Ferroelectric-Specific Stark Effect in Stoichiometric LiNbO3: Fe at Room Temperature

By means of EPR spectroscopy of LiNbΟ 3 :Fe at room temperature (RT) it is shown that the Stark effect in ferroelectric crystals can be different from that observed in other materials. Novel properties appear when an external E field reverses the direction of the spontaneous polarization, the direction of the linear Stark shift stays the same with a reversal of the E field. The corresponding spectral line shifts can occur over a long time scale (hours). These properties seem to be a general feature of the Stark effect in ferroelectric crystals when the external E field exceeds the coercive field.