3 research outputs found
Spin dynamics of Mn12-acetate in the thermally-activated tunneling regime: ac-susceptibility and magnetization relaxation
In this work, we study the spin dynamics of Mn12-acetate molecules in the
regime of thermally assisted tunneling. In particular, we describe the system
in the presence of a strong transverse magnetic field. Similar to recent
experiments, the relaxation time/rate is found to display a series of
resonances; their Lorentzian shape is found to stem from the tunneling. The
dynamic susceptibility is calculated starting from the microscopic
Hamiltonian and the resonant structure manifests itself also in .
Similar to recent results reported on another molecular magnet, Fe8, we find
oscillations of the relaxation rate as a function of the transverse magnetic
field when the field is directed along a hard axis of the molecules. This
phenomenon is attributed to the interference of the geometrical or Berry phase.
We propose susceptibility experiments to be carried out for strong transverse
magnetic fields to study of these oscillations and for a better resolution of
the sharp satellite peaks in the relaxation rates.Comment: 22 pages, 23 figures; submitted to Phys. Rev. B; citations/references
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MAGNETIC ORDER AND ANISOTROPY IN FERRIMAGNETIC CHAINS OF Mn(II) IONS AND NITRONYL-NITROXIDE RADICALS
The magnetic properties of single crystals of Mn (hfac)2 NITR with NITR = nitronyl-nitroxide radical with different substituents R have been investigated. The ferrimagnetic chains of alternating Mn II ions and radicals show 3D ferromagnetic order below about 8 K. The anisotropic behaviour is interpreted by taking into account dipolar interactions