Pb207spin-lattice relaxation in solidPbMoO4and

Peter A. Beckmann

¹

,

Shi Bai

²

,

Alexander J. Vega

³

et al.

Abstract

We have measured the 207 Pb nuclear spin-lattice relaxation rate R as a function of temperature T at two nuclear magnetic resonance frequencies 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 0 . Taken together with previous work in lead nitrate ͓Pb͑NO 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.

Spin-lattice relaxation of heavy spin-1/2 nuclei in diamagnetic solids: A Raman process mediated by spin-rotation interaction

“…This difference is entirely due to the different moments of inertia, as can be seen from the ⌫ coefficients, which are equal for these two molecules within the accuracy displayed in the table. Similarly, the value of C for 139 Sb in Sb 14 N differs from that in Sb 15 N by 5% but the two values of ⌫ differ by only 1%. In Fig.…”

“…We list results of spin-lattice relaxationtime measurements for all the spin-1/2 nuclei heavier than 103 Rh in Table I. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The unusual experimental results are that the spin-lattice relaxation rates 1 / T 1 of several of these nuclei simultaneously have three properties: First, the relaxation, in the absence of paramagnetic impurities and largescale molecular motion, is much more efficient than expected on the basis of experience with lighter nuclei in solids. The usual mechanisms ͑dipolar interactions, J couplings, chemical shifts, etc.͒ are unable to explain the efficient nuclear spin-lattice relaxation process observed.…”

“…[16][17][18][19] Recently, we have focused on spinlattice relaxation of 207 Pb and 111,113 Cd in ionic solids 4,5,14,15 and have begun projects for 119 Sn and 199 Hg. The study of heavy-nucleus spin-lattice relaxation is a field in its infancy.…”

Effects of Cd vacancies and unconventional spin dynamics in the Dirac semimetal Cd3As2

“…Raman nuclear spin-rotation mechanism 32,34 encountered here is related to the modulation of the angular velocity 29 (instead of the angular momentum of a molecule in liquid phase) and its strength is proportional to the interatomic distance (nuclear spin-spin dipolar interaction) 29,32,34 .…”

“…In particular, the T-dependence of 1/T1 reveals the observed power-law relaxation mechanism ( ; ∝ γ % ) to the lattice vibrations (phonons) 29,31 . In the case of Cd3As2, the calculated value [29][30][31][32] . We conclude that the spin-rotation-mediated relaxation pathway in 113 Cd of Cd3As2 is similarly effective as the one for 119 Sn (α-SnF2) but less effective than for 209 Pb (PbTiO3).…”