Bulletin of the American Physical Society
2015 Annual Spring Meeting of the APS Ohio-Region Section
Volume 60, Number 3
Friday–Saturday, March 27–28, 2015; Kent, Ohio
Session E5: Condensed Matter II |
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Chair: Bjorn Lussem, Kent State University Room: KSU Student Center 317 |
Saturday, March 28, 2015 10:10AM - 10:25AM |
E5.00001: Dynamic coexistence of competing orders in multicomponent superconductors Maxim Dzero We study the nonequilibrium dynamics of an electronic model of competition between the spin-density wave and unconventional superconductivity in the context of iron-pnictides. Focusing on the collisionless regime we find that magnetic and superconducting order parameters may coexist dynamically after the quench even though the equilibrium state has only one order parameter. We consider different initial conditions concomitant with the phase diagram and in a certain regime identify new oscillatory amplitude modes with incommensurate frequencies for magnetic and superconducting responses. At the technical level we solve equations of motion for the electronic Green's functions and self-consistency conditions by reducing the problem to a closed set of Bloch equations in the pseudospin representation. [Preview Abstract] |
Saturday, March 28, 2015 10:25AM - 10:40AM |
E5.00002: Optical Investigations on Bare and Organic-Plasmonic coated GaAs-AlGaAs Core-Shell Nanowires Masoud Kaveh-Baghbadorani, Qian Gao, Chennupati Jagadish, Gerd Duscher, Hans-Peter Wagner We investigate the exciton emission from uncoated and gold/aluminum quinoline (Alq3) coated GaAs-AlGaAs core-shell nanowires (NW) by temperature- and intensity-dependent photoluminescence (PL). The vertically aligned 100 nm diameter zincblende NWs were grown on GaAs substrate using the Au catalyzed vapor-liquid-solid method. Au/Alq3 coated NW heterostructures were fabricated by organic molecular beam deposition. Intensity-dependent PL spectra show strong and weak emission bands at 1.515 and 1.47 eV at 15 K, which are attributed to the exciton transition and tentatively to an impurity related luminescence, respectively. Plasmonic NWs with an Au coating of nominal 10 nm thickness but without Alq3 spacer layer reveal a significant reduction of the PL intensity for both emission bands compared with the uncoated NW sample. The PL quenching is mainly attributed to an energy-transfer from free excitons in the NWs to plasmon oscillations in the deposited Au film. The plasmonic Au/Alq3 NW samples with same nominal Au layer thickness and Alq3 spacer layer thicknesses of 5 and 10 nm, respectively, reveal PL intensities which are noticeably stronger as in the Au coated NWs without Alq3 layer. The PL yield rises with increasing Alq3 spacer thickness. [Preview Abstract] |
Saturday, March 28, 2015 10:40AM - 10:55AM |
E5.00003: New sources for chemical vapor transport growth of zinc oxide nanowires Cody Wright, Marian Tzolov Zinc Oxide (ZnO) nanowires have attracted scientific interest due to their optical and piezoelectric properties. Chemical vapor transport is a simple and effective growth method. We have shown previously that the nature of the chemical reactions excludes carbon from incorporating the in the nanowires and the presence of carbon monoxide can modify the growth significantly. Building on these findings, we have developed new sources modifying the presence of carbon monoxide during the growth. We will present our findings of the source consumption and the morphology of the formed zinc oxide nanowires. These results are the base of our model for the processes within the source and in the growth zone. We are showing that the formation of thin, high aspect ratio nanowires is promoted by the presence of carbon monoxide during the growth. We will present evidence for the significance of the reactions in the gas mixture on the nanowire formation. [Preview Abstract] |
Saturday, March 28, 2015 10:55AM - 11:10AM |
E5.00004: Effect of Time and Temperature on Growth of PbSe Nanorods Shreedhar Kandel, Zhoufeng Jiang, Shailendra Chiluwal, Liangfeng Sun Colloidal nanostructured materials are promising for applications in optoelectronic devices. Beyond size-tuning as in quantum dots, shape-tuning of the material at the nanometer scale also results in novel optical and electronic properties. The applications demand high quality and structure-well-controlled materials, which is still underdeveloped. We have synthesized PbSe nanorods in wide temperature range 110-170 $^{\circ}$C and different growth times from 25 sec to 5.5 minutes. Here we report the effect of growth time and temperature on the size of nanorod formed. The photoluminescence, absorption and TEM measurements done on different samples taken at different reaction conditions shows that we have good control over size. The photoluminescence decay from the nanorods is nearly single-exponential, indicating minimal surface traps on the nanorods. Also it is seen that the one dimensional growth of the crystal is not possible without adding chloroalkane cosolvent during the synthesis. [Preview Abstract] |
Saturday, March 28, 2015 11:10AM - 11:25AM |
E5.00005: PbS Nanosheets 2D attachement Zhoufeng Jiang, Ghadendra Bhandari, Douglas Dimick, Liangfeng Sun Lead sulfide (PbS) is an important material for optoelectronic devices due to its small and direct energy gaps, small carrier effective masses and high charge mobilities. Making two-dimensional (2D) PbS results in novel properties which may find applications in valleytronics, low-dissipation electronics, and topological insulators. To explore these novel properties, emerging wet-chemistry syntheses have been adapted to make colloidal 2D PbS nanosheets (NSs). It provides an alternative route to the traditional epitaxial methods while making flexible, free-standing NSs. However, the growth mechanism of the PbS NSs is not well-understood yet. In our lab, a photoluminescence spectroscopy method has been developed to characterize the NSs at different growth stages. An intensity-decreasing photoluminescence peak at short wavelength was observed, together with an intensity-increasing, red-shifting peak at long wavelength. These double peaks reveal the decrease of the nanocrystals and the increase of the NSs during the reaction, where the NSs are formed through the 2D attachments of the nanocrystals, which is consistent with the measurements using transmission electron microscopy. The unique feature in the photoluminescence spectra can be used to monitor the growth of the NSs \textit{in situ. } [Preview Abstract] |
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