Anomalous ¹⁴¹ Pr nuclear magnetic relaxation in PrF <inf>3</inf> Van Vleck paramagnet

Abstract

© Kazan Federal University (KFU). The magnetic nuclear spin-lattice relaxation has been studied in PrF 3 . It was found that 141 Pr spin-lattice relaxation rate is untypically high for the Van Vleck insulator. According to all existing experimental data the only relaxation channel for enhanced nuclear moments at low temperatures is interaction with paramagnetic impurities and typical nuclear relaxation rate in rare earth Van Vleck paramagnets at liquid helium temperatures is 1 s -1 . The measured value is 100 s -1 . At the assumption that relaxation is caused by the strong 4f-4f cooperative interaction mediated by phonons [1], we measured 141 Pr relaxation rates in a number of Pr x La 1 - x F 3 samples and found that in diluted samples relaxation slows down to the usual for insulators values.