Bulletin of the American Physical Society
Four Corners Section 2022 Meeting
Volume 67, Number 14
Friday–Saturday, October 14–15, 2022; Albuquerque, New Mexico
Session E03: Condensed Matter Physics II |
Hide Abstracts |
Chair: Victor Acosta, University of New Mexico Room: UNM PAIS 2540 |
Friday, October 14, 2022 2:30PM - 2:54PM |
E03.00001: Shaping the Energy Landscape: Advances in Spin Hall Oscillators Invited Speaker: Eric A Montoya Creating new pathways to achieve faster and more energy efficient ways to store, process, and transfer information is both a challenging and exciting undertaking. Spin Hall oscillators (SHOs) are nanoscale sources of electrically tunable microwave radiation that operate far from equilibrium and whose dynamics are inherently nonlinear. These properties make SHOs attractive for applications such as neuromorphic computing, microwave assisted magnetic recording, and wireless communication. In this talk, we will present how we can shape the magnetic energy landscape of nanowire based SHOs to enhance their performance. We will present a new type of SHO engineered to have easy-magnetic-plane oriented normal to the film plane, enabling large-amplitude spin Hall driven dynamics. While many ferromagnets exhibit natural easy-plane anisotropy in the film plane, the spin Hall current in a heavy metal/ferromagnet bilayer is polarized in this plane and thus cannot drive large-amplitude dynamics. We demonstrate that an artificial easy-plane anisotropy can be achieved by tuning shape and perpendicular magnetic anisotropies in a simple-to-fabricate SHO nanowire, leading to significantly enhanced microwave emission. |
Friday, October 14, 2022 2:54PM - 3:06PM |
E03.00002: Strain-Induced Ferromagnetism in Twisted-Bilayer Graphene Jasper Bradford, Chuankun Liu, Vikram V Deshpande, Dinesh K Yadav Twisted bilayer graphene has recently proved to be an interesting two-dimensional system. Because the twisting between two graphene layers creates unit moiré superlattice cells on the order of the magnetic length for a perpendicular magnetic field of several tesla, the Hofstadter butterfly spectrum can be observed in the laboratory. When the twist angle is at 1.1 degrees, also known as the 'magic angle', the high density of states causes it to exhibit superconductivity, correlated insulating states, ferromagnetism and topological behavior, among others. This wide range of phenomena has raised the question: why do device properties vary so much from one device to the next? One idea is that the fabrication process introduces strain into the lattice, and the different strain experienced by different devices causes disparity in the results. To test this, we isotropically strained magic angle and near-magic angle TBLG devices to study how the observed phenomena changed with strain. We observed a device that behaved like a conductor in the absence of strain become ferromagnetic upon the application of strain. While this result suggests that strain does play an important role, more experiments are needed to fully understand the effects of strain. |
Friday, October 14, 2022 3:06PM - 3:18PM |
E03.00003: Time-Correlation of Magnetite Nanoparticle to determine dynamics of fluctuations through superparamagnetic transition Corey Hawkins, Karine Chesnel, Daniel McPherson, Johnathon M Rackham Magnetic nanoparticles have possible uses in many fields, including industry and medicine. To help facilitate their use and ensure their stability in time, we are investigating the magnetic properties of Fe3O4 (magnetite) nanoparticles, specifically the dynamics of magnetic fluctuations throughout the superparamagnetic transition, below which the nanoparticle spins are magnetically frozen. We accomplish this by cross-correlating x-ray scattering speckle patterns collected at successive times and at various temperatures. The data was collected using synchrotron radiation. Here I will show how we address instability issues in data collection. By developing a homemade cross-correlation process, based on Fourier transforms, and by adjusting the integration area of the correlation signal, and tracking spatial shifts, we show that we can recover the physical superparamagnetic transition signal, even when hidden in instrumental noise. |
Friday, October 14, 2022 3:18PM - 3:30PM |
E03.00004: Magnetic Characterization and Blocking Temperature of Fe3O4 NanoparticlesBryce Iverson, Karine ChesnelDepartment of Physics and Astronomy, Brigham Young University, Utah, USA Bryce J Iverson, Karine Chesnel Magnetite (Fe3O4) nanoparticles (NPs) are becoming an increasingly useful tool in many applications, from nanotechnologies to the medical field. However, one of the most interesting characteristics of these NPs, their superparamagnetic behavior, requires more data and research, in order to establish the blocking temperature below which the nanoparticles are magnetically blocked. We are investigating how the different sizes of clusters of Fe3O4 NPs change their respective blocking temperature. In order to research this, we are using Vibrating Sample Magnetometry to measure the magnetic moment of the nanoparticles while field cooling and observing the superparamagnetic transition. From there we use a couple different analytical methods to find proper estimates of the blocking temperatures, which we then use to find a relationship between the blocking temperature and size of the nanoparticles. |
Friday, October 14, 2022 3:30PM - 3:42PM |
E03.00005: Magnetic impurities turn colloidal quantum dots into emitters of free electrons Clément Livache, Whi-Dong Kim, Ho Jin, Victor I Klimov Colloidal Quantum Dots (CQDs) are solution-based nanoscale semiconductors with a wide range of applications in lighting, displays, solar energy harvesting and optoelectronic devices. Under optical excitation, those objects host excitons (electron-hole pairs). The dynamics evolution of those excitons is studied in our lab using ultrafast spectroscopy techniques. |
Friday, October 14, 2022 3:42PM - 3:54PM |
E03.00006: Response of Thin Metal Nanodisks to Near- and Far-Field Excitation Lauren Zundel, Paul Gieri, Stephen Sanders, Alejandro Manjavacas Metallic nanostructures support surface plasmons, collective oscillations of their conduction electrons, making them useful for a wide range of applications, from ultrasensitive optical sensing to efficient solar energy harvesting. Surface plasmons also strongly confine and enhance the electromagnetic fields in their vicinity. In recent years, this has motivated significant interest in the plasmons supported by thin metallic nanostructures, for which the degree of confinement and enhancement can be much higher than conventional ones. Here, we investigate how the response of metallic nanodisks to excitation by near- and far-field sources varies with their thickness. In the latter case, which corresponds to a scenario in which the separation between the nanostructure and excitation source is much larger than the wavelength, we find that the response of the nanodisks increases with their thickness. On the other hand, in the opposite limit, the response of the nanodisks decreases with the thickness, a result that we attribute to a near-field source coupling more efficiently with thinner nanodisks. The results of our work provide fundamental insight into the plasmonic properties of thin metallic nanostructures and thus pave the way toward the development of novel applications. |
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