Issue Eur. Phys. J. B Volume 66, Number 2, November II 2008 Page(s) 155 - 163 Section Solid State and Materials DOI 10.1140/epjb/e2008-00411-7 Published online 14 November 2008

Eur. Phys. J. B 66, 155-163 (2008)
DOI: 10.1140/epjb/e2008-00411-7

¹⁹F nuclear spin relaxation and spin diffusion effects in the single-ion magnet LiYF₄:Ho³⁺

B.Z. Malkin¹, M.V. Vanyunin¹, M.J. Graf^{2, 3}, J. Lago³, F. Borsa³, A. Lascialfari^{3, 4}, A.M. Tkachuk⁵ and B. Barbara<sup>6

1</sup>  Physics Department, Kazan State University, Kazan 420008, Russian Federation
²  Department of Physics, Boston College, Chestnut Hill, MA 02467, USA
³  Department of Physics “A. Volta”, CNR-INFM Unit and CNISM Unit, Pavia 27100, and S3-CNR-INFM, Modena, Italy
⁴  Institute of General Physiology and Biological Chemistry, University of Milano, 20134 Milano, Italy
⁵  St. Petersburg State University of Information Technology, Mechanics and Optics, 199034, St. Petersburg, Russian Federation
⁶  Institut Néel, Département Nanosciences, CNRS, 38042 Grenoble Cedex 09, France

boris.malkin@ksu.ru

Received 9 July 2008 / Received in final form 15 August 2008 / Published online 14 November 2008

Abstract
Temperature and magnetic field dependences of the ¹⁹F nuclear spin-lattice relaxation in a single crystal of LiYF₄ doped with holmium are described by an approach based on a detailed consideration of the magnetic dipole-dipole interactions between nuclei and impurity paramagnetic ions and nuclear spin diffusion processes. The observed non-exponential long time recovery of the nuclear magnetization after saturation at intermediate temperatures is in agreement with predictions of the spin-diffusion theory in a case of the diffusion limited relaxation. At avoided level crossings in the spectrum of electron-nuclear states of Ho^{3 +} ions, rates of nuclear spin-lattice relaxation increase due to quasi-resonant energy exchange between nuclei and paramagnetic ions in contrast to the predominant role played by electronic cross-relaxation processes in the low-frequency ac-susceptibility.

PACS
76.60.-k - Nuclear magnetic resonance and relaxation.
75.40.Gb - Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.).
76.30.Kg - Rare-earth ions and impurities.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2008

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