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Using non-equilibrium Green's function, we study the spin-dependent electron transport properties in a zigzag silicene nanoribbon. To produce and control spin polarization, it is assumed that two ferromagnetic strips are deposited on the both edges of the silicene nanoribbon and an electric field is perpendicularly applied to the nanoribbon plane. The spin polarization is studied for both parallel and anti-parallel configurations of exchange magnetic fields induced by the ferromagnetic strips. We find that complete spin polarization can take place in the presence of perpendicular electric field for anti-parallel configuration and the nanoribbon can work as a perfect spin filter. The spin direction of transmitted electrons can be easily changed from up to down and vice versa by reversing the electric field direction. For parallel configuration, perfect spin filtering can occur even in the absence of electric field. In this case, the spin direction can be changed by changing the electron energy. Finally, we investigate the effects of nonmagnetic Anderson disorder on spin dependent conductance and find that the perfect spin filtering properties of nanoribbon are destroyed by strong disorder, but the nanoribbon retains these properties in the presence of weak disorder.

Optical and photothermal properties of graphene coated gold nanoparticles show that these nanoparticles are more suitable candidates for photothermal therapy applications.

We study the optical and photothermal properties of graphene coated gold−silver alloy hollow nanoshells (Au−Ag HNSs) using the effective medium theory combined with the Pennes bioheat and Arrhenius equations. To increase the stability of Au−Ag HNSs in the presence of oxidants, acid, and heating, we propose the use of graphene as a protective shell on Au−Ag HNSs in photothermal therapy (PTT) applications. Calculating the extinction efficiency in tumor tissue, we show that the surface plasmon resonant (SPR) peak of graphene coated Au−Ag HNSs can be easily adjusted within a wide range of biological windows by changing the inner radius, the Au−Ag shell thickness, and the alloy composition of Au−Ag. In addition, the effect of concentration of nanoparticles and the number of graphene layers on the temperature rise in the tumor tissue are investigated.To achieve a comprehensive study, the thermal damage in tumor tissue is also investigated and the region of tumor in which the irreversible thermal damage can occur is determined. Our results suggest that graphene coated Au−Ag HNSs can be used as an excellent class of nanoagents for PTT applications.

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