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Phys. Rev. Lett. 97, 047203 (2006) [4 pages]

Neutron Spin-Echo Investigation of Slow Spin Dynamics in Kagomé-Bilayer Frustrated Magnets as Evidence for Phonon Assisted Relaxation in SrCr9xGa12-9xO19

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H. Mutka1,*, G. Ehlers1,†, C. Payen2, D. Bono3,‡, J. R. Stewart1, P. Fouquet1, P. Mendels3, J. Y. Mevellec2, N. Blanchard3, and G. Collin4
1Institut Laue-Langevin, Boîte Postale 156X, F-38042 Grenoble Cedex 9, France
2Institut des Matériaux Jean Rouxel, UMR 6502, Université de Nantes, Boîte Postale 32229, F-44322 Nantes Cedex 3, France
3Laboratoire de Physique des Solides, UMR 8502, Université Paris-Sud, 91405 Orsay, France
4Laboratoire Léon Brillouin, CE Saclay, CEA-CNRS, 91191 Gif-sur Yvette, France

Received 20 March 2006; published 28 July 2006

A neutron spin-echo investigation of the low temperature spin dynamics in two well-characterized kagomé bilayer compounds SrCr9xGa12-9xO19 (x=0.95, SCGO) and Ba2Sn2ZnCr7xGa10-7xO22 (x=0.97, BSZCGO) reveals two novel features. One is the slowing down of the relaxation rate without critical behavior at Tg, where a macroscopic spin-glass-like freezing occurs. The second is, in SCGO at 4 K (≈Tg)<T<7  K, the relaxation rate activation energy Ea=7±0.4  meV, equal to the energy of a phonon mode, pointing out the role of spin-lattice coupling.

© 2006 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.97.047203
DOI:
10.1103/PhysRevLett.97.047203
PACS:
75.50.Lk, 61.12.Ex, 75.40.Gb

*Electronic address: mutka@ill.fr

†Also at and present address: SNS Project, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.

‡Present address: Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504 2300 RA Leiden, The Netherlands.

 
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