Magnetism of single-doped paramagnetic tin clusters studied using temperature-dependent Stern–Gerlach experiments with enhanced sensitivity: impact of the diamagnetic ligand field and paramagnetic dopant

Abstract

In this work, the magnetic properties of tetrel clusters Sn_NTM, which are singly doped with transition metals (TM), are investigated. On the one hand, the number of tetrel atoms (N = 11, 12, 14 and 17 with TM = Mn) is varied; on the other hand, different transition metals (N = 14, TM = Cr, Mn, Fe) are studied. Magnetic deflection experiments under cryogenic conditions show that the variation of the number of tetrel atoms strongly changes the magnetic properties of the Mn-doped clusters. It is observed that Sn₁₂Mn, Sn₁₁Mn and Sn₁₄Mn partially show super-atomic behaviour, while spin relaxation occurs in Sn₁₇Mn. Magnetic deflection experiments at higher nozzle temperatures were carried out for the first time enhanced by a second parallel-aligned Stern–Gerlach magnet to achieve larger deflections. The resulting temperature-dependent one-sided deflections are quantitatively analysed using Curie's law and show that Sn₁₇Mn possesses the highest magnetic moment of these clusters, followed by Sn₁₂Mn and Sn₁₁Mn. Sn₁₄Mn shows the lowest magnetic moment. The replacement of Mn by Cr in Sn₁₄Mn leads to a diamagnetic singlet, i.e., the magnetic moment of Cr in Sn₁₄Cr is completely quenched. The replacement of Mn by Fe in turn leads to a paramagnetic species, whereby Sn₁₄Fe is most likely present as a triplet. On this basis, the geometrical and electronic structures are analysed using quantum chemical calculations, indicating an arachno-type structure for Sn₁₄Cr, Sn₁₄Mn and Sn₁₄Fe, which has already been predicted in the literature for Si₁₄Cr. This is experimentally confirmed by deflection of molecular beams with an electric field under cryogenic conditions, suggesting that the arachno-type geometry is crucial for the overall stability of the transition-metal-doped tetrel clusters Sn₁₄TM with TM = Cr, Mn, Fe.