Crystal lattice desolvation effects on the magnetic quantum tunneling of single-molecule magnets

2009/07/31 by G. Redler, Gage Redler, C. Lampropoulos +13 · 32 citations
Chemistry · Materials Science · Physics and Astronomy · #Chemistry #Condensed matter physics #Crystallography #Electron paramagnetic resonance #Lanthanide and Transition Metal Complexes #Lattice (music) #Magnetic field #Magnetism in coordination complexes #Magnetization #Nuclear magnetic resonance #Physics #Porphyrin and Phthalocyanine Chemistry #Quantum mechanics #cond-mat.mes-hall

paper · pdf · doi:10.1103/physrevb.80.094408

published in Physical Review B 80(9) (American Physical Society) · 17 pages, 6 figures, accepted for publication in Phys. Rev. B

arxiv created 2009/08/13 · openalex publication_date 2009/09/16 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

High-frequency electron paramagnetic resonance (HFEPR) and alternating current (ac) susceptibility measurements are reported for a new high-symmetry Mn₁₂ complex, [Mn₁₂O₁₂(O₂CCH₃)₁₆(CH₃OH)₄]\ensuremath⋅CH₃OH. The results are compared to those of other high-symmetry spin S=10 Mn₁₂ single-molecule magnets (SMMs), including the original acetate, [Mn₁₂(O₂CCH₃)₁₆(H₂O)₄]\ensuremath⋅2CH₃CO₂H\ensuremath⋅4H₂O, and the [Mn₁₂O₁₂(O₂CCH₂Br)₁₆(H₂O)₄]\ensuremath⋅4CH₂Cl₂ and [Mn₁₂O₁₂(O₂CCH₂Bu^t)₁₆(CH₃OH)₄]\ensuremath⋅CH₃OH complexes. These comparisons reveal important insights into the factors that influence the values of the effective barrier to magnetization reversal, U_eff, deduced on the basis of ac susceptibility measurements. In particular, we find that variations in U_eff can be correlated with the degree of disorder in a crystal which can be controlled by desolvating (drying) samples. This highlights the importance of careful sample handling when making measurements on SMM crystals containing volatile lattice solvents. The HFEPR data additionally provide spectroscopic evidence suggesting that the relatively weak disorder induced by desolvation influences the quantum tunneling interactions and that it is under-barrier tunneling that is responsible for a consistent reduction in U_eff that is found upon drying samples. Meanwhile, the axial anisotropy deduced from HFEPR is found to be virtually identical for all four Mn₁₂ complexes, with no measurable reduction upon desolvation.

Citations

• Detailed single-crystal EPR line shape measurements for the single-molecule magnetsFe8BrandMn12−acetate
• Fabrication of nanogapped single-electron transistors for transport studies of individual single-molecule magnets
• Distribution of internal transverse magnetic fields in aMn12-based single molecule magnet
• Symmetry of Magnetic Quantum Tunneling in Single Molecule MagnetMn12-Acetate
• Rotating cavity for high-field angle-dependent microwave spectroscopy of low-dimensional conductors and magnets
• Spin-parity dependent tunneling of magnetization in single-molecule magnets
• Effects ofD-strain,g-strain, and dipolar interactions on EPR linewidths of the molecular magnetsFe8andMn12