Bulletin of the American Physical Society
2021 Annual Meeting of the APS Four Corners Section
Volume 66, Number 11
Friday–Saturday, October 8–9, 2021; Virtual; Mountain Daylight Time
Session B02: Functionalities of Materials I |
Hide Abstracts |
Chair: Minhyea Lee, University of Colorado Boulder |
Friday, October 8, 2021 10:30AM - 10:54AM |
B02.00001: Surprises in Heat Transport in Sub-100 nm thin films and nanostructures: From Breaking the "Law” to Putting a New Spin on Metals Invited Speaker: Barry Zink Nanoscale engineering of materials for heat management or energy harvesting brings both tremendous promise and serious fundamental measurement challenges. For materials ranging from graphene to carbon nanotube hybrids to nanomagnetic systems or films, samples with one or more dimensions on the sub-100 nm scale are always difficult to thermally characterize. Our approach to these measurements uses micro- and nanomachined thermal isolation platforms that allow exceptional control over thermal gradients and unambiguous alignment of this gradient in the plane of a thin film or nanoscale sample. Micromachined electrical leads enable thermal conductivity, electrical conductivity, and Seebeck effect measurements all on the exact same sample. This allows a particularly powerful probe of the fundamental physics of thermal and thermoelectric transport, which has often revealed surprising behavior. In this talk I will overview several recent results including investigations of increased thermoelectric potential in semiconducting carbon nanotube systems, reduced thermal conductivity in thin gold films where a violation of the Wiedmann-Franz ”Law” occurs, and the first indication of spin waves contributing to heat flow in a metallic ferromagnet. [Preview Abstract] |
Friday, October 8, 2021 10:54AM - 11:18AM |
B02.00002: A bond-selective view of electron-phonon coupling Invited Speaker: Samuel Teitelbaum X-ray free electron lasers (XFELs) hold promise for revealing the properties of materials on their fundamental length and time scales near and far from equilibrium. Their combination of high flux, short pulse duration x-ray pulses makes them ideally suited for time-domain x-ray scattering studies of phonons. We can reconstruct nonequilbrium interatomic forces using optical pump, x-ray probe studies. The forces are obtained by a constrained least-squares fit of a pairwise interatomic force model to the excited-state phonon dispersion relation. This bond-selective approach to measuring electron-phonon coupling is relevant to a broad range of photoinduced phase transitions and transient light-driven states. Here, we show how this approach reveals the role of short-range forces in the bonding prototypical Peierls distorted material -- bismuth, and long-range forces in the gold-standard thermoelectric bismuth telluride. [Preview Abstract] |
Friday, October 8, 2021 11:18AM - 11:30AM |
B02.00003: Physical and Thermoelectric Properties of 2-D B$_4$C Nanosheets Adway Gupta, Tathagata Biswas, Arunima Singh Boron carbide has been well studied both theoretically and experimentally due to its exceptional hardness and use as a high temperature thermoelectric. However, the properties of its two-dimensional nanosheets have not been well established. Here, using van der Waals corrected density-functional theory (DFT) simulations, we show that the bulk B$_4$C can be cleaved along different directions to form B$_4$C nanofilms that have low formation energies. We find the dependence of the formation energies on the cleavage planes and surface terminations to be minimal. We also perform a density of states analysis on the bulk using the G$_0$W$_0$ method for a more accurate bandgap. Although the density of states of the bulk B$_4$C reveal that it is a semiconductor with a bandgap of 2.3 eV, the B$_4$C films are predominantly metallic. We attribute this metallic behaviour to the redistribution of the charges between the B-C bonds at the surface of the films. We find that the Seebeck coefficients of the the B$_4$C films remain comparable to those of the bulk at varying temperatures. Our work shows that B$_4$C 2-D films can be synthesised fairly easily along multiple directions, while maintaining near identical thermoelectric properties as that of the bulk. [Preview Abstract] |
Friday, October 8, 2021 11:30AM - 11:42AM |
B02.00004: Fabricating Diamond-like Amorphous Carbon Carson McLaughlin Using a magnetically confined hot hollow cathode, we perform plasma-enhanced chemical vapor deposition (PE-CVD). Hydrocarbon gas is decomposed under a diluent gas to deposit hydrogenated amorphous carbon onto a sample holder. During the fabrication of the hydrogenated amorphous carbon, the electric potential, electron temperature, and electron density of the plasma are measured with a Langmuir probe. Raman spectroscopy is used to determine the structural and electronic characterization of the final hydrogenated amorphous carbon solid. [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