The interplay between various internal degrees of freedom of electrons is of fundamental importance for designing high performance electronic devices. A particular instance of this interplay can be observed in...
Identifying the growth factors of nanowires helps in controlling their structure and morphology and determining their optimal growth conditions. This study investigates the effect of titanium substrate in growing TiO 2 nanowires (NWs) with evaporation method. It reveals that the titanium in substrate is indeed the main source of growth. Using the substrate as the only source of growth with regulated amount of accessible oxygen in the furnace, NWs with lengths ranging from 1 to 70 lm were obtained. The results of the experiments show that the nanowires' growth is mainly controlled by diffusion of titanium atoms from the substrate through TiO 2 grain boundaries and surface diffusion toward NWs' tips rather than adsorption from vapor phase. The solid-liquid-solid mechanism including two factors (Ti and O) is proposed and discussed for growth of TiO 2 NWs.
Although the existence of four valley degrees of freedom in the (0 0 1) surface of IV–VI semiconductor topological crystalline insulators (TCIs) provides the opportunity to multiply the valleytronic functionality, it makes the generation of highly polarized valley currents less plausible. We investigate quantum adiabatic valley pumping in (0 0 1) surface of these TCIs and show that applying shear strains and exchange field gives the possibility of control and manipulation of the valley resolved currents with high polarizations. Interchange of polarizations, simply by turning the tensile strain into compressive mode and vice versa, highlights the potential application for valleytronic switching process. Furthermore, since the surface states are robust against disorders, we can increase the lengths of driving regions and pump significantly larger currents without breaking the coherency of the quantum transport regime.
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