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 [Co 8−14 Au] + and [Co 10−14 Rh] + . Compared to the undoped pure cobalt [Co N ] + clusters we find a significant increase in the spin moment for specific Co N −1 Au + clusters and a very strong increase in the orbital moment for some Co N −1 Rh + clusters, with more than doubling for Co 12 Rh + . 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. XMCD measurements on doped Co clusters in the gas phase reveal their fluctuating spin and orbital magnetic moments.