Bulletin of the American Physical Society
2021 Virtual Conference for Undergraduate Women in Physics
Friday–Sunday, January 22–24, 2021; Virtual
Session U03: Condensed MatterInteractive Live
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Chair: Valentin Taufour, University of California, Davis |
Sunday, January 24, 2021 12:00PM - 12:10PM |
U03.00001: Machine Learning Correlates Charge Density Wave with the Local Gap in Cuprate Superconductors Kaylie Hausknecht, Tatiana Webb, Michael Boyer, Yi Yin, Takeshi Kondo, Tsunehiro Takeuchi, Hiroshi Ikuta, Eric Hudson, Jennifer Hoffman With the advent of atomic resolution imaging techniques comes the challenge of disentangling the intrinsic electronic properties of materials from their stochastic atomic-scale disorder. In the past decade, machine learning (ML) image analysis techniques have rapidly evolved, while their applications in physics are just emerging. Here, we use ML to test local correlation hypotheses between spatially resolved measurements of disordered materials to overcome the limitations of standard Fourier analysis techniques. By training on a simulated density wave (DW) dataset, we develop a convolutional neural network (CNN) to uncover the doping-dependence of the DW in the cuprate superconductor (Pb,Bi)$_{2}$(Sr,La)$_{2}$CuO$_{6+δ}$ (Bi-2201) imaged via scanning tunneling microscopy. In Bi-based cuprates, the electronic inhomogeneity, caused by local variations in doping, limits the precision with which the DW wavevector can be measured. Our ML algorithm overcomes this limitation and allows clear differentiation between commensurate and incommensurate DW instabilities with physically distinct mechanisms. More broadly, our work lays the foundation for a ML approach to quantify intrinsic periodic order and correlations in datasets where these trends are masked by disorder. [Preview Abstract] |
Sunday, January 24, 2021 12:10PM - 12:20PM |
U03.00002: Controllability of Granular Packings Samantha Simon, Erin Teich, Danielle Bassett Granular packings are disordered, athermal systems common in our everyday lives. Following perturbation, their evolution depends on the force chain network, a mesoscale stress-distributing structure. Yet, it is unknown how force chain networks change under applied stress. Here we tackle this knowledge gap using network control theory (NCT). NCT is a branch of systems engineering and statistical physics developed to understand and control the activity of networked systems in technology, robotics, and many other structures. It considers the network of connectivity between units, modeling the nature of the system’s dynamics as being constrained by that connectivity. A powerful technique revolutionizing other fields, NCT is a promising approach to study force chain networks both conceptually and mathematically. We use NCT to estimate the control energy needed for a packing to transition between contact states. Our preliminary results indicate that control energy increases with system size and jamming, providing physical intuition for characterizing force chain architecture evolution. More broadly, our findings can inform design principles by determining how changing the physical features of a granular packing impacts the system's force chain network architecture and stress behavior. [Preview Abstract] |
Sunday, January 24, 2021 12:20PM - 12:30PM |
U03.00003: Investigating the Effects of Aluminum Additions in $Cu_{55-x}Zr_{45}Al_{x}$ Metallic Liquids Leah Zimmer, Sarah Bertrand, Peadar McGrath, Nicholas Mauro Metallic glasses, their applications and structure are topics of interest within the condensed matter community. In this work, systematic additions of aluminum in the poor bulk glass forming alloy $Cu_{55-x} Zr_{45}Al_{x}$ (x = 0-10) provide the means to track structural evolution with compositional changes. In all compositions studied, a crossover temperature $T_{S}$ is observed. This work provides insight into the viability of the metric $T_{S}$ as a fundamental indicator of glass forming ability since the value of $T_{S}$ may change as the glass forming ability changes. [Preview Abstract] |
Sunday, January 24, 2021 12:30PM - 12:40PM |
U03.00004: Investigating Spin Transport in Magnetic Oxide Systems with Ferromagnetic Resonance Yasemin Ozbek, Xuanyi Zhang, Divine Kumah, Dali Sun Conventional electronics that use the motion of electrons (charge current) to power devices and store memory have shortcomings, one of which is the loss of energy through the dispersion of heat generated by electron collisions. The field of spintronics has developed to reduce energy losses due to charge currents by storing and transmitting information using the spin of electrons. Hence, understanding spin transport and developing new spintronic materials is of great scientific and technological interest. In this study, we investigate the progression of spin waves in a novel complex oxide material. To do this, we utilize ferromagnetic resonance (FMR) to measure the properties of the spin current, which include the FMR peak-to-peak width and Gilbert damping parameter, which provide information on the sample's anisotropy and spin current damping respectively. We were successful in finding temperature dependence in our sample's damping parameter and effective magnetization. This study will broaden the current knowledge of spin transport in magnetic oxides by expanding the list applicable materials. [Preview Abstract] |
Sunday, January 24, 2021 12:40PM - 12:50PM |
