Magnetization of Mn_12 Ac in a slowly varying magnetic field: an ab initio study

Abstract

Beginning with a Heisenberg spin Hamiltonian for the manganese ions in the Mn_12 Ac molecule, we find a number of low-energy states of the system. We use these states to solve the time-dependent Schrodinger equation and find the magnetization of the molecule in the presence of a slowly varying magnetic field. We study the effects of the field sweep rate, fourth order anisotropic spin interactions and a transverse field on the weights of the different states as well as the magnetization steps which are known to occur in the hysteresis plots in this system. We find that the fourth order term and a slow field sweep rate are crucial for obtaining prominent steps in magnetization in the hysteresis plots.

arXiv commentLaTeX, 11 pages, 12 eps figures

References in corpus (10)

• High frequency EPR spectra of a molecular nanomagnet provide a key to understand Quantum Tunneling of the Magnetization
• Thermally Activated Resonant Magnetization Tunneling in Molecular Magnets: Mn_12Ac and others
• Observation of the distribution of molecular spin states by resonant quantum tunneling of the magnetization
• Spin Tunneling and Phonon-assisted Relaxation in Mn12-acetate
• Nonadiabatic Landau Zener tunneling in Fe_8 molecular nanomagnets
• Nuclear spin driven resonant tunnelling of magnetisation in Mn12 acetate
• Many-Spin Interactions and Spin Excitations in Mn12
• Nontrivial resonance of nanoscale uniaxial magnets to alternating field
• Resonant Magnetization Tunneling in Mn12 Acetate: The Absence of Inhomogeneous Hyperfine Broadening
• Lattice Distortion Mediated Paramagnetic Relaxation in High-Spin High-Symmetry Molecular Magnets

Cited by in corpus (4)

• Calculating the energy spectra of magnetic molecules: application of real- and spin-space symmetries
• Numerically exact and approximate determination of energy eigenvalues for antiferromagnetic molecules using irreducible tensor operators and general point-group symmetries
• Magnetic energy-level diagrams of high-spin (Mn${}_{12}$-acetate) and low-spin (V${}_{15}$) molecules
• An alternate model for magnetization plateaus in the molecular magnet V_15