Electron spin-lattice relaxation of Yb3+ and Gd3+ ions in glasses |
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Authors: | D Vergnoux P K Zinsou M Zaripov G Ablart J Pescia S K Misra R Rakhmatullin S Orlinskii |
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Institution: | 1. Laboratoire de Magnétisme et d’Electronique Quantique (LMEQ), Université Paul Sabatier, Toulouse Cedex, France 2. Physics Department, Concordia University, 1455 de Maisonneuve Boulevard West, H3G 1M8, Montreal, (Quebec), Canada 3. Kazan State University, Kazan, Tatarstan, Russian Federation
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Abstract: | The electron spin-lattice relaxation rate (T 1 ?1) was measured in two glass samples: (i) a phosphate glass doped with 1 wt% Yb2O3 and (ii) a Li2Si4O9 glass sample doped with 0.2 wt% Gd2O3. In the Yb3+-doped glass sample,T 1 was measured by an electron-spin-echo technique from 4.2 to 6 K, by the modulation method from 10 to 26 K and by the EPR linewidth from 30 to 100 K. It was found thatT 1 ?1 αT n withn=9 in the range 4.2–6 K.n decreased gradually as the temperature was increased and tended towards 2 above 40 K. Over the entire temperature range 4.2–100 K,T 1 ?1 was fitted toAT+BT 9 J 8 (Θ D/T) (whereA andB are two temperature-independent constants,J 8 is the well-known Van Vleck integral andΘ D is the Debye temperature). The value ofΘ D (=46.3±0.9 K) so determined is in good agreement with that of Stevens and Stapleton from theirT 1 measurements in the range 1.5 to 7 K. In the Gd3+-doped glass, it was observed thatT 1 ?1 αT over the range 50–150 K. The data for Ye3+-doped glass sample were accounted for by assuming that the phonon modulation of the ligand field is the dominant mechanism, associated with a low Debye temperature in accordance with the published data obtained by using other techniques to study lattice dynamics. On the other hand, the data on the Gd3+-doped glass sample were explained to be predominantly due to a mechanism involving Two-Level-Systems (TLS) |
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