growth and represent important advances toward bioengineering neuronal growth platforms. |
Monday, March 4, 2019 2:42PM - 2:54PM |
C67.00002: ABSTRACT WITHDRAWN
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Monday, March 4, 2019 2:54PM - 3:06PM |
C67.00003: Exact diagonalization RIXS studies of the doped 1d t1-t2-J model at the O K-edge Gregory Price, Umesh Kumar, Kenneth C Stiwinter, Steven Johnston, Trinanjan Datta
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Monday, March 4, 2019 3:06PM - 3:18PM |
C67.00004: Hybrid Exciton in Semiconductor Nanorod Coated by an Organic Shell Emily Sutherland, Que Huong Nguyen We report a theoretical research on Wannier-Frenkell hybrid exciton in a semiconductor nanorod coated by an organic shell. |
Monday, March 4, 2019 3:18PM - 3:30PM |
C67.00005: Solving for Multiple Bound States Contained Within the Continuum of the Friedrichs Model Alexander Glickfield, Gonzalo Ordonez The Friedrichs model consists of an interaction between the discrete states of a quantum system (say, a set of atoms) and a set of continuous states. The interaction produces a resonance, resulting in complex eigenenergies. The resonance appears as a pole of the analytic continuation of the reduced resolvent corresponding to the interacting Hamiltonian. As the imaginary component approaches 0, the eigenstate's lifetime becomes infinite, forming a bound state in the continuum. We solve for a set of parameters that generates multiple resonances with infinite lifetime within the model. |
Monday, March 4, 2019 3:30PM - 3:42PM |
C67.00006: Static and dynamic properties of a one-dimensional spin-1/2 system Aviva Shooman, Lea Santos We study the static properties and the dynamics of a quantum system described by a one-dimensional spin-1/2 model with nearest neighbor couplings. We analyze the eigenvalues and the eigenstates of this model with different chain sizes and different boundary conditions. From this analysis, we are able to anticipate how fast the excitations should spread over the chain. The more delocalized the eigenstates are, the faster the excitations should move along this chain. Next, we study the evolution of the system numerically and confirm our predictions. All our Mathematica codes are available upon request. |
Monday, March 4, 2019 3:42PM - 3:54PM |
C67.00007: Charge Density Wave States in CeTe2 Burhan Ahmed, Bishnu Sharma, Manoj Singh, Boning Yu, Philip Walmsley, Ian R Fisher, Michael C Boyer Charge density wave (CDW) states are formed in some, typically low-dimensional, materials below a transition temperature, TCDW. The transition of a material into a CDW state leads to the formation of a periodic charge modulation, a periodic lattice modulation, and the opening of an energy gap. While CDW states exist in many condensed matter systems, there is much to be known about the driving-mechanisms for these states as well as how these states coexist with other phases such as superconductivity. Here we present our work using scanning tunneling microscopy (STM) to study CDW states in CeTe2, a rare-earth ditelluride with a CDW transition well over room temperature. In particular, we will present our work on quantifying nanoscale strain in CeTe2 in an effort to better understand the local properties of the CDW states we observe. |
Monday, March 4, 2019 3:54PM - 4:06PM |
C67.00008: Development and characterization of an improved wireless centrifuge force microscope using acrylate microspheres and silicon nitride membranes Logan Fairgrieve-Park, Tristan Stark, David Fortin, Amy Au, Michael Woodside, Noel Q Hoffer, Mark Freeman Centrifuge force microscopy allows for multiple concurrent single molecule measurements which cannot be achieved using more traditional experimental platforms. By altering the design of a wireless centrifuge force microscope (CFM) created at the University of Albany [1], we have developed an improved model. By upgrading the integrated single board computer to a Rock64 (Pine Microsystems Inc.) with a USB 3 connector we can achieve higher image transfer rate. Additionally, we describe a novel technique for CFM calibration. By adhering acrylate microspheres of multiple sizes to a silicon nitride membrane (Norcada) [2], we are able to quantify membrane displacement as a function of centripetal force. This technique could be extended to other CFMs as a method for calibration of the centrifuge and optics. Upon completion of the experimental use of the CFM, it will be integrated into a senior undergraduate physics lab course at the University of Alberta. |
Monday, March 4, 2019 4:06PM - 4:18PM |
C67.00009: Surface Species in Graphene Liquid Cells for Transmission Electron Microscopy Nathan Rosenmann, Lopa Bhatt, Arunachala Nutalapati, Soomin Park, Jake R Jokisaari, Mark Schlossman, Robert Klie The behavior of nanoparticles in liquid is important to a wide variety of fields, from medical to environmental. The aggregation of such particles is an important factor for nanoparticle removal during processes such as water purification. However, due to their size, nanoparticles in solution are difficult to characterize directly by optical or x-ray based methods. An effective method to observe nanoparticles in liquid is using the scanning transmission electron microscope(STEM) combined with graphene-based liquid cells(GLC). |
Monday, March 4, 2019 4:18PM - 4:30PM |
C67.00010: Using the "EasySpin" toolbox in MATLAB to model the magnetism of clusters and chains Orlando Trejo, Mark Meisel, Erik Cizmar The “EasySpin” toolbox [1], which runs within MATLAB software, was designed as an analysis tool of EPR spectra. Yet, the 4.5 version of the toolbox was used to generate algorithms that allowed the isothermal magnetization and temperature-dependent magnetic susceptibility of clusters to be modelled [2,3]. Now, the 5.2 version contains library functions that allow these magnetic properties to be calculated. The first step was to compare the results of the new version with the published work [2,3]. Next, the magnetic response of [Mn3O(O2PPh2)3(mpko3)] [4] was simulated with “EasySpin”, and these results will be discussed. Ultimately, the goal is to simulate the low-field, temperature-dependent, magnetic susceptibility reported for an S = 1, one-dimensional spin chain, [Ni(HF2)(3-Clpy)4]BF4 [5] with nearest-neighbor interactions, J, and single-ion anisotropy, D. These results will be presented for chain lengths of at least 7 spins. |
