Hydrogen adsorption and magnetic behavior of Fen and Con clusters:: Controlling the magnetic moment and anisotropy one atom at a time -: art. no. 165406

Theoretical studies to investigate the effect of H absorption on the magnetic moment of small Fe-n and Co-n clusters have been carried out using gradient corrected density-functional approach. Our studies on clusters containing up to four transition metal and 2 H atoms show that the successive addition of H atoms can lead to monotonic or oscillatory change from the free cluster magnetic moment. A detailed analysis of the density of electronic states shows that the variations in the magnetic moment can be related to the location of the lowest unoccupied molecular orbital in the parent cluster. It is shown that the addition of hydrogen can substantially change the magnetic anisotropy. In particular Co3H2 is shown to exhibit magnetic anisotropy that is higher than any of the known anisotropies in the molecular nanomagnets.