Transverse Magnetic Anisotropy in Mn12-acetate: Direct Determination by Inelastic Neutron Scattering

Abstract

A high resolution inelastic neutron scattering (INS) study of fully deuterated Mn${}_{12}$-acetate provides the most accurate spin Hamiltonian parameters for this prototype single molecule magnet so far. The Mn${}_{12}$-clusters deviate from axial symmetry, a non-zero rhombic term in the model Hamiltonian leading to excellent agreement with observed positions and intensities of the INS peaks. The following parameter set provides the best agreement with the experimental data: $D=-0.0570(1)$ meV, $B_4^0=-2.78(7)\cdot 10^{-6}$ meV, $B_4^4=-3.2(6)\cdot 10^{-6}$ meV and $\mid$\textit{E}$\mid =6.8(15)\cdot 10^{-4}$ meV. Crystal dislocations are not the likely cause of the symmetry lowering. Rather, this study lends strong support to a recently proposed model, which is based on the presence of several molecular isomers with distinct spin Hamiltonian parameters.

4 pages, 4 figures

References in corpus (11)

• High frequency EPR spectra of a molecular nanomagnet provide a key to understand Quantum Tunneling of the Magnetization
• Low energy magnetic excitations of the Mn_{12}-acetate spin cluster observed by neutron scattering
• The origin of second-order transverse magnetic anisotropy in Mn12-acetate
• Definitive spectroscopic determination of the transverse interactions responsible for the magnetic quantum tunneling in Mn12-acetate
• Spin tunneling via dislocations in Mn-12 acetate crystals
• Crossover between Thermally Assisted and Pure Quantum Tunneling in Molecular Magnet Mn12-Acetate
• Symmetry of Magnetic Quantum Tunneling in Single Molecule Magnet Mn12-acetate
• Phonon-assisted tunneling in the quantum regime of Mn12-ac
• Inelastic Neutron Scattering Study of Mn_12-Acetate
• Second-order transverse magnetic anisotropy induced by disorders in the single-molecule magnet Mn12
• Magnetic Field Effects on the Far-Infrared Absorption in Mn_12-acetate

Cited by in corpus (9)

• Magnetic Cluster Excitations
• Magnetic Quantum Tunneling: Insights from Simple Molecule-Based Magnets
• Many-spin effects in inelastic neutron scattering and electron paramagnetic resonance of molecular nanomagnets
• Quantum dynamics of the Neel vector in the antiferromagnetic molecular wheel CsFe8
• Exchange-coupling constants, spin density map, and Q dependence of the inelastic neutron scattering intensity in single-molecule magnets
• Magnetic relaxation studies on a single-molecule magnet by time-resolved inelastic neutron scattering
• On the anisotropy barrier reduction in fast relaxing Mn12 single-molecule magnets
• Unravelling the Spin Dynamics of Molecular Nanomagnets with Four-Dimensional Inelastic Neutron Scattering
• The effect of uniaxial pressure on the magnetic anisotropy of the Mn_{12}-Ac single-molecule magnet