Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 4: Solids at Low Temperature - Materials

TT 4.3: Vortrag

Montag, 26. März 2007, 12:00–12:15, H18

Europium Tunneling in Eu₈Ga₁₆Ge₃₀ — •Raphaël P. Hermann — Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich ^* — Dept of Physics, B5, Université de Liège, B-4000 Sart-Tilman, Belgium — Dept of Materials Science and Engineering, The University of Tennesee, Knoxville, Tennessee, 37996-2200, USA

We report on Mössbauer spectral and microwave absorption experiments that reveal the atomic tunneling of Eu in the ferromagnetic phase of the Eu₈Ga₁₆Ge₃₀ clathrate[1]. Single crystal neutron diffraction had revealed that Eu reside off-center in the clathrate cages[2] and a signature of the tunneling was found in elastic constant measurements[3]. Our measurements reveal the ground state tunneling of 75% of the Eu with a frequency of ∼450 MHz in good agreement with the expected frequency for an isolated tunneling atom in a double well potential. The presence of such well defined ionic tunneling in a crystalline solid may open the route to solid-state technological applications of the associated Rabi oscillations.

[1] Hermann R. P. et al., Phys. Rev. Lett. 97, 017401 (2006). [2] Sales B. C. et al., Phys. Rev. B 63, 245113 (2001). [3] Zerec I. et al., Phys. Rev. Lett. 92, 185502 (2004).

^* Current address