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Non-equilibrium molecular dynamic simulations reveal that the thermal conductivity of ultrathin carbon nanotube (CNT)(2, 1) is significantly suppressed upon hydrogenation. The addition of hydrogen atoms to two-coordinated carbon atoms lowers the participation ratios of phonon modes, thus indicating that the spatial distribution of phonons becomes localized. Furthermore, the phonon lifetimes are remarkably shortened in hydrogenated CNT(2, 1) (HCNT(2, 1)) compared with those of bare CNT(2, 1). The lowered participation ratios and lifetimes of phonon modes are responsible for the significant reduction of thermal conductivity in HCNT(2, 1). Our study is also helpful for understanding the weakened thermal transport abilities in carbon polymers, namely, the cross links formed between individual polymer chains will hinder the thermal conduction along polymers, even though the single straight carbon polymer has a high and divergent thermal conductivity. [ABSTRACT FROM AUTHOR]

3.0 MeV Ni2+ in the beam doses from 1×1013 to 9×1014 ions/cm2 are implanted into LiNbO3 single crystals at room temperature. After 300 °C annealing for 30 min in air ambient, dark mode measurement is done by the prism-coupling technique. Waveguides from both raised extraordinary index layer and barrier-confined are formed by low and high beam dose implantation, respectively. In the samples implanted by mediate beam doses, a phenomenon of “missing mode” is observed. The experimental results are analyzed and compared with the simulated results from a theoretical model, which is based on the assumption that the change of index induced by implantation is mainly governed by degradation of polarization and reduction of material density. With a fiber probe, the waveguide loss from single transverse magnetic mode is measured, which is about 3 dB/cm. [ABSTRACT FROM AUTHOR]

3.0 MeV Ni2+ in the beam doses from 1×1013 to 9×1014 ions/cm2 are implanted into LiNbO3 single crystals at room temperature. After 300 °C annealing for 30 min in air ambient, dark mode measurement is done by the prism-coupling technique. Waveguides from both raised extraordinary index layer and barrier-confined are formed by low and high beam dose implantation, respectively. In the samples implanted by mediate beam doses, a phenomenon of “missing mode” is observed. The experimental results are analyzed and compared with the simulated results from a theoretical model, which is based on the assumption that the change of index induced by implantation is mainly governed by degradation of polarization and reduction of material density. With a fiber probe, the waveguide loss from single transverse magnetic mode is measured, which is about 3 dB/cm. [ABSTRACT FROM AUTHOR]

Graphene nanostructures are potential building blocks for nanoelectronic and spintronic devices. However, the production of monolayer graphene nanostructures with well-defined zigzag edges remains a challenge. In this paper, we report the patterning of monolayer graphene nanostructures with zigzag edges on hexagonal boron nitride (h-BN) substrates by an anisotropic etching technique. We found that hydrogen plasma etching of monolayer graphene on h-BN is highly anisotropic due to the inert and ultra-flat nature of the h-BN surface, resulting in zigzag edge formation. The as-fabricated zigzag-edged monolayer graphene nanoribbons (Z-GNRs) with widths below 30 nm show high carrier mobility and width-dependent energy gaps at liquid helium temperature. These high quality Z-GNRs are thus ideal structures for exploring their valleytronic or spintronic properties. [ABSTRACT FROM AUTHOR]

We report the coexistence of nonvolatile resistive and magnetization switching in Pt/NiO/ Nb:SrTiO3 heterostructures. These structures exhibit bipolar resistive switching (RS) behavior with multilevel RS characteristics, a maximum RS ratio of 105, and stable endurance properties. Under simple application of voltage pulses, the saturation magnetization of the NiO layer increases by up to three times in the different resistance states. This electrical modulation of both the resistive and magnetization switching properties is attributed to the migration of oxygen vacancies and charge trapping and detrapping at the heterojunction interface. Our results provide a pathway towards the electrical switching of both resistance and magnetization, which is likely to be useful for RS and magnetic multifunctional device applications. [ABSTRACT FROM AUTHOR]

We have used the introduction of shallow hole traps in poly(3-hexyl-thiophene) to test one of the predictions of the bipolaron theory of magnetoconductance (MC). The results show that the introduction of shallow traps effectively increases the degree of energetic disorder in the transport states whilst not affecting the position of the Fermi level and that this results in an increase in the MC response. These results are demonstrated to be in qualitative agreement with the theory and suggest one mechanism through which trap states may affect the MC response of organic semiconductors. This work presents a controllable way of chemical doping to engineer a change in absolute current at a given bias depending on the choice of anodes. It also allows for tuning the magnitude of negative MC response and electroluminescence efficiency under different driving conditions. [ABSTRACT FROM AUTHOR]

The magnetic field effects on the electroluminescence of aluminium tris-(8-hydroxyqinoline) (Alq3) based organic light emitting diodes have been investigated by varying the electron/hole ratio in the emissive layer. Experimental results reveal that a negative high field effect in the magnetoelectroluminescence (MEL) can be found in devices with very low triplet exciton concentration at room temperature. This suggests triplet-triplet annihilation cannot be used to explain the negative high field MEL in the Alq3 system. Our results suggest that hole-exciton interaction may be the origin of the negative high field MEL and also, in parallel with this interaction, there is also the more common positive high field process occurring which has been tentatively attributed to electronexciton interactions. The competition between these different processes decides the final shape of the MEL at high fields. [ABSTRACT FROM AUTHOR]