Regensburg 2002 – wissenschaftliches Programm
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MA: Magnetismus
MA 11: Molekularer Magnetismus
MA 11.4: Vortrag
Mittwoch, 13. März 2002, 15:15–15:30, H22
Magnetic Hole Burning in Molecular Magnets — •M. Dressel1, B. Gorshunov1, K. Rajagopal1, S. Vontragool1, and A.A. Mukhin2 — 11. Physikalisches Institut, Universität Stuttgart — 2General Physics Institute, Russian Academy of Sciences, Moscow
Using a new high frequency ESR method (frequency range 50 GHz to 1.5 THz, external magnetic field up to 8 Tesla), we have studied magnetic excitations and relaxation phenomena in the molecular magnets Mn12ac and Fe8. We determine the crystal field parameters with unprecedented accuracy and describe the temperature behavior of the transition intensities quantitatively. The influence of the molecular environment is discussed [1]. In Mn12ac, at elevated temperatures “homogeneous” relaxation due to thermal activation dominates the spin dynamics, while for T<2.5 K resonant quantum tunneling becomes important; here “inhomogeneous” relaxation and magnetic hole burning is observed. We have developed a model which allows to quantitatively describe all observed effects and to extract the quantum relaxation parameters, including the effective tunneling splitting and the spin-phonon relaxation rate [2].
[1] A. Mukhin et al., Phys. Rev. B 63, 214 411 (2001)
[2] M. Dressel et al., submitted to Phys. Rev. Lett.