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Prog. Theor. Phys. Supplement No.145 (2002) pp. 357-369

The V₁₅ Molecule, a Multi-Spin Two-Level System: Adiabatic LZS Transition with or without Dissipation and Kramers Theorem

Bernard Barbara,¹ Irinel Chiorescu^1,* Wolfgang Wernsdorfer,¹ Hartmut Bogge² and Achim Muller²

¹Laboratoire de Magnetisme Louis Néel, CNRS, BP 166, 38042-Grenoble, France
²Fakultat fur Chemie, Universitat Bielefeld, D-33501 Bielefeld, Germany

(Received April 1, 2002)

Abstract:

The so-called V₁₅ compound, of formula K₆ [V₁₅ ^IVAs₆O₄₂ (H₂O)]8H₂O, is formed of 15 spins 1/2 antiferromagnetically coupled. The resultant spin is equal to 1/2. Contrary to what is expected at first sight, this half-integer spin is gapped. We show that this is a consequence of the multi-spin character of the molecule. Time reversal symmetry (Kramers theorem) is preserved due to the existence of a groundstate degeneracy larger than 2. Magnetization experiments have been performed at different temperatures, sweeping-field rates and couplings with the cryostat. Their interpretation in terms of the Landau-Zener-Stückelberg model gives evidence for adiabatic LZS spin reversal with and without dissipation.

URL : http://ptp.ipap.jp/link?PTPS/145/357/
DOI : 10.1143/PTPS.145.357

^*Present address: Delft University of Technology, Dept. of Applied Physics, 2628 CJ Delft, The Netherlands.

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Citing Article(s) :

1. ERROR : Mag:43, Vol:126, Page:
2. Progress of Theoretical Physics Vol. 109 No. 5 (2003) pp. 741-749 :

   Parity Effect in the Resonant Tunneling

   Seiji Miyashita, Keiji Saito and Hiroto Kobayashi

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