1H and 39K spin–lattice relaxation, ionic motion and Raman processes in the proton conducting KHSeO 4 single crystal

Abstract

The spin–lattice relaxation rates of 1H and 39K nuclei in KHSeO 4 crystals were studied in the temperature range 160–400 K. The spin–lattice relaxation recovery of 1H nucleus in this crystal can be represented with a single exponential function, and the relaxation T 1 −1 curve of 1H can be represented with the Bloembergen–Purcell–Pound (BPP) function. The relaxation process of 39K with dominant quadrupole relaxation can be described by a linear combination of two exponential functions. T 1 −1 for the 39K nucleus was found to have a very strong temperature dependence, T 1 −1= βT 7. Rapid variations in relaxation rates are associated with critical fluctuations in the electronic spin system. The T 7 temperature dependence of the Raman relaxation rate is shown here to be due to phonon–magnon coupling.