Physical Review B
We have measured the (207)Pb nuclear spin-lattice relaxation rate R as a function of temperature T at two nuclear magnetic resonance frequencies omega(0) in the ionic solids lead molybdate (PbMoO(4)) and lead chloride (PbCl(2)). R is unexpectedly large, proportional to T(2), and independent of omega(0). Taken together with previous work in lead nitrate [Pb(NO(3))(2)], these results show that the relaxation does not depend on the nature or rotational motion of the counterion, particularly since the counterion in lead chloride is a single chlorine atom. The theory that explains the observed relaxation rate is reviewed. A second-order Raman process dominates the observed relaxation process. It involves the modulation of the spin-rotation interaction by the lattice vibrations.
© 2006 by the American Physical Society. The publisher's version of the article can be found at http://link.aps.org/doi/10.1103/PhysRevB.74.214421.
P.A. Beckmann, S. Bai, A. Vega, and C. Dybowski, Phys. Rev. B 74, 214421 (2006).