Low-temperature characterization of domain wall dynamics and electrical conduction in a proton-irradiated K(H_0.21D_0.79)₂PO₄ system

We investigated the longitudinal electrical conductivity associated with the domain-wall dynamics in proton-irradiated K(H_0.21D_0.79)₂PO₄ single crystals a temperatures below room temperature. Frequency-dependent longitudinal dielectric-loss measurements allowed us to investigate the changes in the domain-wall dynamics of the proton-irradiated crystal with a ferroelectric phase-transition temperature increase of 8 K. Using the Vogel-Fulcher function, we found that proton irradiation produced a slight increase in the activation energy of domain freezing. The temperature dependence of the power-law exponent n in frequency-dependent electrical conductivity in proton-conducting systems decreased at temperatures near the phase-transition temperature T_c2. In addition, the temperature dependence of the electrical conductivity shifted to higher temperatures because of the increased phase-transition temperature arising from the proton irradiation.