U03.00005: Linking the dynamics of molecular prime knots to topological and local structural properties Hyo Jung Park, Lakshminarayanan Mahadevan, Anna Lappala Molecular knots (MKs) are structures entangled into the form of knots at a molecular level. Since the synthesis of the first artificial knot in 1989, various topologies of synthetic MKs have been realized, revealing their potential applications in biomedicine and nanotechnology. MKs have shown to perform specific functions based on their dynamic behaviors. Some protein-based knots, for example, can alternate between entangled and loose states and thus act as molecular machines that trap and release other molecules as desired. In defining their dynamics, the topology of MKs is known to play an important role, as knotting reduces degrees of freedom of molecular strands. However, understanding of what specific structural factors give rise to or allow certain types of dynamics is lacking. To understand these relationships, we build a methodology for studying knot dynamics in terms of topological and local structural properties. Specifically, we explore the dynamics of prime knots---knots that cannot be decomposed into two non-trivial knots---using Molecular Dynamics simulations and relate their principal motions to knot complexity, linking numbers, curvature, and torsion. We also investigate and compare the dynamics of symmetric and asymmetric prime knots. [Preview Abstract] |
Sunday, January 24, 2021 12:50PM - 1:00PM |
U03.00006: High Hydrostatic Pressure (0.5-2.5 GPa) Synthesis of Rare-Earth Nickel Oxides RNiO3 (R$=$La1-xYx) Sara Irvine, Holland Fielding, Quinn D.B Timmers, Gregorio Ponti, John T Markert h $pard$\backslash $pard-abstract-$\backslash $pardWe are interested in the rare-earth nickel oxides and investigating their electronic properties by using a hot press synthesis. Materials are first prepared by an ambient solid-state reaction (950\textdegree C), creating mixed-phase RNiOx materials. A hot piston-cylinder press, which can range from 5-25kbar at high temperatures (950C-1000C), is then used to search for new phases using either an oxidizer (KClO4) or pure, as it is naturally reducing [1][2]. We are studying nickelate phases, specifically RNiO3 (R$=$La1-xNdx), for the metal-insulator transition. We are also looking into how the size of the rare-earth metal could affect when this transition occurs. Currently, we are still working to get a pure phase sample, but have recently seen some success.$\backslash $[1]Luke G. Marshall, Ph. D. Thesis, The University of Texas at Austin, pp. 80--104 (2003).2] G. D\'{e}mazeau et al., J. Solid State Chem. 3, 582 (1971)-/abstract-$\backslash $pard$\ [Preview Abstract] |
Sunday, January 24, 2021 1:00PM - 1:10PM |
U03.00007: Exfoliation and Characterization of Ultrathin Graphite ilana Albert Ultrathin materials are well suited for application in thin and flexible electronics. In the Kealhofer lab at Williams College, we are developing a pump-probe experiment to examine phonon-phonon interactions in ultrathin materials such as few-layer graphene. This talk focuses on the techniques we use to exfoliate and characterize our samples. We micromechanically exfoliate the sample in order to produce graphene. To determine the thickness of these samples we use a combination of optical microscopy, atomic force microscopy, and a MATLAB script that uses Fresnel's equations. During our sample preparation process we transfer the sample from sticky tape to polydimethyl siloxane (PDMS) gel and then from the PDMS gel to a transmission electron microscope support that will be placed in the vacuum chamber for the experiment. The Kealhofer lab ultimately hopes to refine the sample preparation process in order to create a flake of graphene fit for use in the experiment. [Preview Abstract] |
Sunday, January 24, 2021 1:10PM - 1:20PM |
U03.00008: Fabrication of a space-charge-induced carrier guiding semiconductor device Ayesha Lakra Space-charge potentials are a crucial element in the understanding of charge transport in a semiconductor device. To understand the space-charge-induced carrier guiding, my group devised an experiment to visualize the dynamics of space-charge formation in a diamond with nitrogen vacancies (NV). My main contribution was the fabrication of a semiconductor device where I patterned two electrodes on a type 1b synthetic diamond. The fabrication process consisted of e-beam deposition and a lift-off UV photolithography. The device was connected to a high voltage power supply and the NV charge was excited by green and orange laser pulses which generated electrical fields. This semiconductor device will be useful for the group's overall aim of guiding space-charge carriers. [Preview Abstract] |
Sunday, January 24, 2021 1:20PM - 1:30PM |
U03.00009: Digital Quantum Simulation of Heisenberg Model Dynamics Britta Manifold, Cheng-Chien Chen Recent advancements in universal quantum computer technologies have raised the possibility of leveraging the so-called ”quantum advantage” to approach classically intractable problems. For simulations of quantum many-body systems,there is great potential to meet this goal in the near future. Here, we focus on small clusters of interacting spins and perform time evolution calculations in the quantum circuit paradigm using IBM’s superconducting qubit platform. We compare and analyze the noisy and exact dynamics of magnetization,n-point correlation functions, and dynamical spin structure factors. We repeat these circuits under various magnetic and spatial regimes. We also explore current practical error mitigation methods for more efficient time evolution. [Preview Abstract] |
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