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Annealing is one of the stages of FePt nanoparticles preparation, during which the transition to a compositionally ordered phase occurs. In order to size and shape control of the nanoparticles in the mentioned stage, it is needed that they be distributed on a suitable surface. In the present work, the spin-coating method is suggested for preparing monolayer from L12-FePt3nanoparticles colloidal solution on SiO2/Si substrates. FePt3nanoparticles were gradually deposited as droplets on the center of a 500 rpm rotating substrate. This step was performed in hexane vapor atmosphere without any stopping time. The analyses revealed that a uniform surface distribution was formed so that, after annealing at 600 °C for 1 h the 6.1 nm L12-FePt3nanoparticles were spherical in shape with standard deviation of 1.5 nm.

I theoretically investigate the spin Polarization and transmission of the electrons in a nanostructure consisting barriers with periodic, parallel and also anti parallel magnetization .also I investigate polarization when distance between barriers is constant, or is increased, or is decreased periodically. These observable quantities are found to be strongly affected by both the magnetic configuration and the number of the periodic magnetic barriers. When the number of periods increases, in parallel magnetization for periodic increasing distance the polarization is enhanced so in parallel configuration it is better that distance between barriers to be increasing periodically. I investigate Polarization in these configuration in both delta function approximation and modulated magnetic barriers in x direction. This Polarization can be used in spintronics device.

The spin-polarized transport is investigated in a magnetic tunnel junction which consists of two ferromagnetic electrodes separated by a magnetic barrier and a nonmagnetic metallic spacer placed in distance above the two dimensional electron gas (2DEG) in presence of an inhomogeneous external modulated magnetic field and a perpendicular wave vector dependent effective potential. Based on the transfer matrix method and the nearly-free-electron approximation the dependence of the conductance and spin polarization on the Fermi energy of the electrons are studied theoretically the. strong oscillations with large amplitude investigated in spin polarization in terms of the Fermi energy due to the inhomogeneous magnetic field. The conductance in terms of the Fermi energy shows no oscillation in low energy but has a strong pick in middle region. this results may be useful for the development of spin electronic devices based on coherent transport, or may be used as a tunable spin-filter.