Discovery of a series of silicon-based ferrimagnets in CrMnSin (n=4-20) clusters

Herein, the structural evolution, electronic and magnetic properties of silicon clusters with two different dopants, CrMnSin (n = 4-20) clusters were investigated at density functional theory (DFT) level. Small-sized CrMnSin (n = 4-9) clusters tend to adopt bipyramid-based geometries, while clusters with sizes n = 10 and 11 prefer to opening cage-like structures. For sizes n = 12 to 14, the half-encapsulated structures gradually transform into closed-cage Cr@Si-n structures, with the Mn atom exposed outside. Starting from size 15, both the Cr and Mn atoms are completely encapsulated by silicon atoms. Meanwhile, the Cr and Mn atoms in smaller-sized CrMnSin (n = 4-7) clusters tend to be separated, while they prefer to stay together for larger sizes. Cr atom always acts as electron donor, but not for Mn atom. From the average binding energies, one can conclude that it is easier to form larger size clusters. Smaller and larger sized CrMnSin (n = 4-9 and 19-20) clusters prefer to exhibit ferromagnetic Cr-M-n coupling, while sizes n = 10-18 always exhibit ferrimagnetic state. To our knowledge, the CrMnSin clusters is the first kind of neutral transition-metal doped semiconductor clusters that show ferrimagnetic state within a wide size range.

Automated summary

In this study, the structural evolution, electronic and magnetic properties of silicon clusters with two different dopants, CrMnSin (n = 4-20) clusters, were investigated using density functional theory (DFT). It was found that small-sized clusters tend to adopt bipyramid-based geometries, while larger clusters prefer opening cage-like structures. The binding energies suggest that larger size clusters are easier to form. Smaller and larger clusters exhibit ferromagnetic Cr-M-n coupling, while medium-sized clusters always exhibit ferrimagnetic state. To the best of our knowledge, the CrMnSin clusters are the first kind of neutral transition-metal doped semiconductor clusters to show ferrimagnetic state within a wide size range.