Domain Switching in Irradiated Ferroelectric KH2PO4Observed by Electron Spin Resonance

The first direct observation of domain switching in radiation damaged ferroelectric K${\mathrm{H}}_2$P${\mathrm{O}}_4$ using electron spin resonance is reported. This switching is demonstrated by the observation of a reversal in orientation for the · OP${\mathrm{O}}_3$ ${\mathrm{H}}^{-}$ free-radical ions during polarization of the damaged crystal by an electric field. The reversal is accomplished by an intramolecular charge transfer which permits reversal of the damage sites on the microscopic level.