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We have investigated carrier transport in SiO2/nc-Si/SiO2 multi-layers by room temperature current-voltage measurements. Resonant tunneling signatures accompanied by current peaks are observed. Carrier transport in the multi-layers were analyzed by plots of ln(I/V²) as a function of 1/V and ln(I) as a function of V1/2. Results suggest that besides films quality, nc-Si and barrier sub-layer thicknesses are important parameters that restrict carrier transport. When thicknesses are both small, direct tunneling dominates carrier transport, resonant tunneling occurs only at certain voltages and multi-resonant tunneling related current peaks can be observed but with peak to valley current ratio (PVCR) values smaller than 1.5. When barrier thickness is increased, trap-related and even high field related tunneling is excited, causing that multi-current peaks cannot be observed clearly, only one current peak with higher PVCR value of 7.7 can be observed. While if the thickness of nc-Si is large enough, quantum confinement is not so strong, a broad current peak with PVCR value as high as 60 can be measured, which may be due to small energy difference between the splitting energy levels in the quantum dots of nc-Si. Size distribution in a wide range may cause un-controllability of the peak voltages. [ABSTRACT FROM AUTHOR]

The coercivity and grain size of equiatomic FePt alloy films annealed at 500 and 600 °C with different magnetic fields of 0–70 kOe have been investigated. It is found that applying a magnetic field with appropriate strength during postdeposition annealing not only enhances the coercivity but also reduces the grain size of the FePt films. Measurements of the microstructure and magnetic properties of the FePt films reveal that the coercivity is affected by both the ordered volume fraction and a microstructure factor that is related to the ordered volume fraction. The high coercivity in FePt films annealed with an appropriate strength of magnetic field is due to an increasing density of magnetic domain wall pinning sites concurrent with an increasing fraction of the ordered phase. [ABSTRACT FROM AUTHOR]

An expression is derived for soliton phase jitter in soliton transmission with higher-order effects in the presence of nonlinear gain and filters. It is demonstrated that soliton phase jitter can be suppressed efficiently by nonlinear gain in addition to filters not only for long duration solitons but also for ultrashort solitons provided that the nonlinear gain coefficients satisfy specific conditions. This scheme offers an alternative means for the development of ultralong distance soliton transmission systems using differential phase-shift keying (DPSK), and exploits a robust technique to achieve a higher-speed soliton communication system using DPSK. [ABSTRACT FROM AUTHOR]

We demonstrate that by spatially modulating the Bessel optical lattice where a Bose-Einstein condensate is loaded, we get tunable rotary orbits of nonlinear lattice modes. We show that the radially expanding or shrinking Bessel lattice can drag the nonlinear localized modes to orbits of either larger or smaller radii and the rotary velocity of nonlinear modes can be changed accordingly. The localized modes can even be transferred to the Bessel lattice core when the localized modes' rotations are stopped. Effects beyond the quasi-particle approximation such as destruction of the nonlinear modes by nonadiabatic dragging are also explored. [ABSTRACT FROM AUTHOR]