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TT: Tiefe Temperaturen

TT 25: Postersitzung III: Pinning und Vortexdynamik, Massive HTSL, Bandleiter, Transporteigenschaften in HTSL, SL dünner Filme, Elektronen und Phononen in HTSL, Tunneln, Borkarbide, Quantenphasen und Metall-Isolator-Überg
änge, Anwendungen, Sonstiges

TT 25.74: Poster

Thursday, March 29, 2001, 14:30–17:00, Rang S\ 3

Optical spectroscopy of the crystal field transitions in the molecular magnets Fe₈ and Mn₁₂ — •Boris Gorshunov¹, Martin Dressel¹, Krishnan Rajagopal¹, Alexander Mukhin², Dante Gatteschi³, and Claudio Sangregorio³ — ¹I.Physikalisches Institut, Universitaet Stuttgart, Germany — ²Institute of General Physics, Russian Academy of Sciences, Moscow, Russia — ³Dipartimento di Chimica, Universita di Firenze, Italy

Optical spectroscopic studies on the molecular cluster magnets Fe₈, Fe₈-perchlorate (Fe₈PCL) and Mn₁₂ have been performed at frequencies 1.5-33 cm⁻¹. Transitions inside the spin S=10 ground state split by the crystal field are observed; they exhibit a distinct temperature behavior of the resonance frequencies, linewidths, intensities, and are characterized by a Gaussian rather than a Lorentzian lineshape, originating from a random distribution of the internal dipolar magnetic fields. An excellent agreement of experimental findings and theoretical description is obtained. Several new absorption lines are discovered above 15 cm⁻¹ which could originate from electronic transitions between different multiplets or lattice vibration modes. Influence of external magnetic field up to 7 Tesla on the transitions is studied.