Magnetic properties of transition-metal impurities in silicon quantum dots

First-principles calculations have been conducted to investigate the magnetic properties of 3d and 4d transitional-metal (TM) atoms doped in hydrogen-passivated silicon quantum dots. The TM impurities exhibit almost identical magnetic behavior in the quantum dots of different sizes. The magnetic moments for most 3d and 4d TM atoms are completely quenched by the silicon hosts, while the magnitudes of the remaining moments for V, Cr, Mn, Nb, Mo, and Tc impurities are significantly reduced from those of free atoms. The moments of these 3d atoms are higher than those of the 4d atoms of the same family. Doping of TM atoms in different sites of lattice and the dopants of more than one atom are also considered. The structural and bonding properties of the TM-doped silicon quantum dots are discussed. The finding of magnetic properties makes them attractive for developing nanoscale magnetic species for spintronics.