Magnetic Enhancement in Cobalt-Manganese Alloy Clusters

Abstract

Magnetic moments of Co(N)Mn(M) and Co(N)V(M) clusters (N < or = 60; M < or = N/3) are measured in molecular beams using the Stern-Gerlach deflection method. Surprisingly, the per atom average moments of Co(N)Mn(M) clusters are found to increase with Mn concentration, in contrast to bulk CoMn. The enhancement with Mn doping is found to be independent of cluster size and composition in the size range studied. Meanwhile, Co(N)V(M) clusters show reduction of average moments with increasing V doping, consistent with what is expected in bulk CoV. The results are discussed within the virtual bound states model.

Magnetism in small bimetallic Mn-Co clusters

“…They have also found that the total enhancement in the magnetic moment to be 1.7 µ B /Mn-substitution, and is independent of the cluster size n and composition, which is justified by the virtual bond state model. 31 The present calculation is in good agreement and we find this enhancement to be 2 µ B /Mn-substitution (Tables I-IV) as long as cluster is ferromagnetic (Co-rich). …”

“…More recently Yin et al have measured the magnetic moments of Mn x Co y (y ≤60; x≤y/3) clusters and found an increase in peratom magnetic moment for Co-rich Mn x Co y cluster with increasing Mn concentration. 31 This enhancement in moment due to Mn doping is independent of cluster size and composition. On the other hand, for Mn-rich clusters, for more than 40% Mn concentration, the average magnetic moment of Mn x Co y cluster decreases with increasing Mn concentration.…”

“…However, the magnitudes of individual Mn and Co moments could not be measured, and consequently the nature of magnetic coupling can not be concluded in a SG experiment. Motivated by these recent SG experiments, 27,31 in the present paper, we study Mn x Co y clusters from first-principles in the size range n=2-5. In order to make a direct comparison to the experiments we also study Mn 2 Co 11 cluster, which lies within the experimental regime.…”

Giant magnetic moment of the core‐shell Co13@Mn20 clusters: First‐principles calculations

“…Recently, the magnetic moments of the Co n Mn m and Co n V m clusters were measured in molecular beams with the Stern-Gerlach deflection method. 7 And it was found that, for the Co-rich Co n Mn m clusters, the average magnetic moments increase with the increasing Mn concentration, which is in contrast to bulk CoMn. However, for the Co n V m clusters, the average magnetic moments decrease with the increasing V dopant.…”

Structural and magnetic properties of bimetallic Co n − 1Cr clusters with density functional theory

“…Besides, the heterogeneous magnetic structures offer opportunities for clusterassembled materials with new functions for magnetic recording and medical applications [1,2]. To date, a few studies have been made on the structural and magnetic properties of cobalt-based bimetallic TM clusters [3][4][5][6][7][8][9][10][11]. Experimentally, magnetic deflection study of Co n Bi m suggested that the clusters adopt segregated structures with ferromagnetic Co n "cores" surrounded by the Bi atom shell [3].…”