Bulletin of the American Physical Society
2019 Annual Meeting of the APS Four Corners Section
Volume 64, Number 16
Friday–Saturday, October 11–12, 2019; Prescott, Arizona
Session L04: Condensed Matter Physics IV |
Hide Abstracts |
Chair: TC Shen, Utah State University Room: AC1 104 |
Saturday, October 12, 2019 11:00AM - 11:12AM |
L04.00001: Magnetic Behavior of Multilayered [Co/Pt] Thin Films Aaron Gentillon, Carson Richards, Luis Ortiz, Jeremy Metzner, David Montealegre, Andrew Westover, Karine Chesnel I will present a study of the behavior of magnetic domains in multilayered [Co/Pt] thin films. The basic thin film structure is an alternation of Cobalt layers of thickness X and 7 {\AA} Platinum layers. There are eight different thicknesses, (X$=$4,8,12,16,25,31,40,60 {\AA}). Using Atomic/Magnetic Force Microscopy, we estimated the density of magnetic domains at remanence after the application of a certain magnetic field perpendicular to the film. To study the domain density's dependence on the magnitude H$_{\mathrm{m}}$ of the applied field, we applied a series of magnetization loops to the samples via Vibrating Sample Magnetometer. Each sample was studied through an ascending and descending series of loops from 0 T up to 9 T and vice versa. Our results have shown in each sample that there is a value H* of H$_{\mathrm{m}}$ for which the domain density is maximized. We observed that X$=$31 {\AA} has a higher peak than the other thicknesses. The ascending and descending series seem to have their density peaks in approximately the same places, but the descending series generally have higher peaks. Also, we completed a pumping study in which H* is applied multiple times in a row to observe if the domain density would increase. We found that pumping H* didn't show any correlation to increasing the domain density. [Preview Abstract] |
Saturday, October 12, 2019 11:12AM - 11:24AM |
L04.00002: Magnetic phase competition in the XY pyrochlore Er$_{\mathrm{2}}$Sn$_{\mathrm{2}}$O$_{\mathrm{7}}$ Danielle Yahne, L. D. C. Jaubert, L. D. Sanjeewa, J. W. Kolis, D. Pereira, M. Enjalran, M. J. P. Gingras, K. A. Ross XY pyrochlores ([Yb/Er]$_{\mathrm{2}}$M$_{\mathrm{2}}$O$_{\mathrm{7}}$, where M is the non-magnetic site) have attracted interest due to their rich phase diagram. Er$_{\mathrm{2}}$Sn$_{\mathrm{2}}$O$_{\mathrm{7}}$ lies near a phase boundary in exchange parameter space, resulting in a competition between classically ordered phases. It undergoes a phase transition into a magnetically ordered ``Palmer-Chalker'' state at a lower temperature than Monte-Carlo simulations predict based on available estimates of the exchange interactions. The suppression of this transition temperature has been attributed to quantum fluctuations arising from the phase competition, but details of the energetics and resulting phase behavior were previously unknown. We report on magnetic field dependent specific heat measurements on Er$_{\mathrm{2}}$Sn$_{\mathrm{2}}$O$_{\mathrm{7}}$, as well as Monte-Carlo simulations and mean field theory calculations on the relevant model, which offer clear insights into the details of this phase competition. Above a threshold field value of 0.2 T, we find a reentrant phase diagram, which compares well qualitatively with classical Monte Carlo simulations. Differences between classical simulations and experiments at low field provide further evidence of strong quantum fluctuations in Er$_{\mathrm{2}}$Sn$_{\mathrm{2}}$O$_{\mathrm{7}}$, suggesting its proximity to a quantum disordered regime such as a quantum spin liquid. [Preview Abstract] |
Saturday, October 12, 2019 11:24AM - 11:36AM |
L04.00003: Spintronic Transport Device Using a Magnetic Skyrmion Lattice David King, Jinke Tang Magnetic skyrmions are a topologically protected state in certain magnetic systems. Their topological properties make skyrmion states stable and thus a possible basis for memory or energy storage spintronic devices. We present preliminary results for a transport device that uses a skyrmion lattice in the magnetic insulator Cu$_{2}$OSeO$_{3}$ as a precursor to an energy storage system. Data from the transport device are shown and these are used to test the underlying elasticity theory for the skyrmion lattice. [Preview Abstract] |
Saturday, October 12, 2019 11:36AM - 11:48AM |
