in this thesis,spin dependend transport and electron transport through of ng/sg(graphene/ superconductor graphen) are studied in the junction of ng/fgt/sg. due to andreev reflection conductance increases in the presence of superconductor graphene.also, by applying a voltage gate on a superconductor, fermi level shifts and the conductance is independent of ferromagnatic substrate. also, the cond...

Charge and spin transport properties of a clean $SNS$ Josephson junction (triplet superconductor-normal metal-triplet superconductor) are studied using the quasiclassical Eilenberger equation of Green’s function. Our system consists of two p-wave superconducting crystals separated by a Copper nano layer. Effects of thickness of normal layer between superconductors on the spin and charge current...

We have investigated the magnetic properties of three-dimensional topological insulators, doped with magnetic atoms. The spin-orbit locking of surface electrons results in interesting magnetic behaviors, absent in conventional insulators without spin-orbit coupling. In particular, the ferromagnetic-paramagnetic transition temperature has a strong dependence on different system parameters. Here,...

We theoretically demonstrate the interplay of uniform spin-orbit coupling and uniform Zeeman magnetic field on the topological properties of one-dimensional double well nano wire which is known as Su-Schrieffer-Heeger (SSH) model. The system in the absence of Zeeman magnetic field and presence of uniform spin-orbit coupling exhibits topologically trivial/non–trivial insulator depending on the h...

In this study, the effect of four-spin exchanges between the nearest and next nearest neighbor spins of honeycomb lattice on the phase diagram of S=3/2 antiferomagnetic Heisenberg model is considered with two-spin exchanges between the nearest and next nearest neighbor spins. Firstly, the method is investigated with classical phase diagram. In classical phase diagram, in addition to Neel order,...