High Magnetic Moments in Manganese‐Doped Silicon Clusters

Abstract

We report on the structural, electronic, and magnetic properties of manganese-doped silicon clusters cations, Si(n)Mn(+) with n=6-10, 12-14, and 16, using mass spectrometry and infrared spectroscopy in combination with density functional theory computations. This combined experimental and theoretical study allows several structures to be identified. All the exohedral Si(n)Mn(+) (n=6-10) clusters are found to be substitutive derivatives of the bare Si(n+1)(+) cations, while the endohedral Si(n)Mn(+) (n=12-14 and 16) clusters adopt fullerene-like structures. The hybrid B3P86 functional is shown to be appropriate in predicting the ground electronic states of the clusters and in reproducing their infrared spectra. The clusters turn out to have high magnetic moments localized on Mn. In particular the Mn atoms in the exohedral Si(n)Mn(+) (n=6-10) clusters have local magnetic moments of 4 μ(B) or 6 μ(B) and can be considered as magnetic copies of the silicon atoms. Opposed to other 3d transition-metal dopants, the local magnetic moment of the Mn atom is not completely quenched when encapsulated in a silicon cage.

Nature of the interaction between rare gas atoms and transition metal doped silicon clusters: the role of shielding effects

“…The hybrid B3P86 functional is chosen because its good performance for transition metal doped silicon clusters was proven in the previous studies in which computed vibrational spectra were compared with experimental infrared multiphoton dissociation (IR-MPD) spectra. 9,21 A comparison of other functionals including the M06 functional, 22 which is well known to be suitable for weakly bound systems, has been already made in the previous study on the structure determination of Si n Mn + . 21 M06 calculations give similar energetics to B3P86, but still do not describe the system that well, even when including the RG ligands, at least in terms of the vibrational spectra.…”

“…9,21 A comparison of other functionals including the M06 functional, 22 which is well known to be suitable for weakly bound systems, has been already made in the previous study on the structure determination of Si n Mn + . 21 M06 calculations give similar energetics to B3P86, but still do not describe the system that well, even when including the RG ligands, at least in terms of the vibrational spectra. In the present study, the RG-cluster binding energies are also calculated using the two functionals (B3P86, M06) (cf.…”

“…21 The potential energy surface of the cluster was carefully investigated by searching various structural isomers at different possible spin states. The Si n Mn + clusters were concluded to favor the high-spin states such as septet and quintet, while low-spin states (singlet and triplet states) are less stable.…”

“…For Si 7 Cr + , Si 7 Mn + , and Si 7 Cu + such structures have been identified by combined IRMPD spectroscopy and DFT studies. 9,21,30 No IRMPD data are available to confirm the computed structure for Si 7 To investigate further the orbital overlap, the overlap populations (based on the C-squared population analysis, SCPA 31 ) between the AOs of Ar and TM dopant atoms in Com-A of Si 7 TM + ÁAr are plotted in Fig. 5.…”

Structural determination of niobium-doped silicon clusters by far-infrared spectroscopy and theory

“…[6][7][8][9][10][11][12] Different from carbon clusters that usually show sp 2 hybridization, bonding in pure silicon clusters occurs through sp 3 hybridization and thus they are more chemically reactive due to the existence of unsaturated dangling bonds on the clusters' surface, making them less suitable as nanoscale building blocks. 13 However, it has been found that silicon clusters can be stabilized by doping with transition metal (TM) atoms, [14][15][16] and by now a great number of studies, both experimentally [17][18][19][20][21][22][23][24][25][26][27][28][29] and theoretically, [30][31][32][33][34][35][36] have explored the structures and electronic properties of TM-doped silicon clusters for their potential use in silicon-based nanomaterials. In fact, doping silicon clusters with appropriate transition metal atoms [37][38][39][40][41] can reduce the number of dangling bonds on the cluster surface or even fully saturate them via pd hybridization, and thereby change the geometrical structures and chemical reactivities compared to pure silicon clusters.…”