Monday, March 4, 2019 4:30PM - 4:42PM |
C67.00011: Switching of biaxial synthetic antiferromagnets: a micromagentic study Michael Ackermann, Satoru Emori We simulate the switching behavior of nanoscale synthetic antiferromagnets, inspired by recent experimental progress in spin-orbit-torque switching of crystal antiferromagnets. The synthetic antiferromagnet consists of two ferromagnetic thin films with in-plane biaxial anisotropy and interlayer exchange coupling, which leads to enhanced stability against external field perturbations compared to single-layer ferromagnets. Switching between the orthogonal easy axes is enabled by current-induced Rashba spin-orbit fields from the opposite surfaces of the synthetic antiferromagnet. The use of the field-like spin-orbit torque allows for faster switching with increased Gilbert damping, without a significant detrimental increase of the threshold switching current density. Our results point to the potential of these model systems, based on simple ferromagnetic metals, to mimic antiferromagnetic device physics. |
Monday, March 4, 2019 4:42PM - 4:54PM |
C67.00012: Implementation of a microwave readout for scanning superconducting quantum interference devices (SQUIDs) Rachel Resnick, Justin Oh, Farshad Foroughi, Jan-Michael Mol, Alexander B Jarjour, David Low, John Robert Kirtley, Hendrik Bluhm, Katja Nowack In scanning superconducting quantum interference device (SQUID) microscopy a SQUID is rastered close to the surface of a sample to obtain images of the sample’s magnetic properties. In this talk we will discuss a microwave readout for scanning SQUIDs that incorporate an on-chip capacitor as reported in [1]. In this case, the SQUID acts as a flux-dependent inductor, that forms an LC resonant circuit with the on-chip capacitor. The phase and amplitude of microwaves reflected by this circuit encode changes in magnetic flux. We will present our progress towards implementing this microwave readout and characterizing the SQUID noise performance at mK temperatures. The microwave readout holds the promise to both increase our flux sensitivity to below 100nPhi_0/sqrt(Hz) and our measurement bandwidth to several hundreds of MHz [1]. |
Monday, March 4, 2019 4:54PM - 5:06PM |
C67.00013: Optimizing a cryogen-free measurement system for measurement of single electron devices Leticia Damian, Justin K Perron Single electron devices (SEDs) are electronic devices capable of isolating individual electrons along a conducting path. This ability has many proposed applications including their use in metrology, and quantum information science. Recently our lab has installed a cryogen-free dilution refrigeration system for the purpose of investigating SEDs and their use in these applications. In this talk I will describe our efforts in optimizing the electrical measurement setup of this system. Our primary metric for optimization is electron temperature, a limiting factor in measurements of this type. |
Monday, March 4, 2019 5:06PM - 5:18PM |
C67.00014: Kinetic Separation of Hydrogen Isotopes in Metal-Organic Frameworks Katharine Rigdon, Naiyuan (James) Zhang, Stephen Fitzgerald Deuterium is a valuable hydrogen isotope with applications in NMR, nuclear power, and as a medical tracer. It constitutes less than 0.02% of naturally occurring hydrogen and is challenging to isolate. Current industrial separation techniques, which rely on tiny differences in the isotopes' chemical behavior, are expensive and energy intensive. Recently a new approach based on difference in the confined isotopes' zero-point energy has emerged. While these "quantum sieving" methods exhibit higher selectivity, many practical obstacles remain for them to replace the standard chemical approach. I will present data on a kinetics based separation within highly porous pellets of metal-organic frameworks (MOF). Mass spectroscopy with isotope mixtures shows breakthrough times that differ by more than three minutes. While these results are obtained at liquid nitrogen temperature, it is expected that planned experiments with the MOF known as Cu-MFU-4l should produce similar time differences at room temperature. |
Monday, March 4, 2019 5:18PM - 5:30PM |
C67.00015: Quantitative Imaging of Cytoskeletal Filaments of C17.2 Cells Jay Magers, Julia Hutsko, Sabrina Jedlicka, Swetha Chandrasekar, Slava V. Rotkin, Massooma Pirbhai, Lisa Schneider The ability of cells to resist deformation, to transport intercellular cargo and to change shape during movement depends on the cytoskeletal filaments. Recent work has demonstrated that internal and external stimuli can affect these filaments and thus cellular behavior. Therefore, it is important to understand how to quantitatively extract data about the network of filaments and their changes. This research focuses on the modeling of the cytoskeletal networks to create a catalogue of them. While many cell analysis programs already exist, most are complex to use and are designed to analyze multiple types of cells and situations with limited customization in the program’s analysis. Therefore, in order to obtain a more specialized analysis, different programing languages were explored in order to develop a custom analysis method. Several custom program were developed primarily utilizing the Python image analysis library OpenCV and MATLAB. This talk will explore the actin structures in C17.2 neural stem cells and compare the different programs’ methods and capability to segment individual cells then calculate their fluorescent density. |
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