Orbit and spin resolved magnetic properties of size selected [Co_nRh]⁺ and [Co_nAu]⁺ nanoalloy clusters

Abstract

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 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.

Magnetic deflection of neutral sodium-doped ammonia clusters

“…The original Stern-Gerlach experiment was designed to determine the magnetic moment of isolated silver atoms; 22 later various other isolated atoms, 23 several molecules with a nonzero spin S [24][25][26][27][28][29][30][31][32][33][34] and metallic and bi-metallic clusters [35][36][37][38][39][40][41][42][43][44][45][46][47] were investigated with Stern-Gerlach setups (except for ref. 46). For molecular systems and metal clusters, additional degrees of freedom like vibrations and rotations are accessible compared with atomic systems.…”

Quantum size effects of small, size-selected and deposited CoRh clusters on Ni

“…For these systems an induced magnetic moment on the Rh site was reported, strongly depending on the magnetic environment. Calculations on free neutral [15][16][17][18] as well as experiments on free ionic [19] CoRh clusters showed that the orbital and spin magnetic moments can be either enhanced or reduced if compared to the pure Co clusters. These non-monotonous trends are linked to the complex interplay between the cluster size, the geometry and its composition.…”

“…Alloying of Co with Rh has been studied experimentally and theoretically in a variety of systems, e.g. alloys [5,6], multilayers [7,8], nanoparticles [9][10][11][12][13][14] and clusters [15][16][17][18][19]. For these systems an induced magnetic moment on the Rh site was reported, strongly depending on the magnetic environment.…”

Structural determination of neutral Co n clusters (n = 4–10,13) through IR–UV two-color vibrational spectroscopy and DFT calculations

“…Moreover, a marked increase in magnetic moment per atom as compared to the bulk value is observed, which can in part be explained by the reduced hybridization of 3d and 4s orbitals and is a topic of many computational studies [12][13][14][15][16][17][18]. A recent spur of experiments has addressed the disentanglement of spin and angular magnetic moments in size-selected cationic 3d metal clusters through x-ray magnetic circular dichroism (XMCD) spectroscopy [19][20][21][22][23]. Here, it was found that cationic cobalt clusters exhibit a strong increase in orbital contribution with reduced cluster size [19].…”