Strong spin filtering by silicon nanoparticles with adsorbed bismuth atom clusters: Role of symmetry and electrostatic control of the direction of spin polarization

We present a theoretical study, based on density functional theory and tight-binding modeling, of the electronic structure spin transport properties silicon nanoparticles with adsorbed bismuth atoms. find atoms to form clusters separated by quantum tunnel barriers. predict strong filtering these nanostructures in high conductance regime when source drain leads are connected same cluster low different clusters. relate symmetry obeyed transmission probability matrix system. also that for such systems direction polarization lead can be tuned through large angles even reversed electrostatically simply varying voltage applied gate. Realization silicon-bismuth laboratory is feasible. expect predicted experimentally accessible potentially relevant device applications.