Orbit and spin resolved magnetic properties of size selected ConRh (+) and ConAu (+) nanoalloy clusters

Bi-metallic nanoalloys of mixed 3d–4d or 3d–5d elements are promising candidates for technological applications. The large magnetic moment of the 3d materials in combination with a high spin–orbit coupling of the 4d or 5d materials give rise to a material with a large magnetic moment and a strong magnetic anisotropy, making them ideally suitable in for example magnetic storage devices. Especially for clusters, which already have a higher magnetic moment compared to the bulk, these alloys can profit from the cooperative role of alloying and size reduction in order to obtain magnetically stable materials with a large magnetic moment. Here, the influence of doping of small cobalt clusters on the spin and orbital magnetic moment has been studied for the cations [Co8−14Au]+ and [Co10−14Rh]+. Compared to the undoped pure cobalt [CoN]+ clusters we find a significant increase in the spin moment for specific CoN−1Au+ clusters and a very strong increase in the orbital moment for some CoN−1Rh+ clusters, with more than doubling for Co12Rh+. This result shows that substitutional doping of a 3d metal with even just one atom of a 4d or 5d metal can lead to dramatic changes in both spin and orbital moment, opening up the route to novel applications.