Half-Metallic and Magnetic Silicon Nanowires Functionalized by Transition-Metal Atoms

Abstract

In this paper we investigate the atomic structure and the mechanical, electronic, and magnetic properties of silicon nanowires (SiNWs) using first-principles plane wave calculations within density functional theory. We examined hydrogen-passivated SiNWs along the [001] direction and studied doping of 3d transition-metal (TM) atoms. Nanowires of different sizes are initially cut from the bulk silicon crystal in rod-like forms, and subsequently their atomic structures are relaxed before and also after the termination of surface dangling bonds by hydrogen atoms. We have first presented an extensive analysis of the atomic structure, stability, and the elastic and electronic properties of bare and hydrogen-terminated SiNWs. The energetics of adsorption and the resulting electronic and magnetic properties are examined for different levels of 3d TM atom coverage. Adsorption of TM atoms generally results in the magnetic ground state. The net magnetic moment increases with increasing coverage. While specific SiNWs acquire half-metallic behavior at low coverage, at high coverage ferromagnetic nanowires become metallic for both spin directions, and some of them have very high spin polarization at the Fermi level. Our results suggest that electronic and spintronic devices with conducting interconnects between them can be fabricated on a single SiNW at a desired order. We believe that our study will initiate new research on spintronic applications of SiNWs.