Bulletin of the American Physical Society
Annual Meeting of the APS Four Corners Section
Volume 60, Number 11
Friday–Saturday, October 16–17, 2015; Tempe, Arizona
Session K3: Condensed Matter Physics VII |
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Chair: Dmitry Yarotski, Los Alamos National Laboratory Room: PSA103 |
Saturday, October 17, 2015 1:12PM - 1:36PM |
K3.00001: Intense light-matter interaction: How electron spin can influence strong-field ionization Invited Speaker: Scott Sayres Advancements in laser technology continually push the interaction of light and matter to new limits, reaching unexplored frontiers where new science is emerging. Although light cannot directly interact with electron spin, I will present our recent experiments demonstrating that spin can play a profound role on ionization driven by strong-field laser pulses. Tabletop extreme ultraviolet (XUV) transient absorption spectroscopy is used to measure the angular distributions of singly and doubly tunnel-ionized xenon atomic states via 4d core to 5p valence shell transitions between 55 and 60 eV. These orbital alignment measurements are combined with theory to reveal new details about electron correlation (electron-electron interaction) during atomic strong-field double ionization that are fundamentally important for understanding light-matter interaction. [S. G. Sayres, E. R. Hosler, and S. R. Leone, J. Phys. Chem. A 118, 8614 (2014).] [Preview Abstract] |
Saturday, October 17, 2015 1:36PM - 1:48PM |
K3.00002: Zero Bias Anomaly in Point Contact Andreev Reflection Spectroscopy$\backslash $fs20 Jessica Gifford, Gejian Zhao, Bochao Li, Ji Zhang, Dongrin Kim, Tingyong Chen h $-abstract-$\backslash $pard Zero bias anomaly (ZBA) in point contact Andreev reflection spectroscopy (PCAR) has been utilized as a characteristic feature to reveal many novel physics including superconductivity with nodes, topological superconductivity, Majorana states, and two band superconductivity. However, complexities at a superconductor/normal metal interface often causes nonessential ZBA-like features, which may be readily mistaken as ZBA. In this work, we show that an intrinsic ZBA in a $d$-wave superconductor, which is due to the Andreev reflection, can be suppressed by a spin-polarized current while a nonessential ZBA cannot be affected by a spin-polarized or half-metallic current and can be induced in conventional superconductors, therefore it is extrinsic to the superconductor. By systematically varying the contact resistance, we find that the non-essential ZBA depends on the contact resistance and evolves from properties of a specific interface while the intrinsic ZBA is independent of point contacts. This work demonstrates that it is crucial to administer PCAR correctly in the proper region to obtain the intrinsic properties of the materials in question to reveal new physics. $\backslash $pard-/abstract-$\backslash $\tex [Preview Abstract] |
Saturday, October 17, 2015 1:48PM - 2:00PM |
K3.00003: Intense light-matter interaction: How electron spin can influence strong-field ionization Scott Sayres, Erik Hosler, Stephen Leone Advancements in laser technology continually push the interaction of light and matter to new limits, reaching unexplored frontiers where new science is emerging. Although light cannot directly interact with electron spin, I will present our recent experiments demonstrating that spin can play a profound role on ionization driven by strong-field laser pulses. Tabletop extreme ultraviolet (XUV) transient absorption spectroscopy is used to measure the angular distributions of singly and doubly tunnel-ionized xenon atomic states via 4d core to 5p valence shell transitions between 55 and 60 eV. These orbital alignment measurements are combined with theory to reveal new details about electron correlation (electron-electron interaction) during atomic strong-field double ionization that are fundamentally important for understanding light-matter interaction. [S. G. Sayres, E. R. Hosler, and S. R. Leone, J. Phys. Chem. A 118, 8614 (2014).] [Preview Abstract] |
Saturday, October 17, 2015 2:00PM - 2:12PM |
K3.00004: Observation of \textit{p}-wave superconductivity in epitaxial Bi/Ni bilayers Gejian Zhao, Xinxin Gong, Jessica Gifford, Hexin Zhou, Xiaofeng Jin, C. L. Chien, Tingyong Chen In a singlet superconductor, the two electrons within a Cooper pair have opposite spins whereas the two electrons have the same spin orientation in a triplet superconductor. Most superconductors to date are singlet superconductors with an $s$-wave (e.g., Pb, Nb) isotropic gap, except the high $T_{C}$ cuprates with a $d$-wave gap with nodes. However, $p$-wave triplet superconductivity, although theoretically expected, was rarely observed. He$^{\mathrm{3}}$ is the only triplet superfluid in nature, and Sr$_{\mathrm{2}}$RuO$_{\mathrm{4}}$ has been suspected to be a triplet superconductor. We report the observation of $p$-wave triplet superconductivity in epitaxial Bi/Ni bilayers with $T_{C}$ up to 4 K in multiple thickness ranges. Using ballistic injection of unpolarized and especially highly spin-polarized electrons with energies within the superconducting gap, Andreev reflection spectroscopy directly accesses the pairing symmetry within the superconducting gap. We obtain conclusive evidence of $p$-wave superconductivity. [Preview Abstract] |
Saturday, October 17, 2015 2:12PM - 2:24PM |
K3.00005: Fabrication of Dye Sensitized Solar Cells Using Fe-, Mn- and Co-oxyhydroxide nanocrystals in ferritin as the dye Alessandro Perego This project is based on the study published by the Colton and Watt group at BYU in the journal \underline {Nanotechnology}$. $In this paper, it has been theorized that a solar cell fabricated with different nanocrystals, synthesized inside the protein ferritin, is capable of harvesting different wavelengths of the solar spectrum. This therefore, makes it possible to increase the efficiency of the cell up to 44.9{\%}. This presentation will show the fabrication and characterization of three dye-sensitized solar cells using iron, manganese, and cobalt oxyhydroxide nanocrystals within ferritin as the dye. The open current voltage obtainable from these three nanocrystals was respectively 307 mV, 435 mV and 552 mV. Because those measurements exceeded the voltage of our anthocyanin based dye sensitized solar cells solar cell control (182mV), we believe that ferritin possesses the necessary properties that can be used for the development of future third generation solar cells. [Preview Abstract] |
Saturday, October 17, 2015 2:24PM - 2:36PM |
K3.00006: Strong Coupling between ZnO Excitons and Localized Surface Plasmons of Silver Nanoparticles Studied by STEM-EELS Jiake Wei, Jingyue Liu We investigated the strong coupling between the excitons of ZnO nanowires (NWs) and the localized surface plasmons (LSPs) of individual Ag nanoparticles (NPs) by monochromated electron energy loss spectroscopy (EELS) in an aberration-corrected scanning transmission electron microscopy (STEM) instrument. The EELS results confirmed that the hybridization of the ZnO excitons with the LSPs of the Ag NPs created two plexcitons: the lower branch plexcitons (LPs) with a symmetrical dipole distribution and the upper branch plexcitons (UPs) with an anti-symmetrical dipole distribution. The spatial maps of the LP and UP excitations reveal the nature of the LSP-exciton interactions. When the size of the Ag NP decreases the peak energies of the LPs and UPs show a blueshift, and an anticrossing behavior at the ZnO exciton energy was observed. The coupled oscillator model can be used to understand the dispersion curve of the plexcitons and a Rabi splitting energy of \textasciitilde 170 meV was deduced. The high spatial resolution monochromated STEM-EELS approach demonstrated in this work is general and can be extended to study the various coupling interactions of a plethora of metal-semiconductor nanocomposite systems. [Preview Abstract] |
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