L04.00004: Proposed Universal Deutsch Gate Circuitry Using GaAs/InAs Quantum Dots Paul Bailey, Jean-Francois Van Huele The Deutsch gate is a universal quantum logic gate, meaning that any quantum computing task can be completed using only a series of Deutsch gates. Although a proposal exists to build a Deutsch gate using Rydberg atoms [X-F Shi, Phys. Rev. Applied~\textbf{9}, 051001], to our knowledge no Deutsch gate has been experimentally realized. We propose to combine two GaAs/InAs quantum dots described by [Bouwmeester et al., Phys. Rev. Lett.~\textbf{104}, 160503] with photon polarization in a larger circuit comprised of linear optical elements to create a spin-spin-photon polarization three qubit Deutsch Gate. In this talk we display the circuit and discuss the intricacies of designing a universal gate. [Preview Abstract] |
Saturday, October 12, 2019 11:48AM - 12:00PM |
L04.00005: Plasmonic Color Printing in the Nineteenth-Century Paul Gieri, Andrea Schlather, Mike Robinson, Silvia Centeno, Alejandro Manjavacas Due to their ability to support plasmonic resonances, metallic nanoparticles are being exploited to develop novel color printing approaches. However, plasmonic color printing is not so ``new.'' Indeed, daguerreotypes, which are recognized as the first technology capable of capturing an image from a camera, are an example of plasmonic color printing. Daguerreotypes were first proposed in 1839 and saw widespread use for the next several decades. Although unknown at the time, the image on a daguerreotype is a result of plasmonic light scattering from a multitude of metallic nanoparticles on its surface. In this work we combine scientific expertise and daguerreotype artistry to unravel the plasmonic properties of these early photographs, providing important insight needed to develop preservation protocols for these priceless works, as well as to inform the development of future color printing technologies. [Preview Abstract] |
Saturday, October 12, 2019 12:00PM - 12:12PM |
L04.00006: Does $\beta-PbO_{2}$ Harbor Topological States? Sharad Mahatara, Boris Kiefer The electronic properties of $\beta-PbO_{2}$, have been controversial for over a century. Experiments find metallic behavior, attributed to its defect structure, to indirect semiconducting for stoichiometric samples, with a gap of 0.61 eV. Theory leads to similar ambiguities, and predicts this phase to be metallic (PBE, HSE06) or the opening of too small bandgap (HSE06). An area where this inconsistency is significant, is when a material property depends on the electronic structure in the vicinity of the Fermi energy, such as topological states. In our work, we use a self-consistent DFT+U approach and find stoichiometric $\beta-PbO_{2}$ to be an indirect semiconductor with a band gap of $\sim$ 0.8 eV, similar to experiment. The larger bandgap requires strains of $\sim 4\%$ to drive $\beta-PbO_{2}$ into a nodal line semimetallic state, which is not protected under the application of spin-orbit-coupling. These insights are also supported by our surface computations, that do not show any topologically protected states near the Fermi energy. Therefore, our results show that in contrast to previous computations $\beta-PbO_{2}$ is a topologically trivial material, consistent with experiment, an observation that can be attributed to the inaccurate optical properties in previous work. [Preview Abstract] |
Saturday, October 12, 2019 12:12PM - 12:24PM |
L04.00007: Frequentist Approach to Uncertainty Quantification of Interatomic Models in OpenKIM Database Yonatan Kurniawan, Mark Transtrum, Cody Petrie, Kinamo Williams Interatomic models (IMs) are used in molecular modeling to predict material properties of interest. The development of a single IM can take anywhere from several months to years and relies on expert intuition, and yet these potentials are usually only valid for a particular application of interest. Extending existing IMs to new applications is an active area of research. Quantifying the uncertainty of an IM can tell us how much we can trust the predictions it makes. I take a frequentist approach to uncertainty quantification. I calculate the profile likelihood of the parameters in the IM to identify regions of the parameter space that are statistically consistent with the data on which it is trained. I demonstrate this method on Lennard-Jones and Morse potentials fit to triclinic crystal configurations from the OpenKIM database. Results indicate that these models are "sloppy" in some of their parameters, i.e., likelihood surfaces have long, narrow canyons and broad, flat plateaus. I discuss implications of sloppiness for molecular modeling and potential extensions to more complex potentials. [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