We report the observation of the effect of the quantum tunneling of the magnetization in the molecular nanomagnet [Fe8(N3C 6H15)6O2(OH)12]· [Br8·9H2O] (in short, Fe8) on the proton spin-lattice relaxation rates (T1-1) measured in single crystal Fe8 at 1.5 K. When the external field is applied parallel to the magnetic easy axis of the molecular nanomagnet, T 1-1 decreases monotonically, a behavior well explained in terms of the magnetization fluctuations due to spin-phonon interaction. On the other hand, a peak of T1-1 is observed as a function of transverse field for a value of H in the range 2.5-3.5 T. The position and shape of the peak depend upon the orientation of the field in the hard plane and the peak disappears as soon as a small out-of-plane magnetic-field component is introduced by misaligning the crystal. The experimental observations can be explained by considering the effect of the transverse field on the tunneling splitting whereby the peak of T1-1 is a direct consequence of the matching condition of the incoherent tunneling probability with the proton Larmor frequency.

Proton spin-lattice relaxation induced by quantum tunneling of the magnetization in the molecular nanomagnet Fe8 / Y. Furukawa, K. Aizawa, K. Kumagai, R. Ullu, A. Lascialfari, F. Borsa. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 69:1(2004), pp. 014405.014405-014405.144055.

Proton spin-lattice relaxation induced by quantum tunneling of the magnetization in the molecular nanomagnet Fe8

A. Lascialfari
Penultimo
;
2004

Abstract

We report the observation of the effect of the quantum tunneling of the magnetization in the molecular nanomagnet [Fe8(N3C 6H15)6O2(OH)12]· [Br8·9H2O] (in short, Fe8) on the proton spin-lattice relaxation rates (T1-1) measured in single crystal Fe8 at 1.5 K. When the external field is applied parallel to the magnetic easy axis of the molecular nanomagnet, T 1-1 decreases monotonically, a behavior well explained in terms of the magnetization fluctuations due to spin-phonon interaction. On the other hand, a peak of T1-1 is observed as a function of transverse field for a value of H in the range 2.5-3.5 T. The position and shape of the peak depend upon the orientation of the field in the hard plane and the peak disappears as soon as a small out-of-plane magnetic-field component is introduced by misaligning the crystal. The experimental observations can be explained by considering the effect of the transverse field on the tunneling splitting whereby the peak of T1-1 is a direct consequence of the matching condition of the incoherent tunneling probability with the proton Larmor frequency.
Settore FIS/03 - Fisica della Materia
Settore FIS/01 - Fisica Sperimentale
2004
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/145372
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