Bulletin of the American Physical Society
2017 Annual Meeting of the APS Mid-Atlantic Section
Volume 62, Number 19
Friday–Sunday, November 3–5, 2017; Newark, New Jersey
Session E3: CMP-QM: Low Dimensional Structures |
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Chair: Alexander Efros, Naval Research Laboratory Room: 215, Campus Center, NJIT |
Saturday, November 4, 2017 10:00AM - 10:36AM |
E3.00001: Electronic and Optical Properties of Lead Halide Perovskite Nanocrystals Invited Speaker: Alexander Efros The growing attention to perovskite nanocrystals is connected with their unusual and potentially useful electronic and optical properties. I will discuss the bulk energy band structure of CsPbX$_{\mathrm{3}}$ (X $=$ I, Cl, and Br) perovskites and show that all of them have the band edge at R-point of the Brillouin zone. To describe electronic and optical properties of perovskite nanocrystals we have derived the four band effective mass Hamiltonian, which describes the electronic properties of electron and holes near the band edge. Using this Hamiltonian we calculate the lowest quantum confined levels of electrons and holes and the spectra of the allowed optical transitions. The calculations takes into account the cubic shape of the perovskite nanocrystals, that results into inhomogeneous electric field of emitted and absorb photons. The symmetry of the ground exciton state has been analyzed and the radiative decay time has been calculated. The results of our theoretical calculations are in a good agreement with available experimental data. [Preview Abstract] |
Saturday, November 4, 2017 10:36AM - 11:12AM |
E3.00002: Anomalous transport properties of SrTiO3 accumulation layers. Invited Speaker: Boris Shklovskii We study the low temperature conductivity of the electron accumulation layer induced by the very strong electric field at the surface of SrTiO3 sample. Due to the strongly nonlinear lattice dielectric response, the three-dimensional density of electrons in such a layer decays with the distance from the surface very slowly. We show that when the mobility is limited by the surface scattering the contribution of such a tail to the conductivity diverges at large distances because of growing time electrons need to reach the surface. We explore truncation of this divergence by the finite sample width, by the bulk scattering rate, by the back gate voltage, or by the crossover to the bulk linear dielectric response. As a result we arrive at the anomalously large mobility, which depends not only on the rate of the surface scattering, but also on the physics of truncation. Similar anomalous behavior is found for the Hall factor, the magneto-resistance, and the thermo-power. [Preview Abstract] |
Saturday, November 4, 2017 11:12AM - 11:24AM |
E3.00003: Evolution of Domain Structures and Topological Defects in Hexagonal Manganites Fei Xue, Xueyun Wang, Sang-Wook Cheong, Long-Qing Chen Multiferroic hexagonal (h-) REMnO3 (RE, rare earths) have attracted significant attentions due to their intriguing physics and potential applications. The h-REMnO3 possess six domain variants, which can cycle around vortex and antivortex cores, so called “topological defects”. The evolution of the domain structures and topological defects in h-REMnO3 is predicted using phase-field simulations in both two-dimensional (2D) and 3D cases. The temporal evolution of domain and vortex structures allows us to fully explore the mesoscale mechanisms for the vortex-antivortex annihilation, evolution of vortex line loops, and domain wall motion with and without external electric fields. It is demonstrated that the vortex motion and vortex-antivortex annihilation control the scaling dynamics during the domain coarsening process, while vortex line loops show three types of topological changes, i.e., shrinking, coalescence, and splitting. It is also shown that an in-plane external strain can unfold the vortex domains into incommensurate domains. [Preview Abstract] |
Saturday, November 4, 2017 11:24AM - 12:00PM |
E3.00004: THz- and infrared ellipsometry studies of plasmonic modes in complex oxide heterostructures Invited Speaker: Christian Bernhard I will present THz- and infrared ellipsometry studies of complex oxide heterostructures with mobile charge carriers that are spatially confined. The first example concerns the two-dimensional electron gas in LaAlO$_{\mathrm{3}}$/SrTiO$_{\mathrm{3}}$ and related materials for which the sheet carrier density, the depth profile and the mobility of the charge carriers are obtained from the analysis of a so-called Berreman-mode. The second example is about Pr$_{\mathrm{0.5}}$La$_{\mathrm{0.2}}$Ca$_{\mathrm{0.3}}$MnO$_{\mathrm{3}}$/YBa$_{\mathrm{2}}$Cu$_{\mathrm{3}}$O$_{\mathrm{7}}$/Pr$_{\mathrm{0.5}}$La$_{\mathrm{0.2}}$Ca$_{\mathrm{0.3}}$MnO$_{\mathrm{3}}$ (PYP) trilayers for which we recently discovered a very unusual kind of insulator-to-superconductor transition as a function of an applied magnetic field. Our THz-ellipsometry and magneto-transport data reveal that the insulator-like response at zero magnetic field arises in fact from a granular superconducting state with very efficient domain boundaries that completely block the superconducting phase coherence. [Preview Abstract] |
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