As75 Electric-Field-Gradient Fluctuations in KH2PO4-Type Ferroelectrics

Abstract

The electric-field-gradient tensor fluctuations at the ${\mathrm{As}}^{75}$ site in ferroelectric Rb${\mathrm{H}}_2$As${\mathrm{O}}_4$, Rb${\mathrm{D}}_2$As${\mathrm{O}}_4$, and K${\mathrm{H}}_2$As${\mathrm{O}}_4$ have been studied as a function of temperature and applied electric field. The measurements allow a direct determination of the Slater short-range energy parameter $\epsilon$ and provide a test of the nature of the ferroelectric-mode-type elementary excitations.