Stern-Gerlach Experiments on Fe@Sn₁₂: Magnetic Response of a Jahn–Teller Distorted Endohedrally Doped Molecular Cage Cluster

Abstract

The magnetic response of the Fe@Sn 12 cluster is investigated by magnetic beam deflection experiments. In contrast to Mn@Sn 12 , the molecular beam of this cluster is deflected almost exclusively toward increasing field, also at low temperatures, supposable due to Jahn−Teller induced distortions of the tin cage. The magnitude of the magnetic dipole moment is extracted from the shift of the beam profile and provides evidence for a (partially quenched) contribution of electronic orbital angular momentum to the magnetic dipole moment. ■ INTRODUCTIONThe sensitivity of the optical, dielectric, catalytic, and magnetic properties of atomic clusters to size, composition, and temperature has been discussed extensively in recent years and is of major interest regarding possible technological applications. 1,2 While the interaction with their environment has an additional impact on the properties of deposited clusters, 1 molecular beam experiments allow studying the intrinsic properties of nanoscale clusters isolated in the gas phase. This provides the opportunity not only to identify particles with valuable properties, but to probe the evolution of physical properties of matter in this regime of limited dimensions.Recently, we have closely investigated the impact of the topology of a diamagnetic cage on the magnetic response of clusters with a paramagnetic center. For that purpose we studied Mn/Sn N clusters with N = 9−18 by magnetic and electric beam deflection experiments, taking into account the ground state isomers of the clusters as identified by density functional theory (DFT) methods and confirmed by the dielectric response. 3 With our setup and well chosen source conditions, the vibrational temperature of the clusters is sufficiently low at 16 K nozzle temperature, so that fractions of the ensemble of each size of the manganese-doped tin clusters are rigid, that is, in the vibrational ground state. In the rigid-rotor limit, the magnetic response of the clusters is very sensitive to the environment of the transition metal center, formed by the varying number of tin atoms. The temperaturedependent magnetic beam deflection studies show that only the rigid icosahedral environment of Mn@Sn 12 leads to superatomic paramagnetic behavior, 4 while other cage sizes and, hence, geometries induce net magnetization of the cluster beam, even in the vibrational ground state. The microstate degeneracy of the unpaired electrons is split by the low symmetry environment, giving rise to (permanent) zero field splitting (ZFS). The ZFS in turn couples the rotation of a cluster with its electronic angular momentum, and avoided crossings among states in the representation of total angular momentum ultimately provide an adiabatic mechanism for the magnetization of the rigid clusters, that is, orientation of the average magnetic dipole moment. 3−6 The vibrationally excited clusters on the other hand show only single sided deflection of the molecular beam, independent of the cage size. Correlation of the calculated vibrational ground state...

On the position of La, Lu, Ac and Lr in the periodic table: a perspective

“…[35][36][37][38][39][40][41][42] Thus, there is a plethora of captivating metal atom or ion encapsulated Si n -, Ge n -, Sn n and Pb 12 2-clusters that have been experimentally and theoretically examined. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] A few examples include kinetically stable noble gas atom or dimer (H 2 and He 2 ) encapsulated Pb 12 2and Sn 12 2clusters which have been predicted by our group. 59 Addressing the point of stability, it has additionally been shown that encapsulated Pb 12 2and Sn 12 2clusters preserved their structural integrity even at high temperatures of 700 K. 59 Delving further, considering their similar cage sizes, the possibility of having an Lr@C 60 cluster 60 makes the prediction of Lr or Lu encapsulated Pb 12 2and Sn 12 2clusters realisable.…”

The role of TM’s (M’s) d valence electrons in TM@X12 and M@X12 clusters

“…To achieve magnetic superatoms, a singely magnetic TM atom were embedded into a small simple-metal cluster, because either the D-state (magnetic state) of superatoms almost exclusively comes from atomic d-state (that is, for the filling superatomic shells, atomic d electrons are thought as delocalized valence electrons) or its superatomic D-state (magnetic state) hybridize strongly with atomic d-states (that is, atomic d electrons are strongly localized and not fill superatomic shells) in previous reports. 6,9,10,12,13,[29][30][31][32][33][34][35] The exchange-splitting between the majority of superatomic D shells (atomic d shells) and their minority states can resulted in by both cases of above, so a superatom can have a corresponding spin magnetic moment. However, the spin magnetic moment of one superatom may be very vulnerable to its surrounding environments, which restricts the practical applications of superatoms.…”

Insights into the structural, electronic and magnetic properties of V-doped copper clusters: comparison with pure copper clusters

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