Anomalous domains formed under AFM-TIP voltages in Sr_(0.61)Ba_(0.39)Nb_2O_6 crystals and their suppression

摘要

Submicro- and nanosized domain patterns are demanded by various applications. The most attractive method for fabrication of structures of these scales is the domain writing by an AFM-tip voltage U_(tip). The use of this method is limited by the appearance of so-called anomalous domains, in which a small area under the tip is polarized oppositely to the poling field. We present the studies of anomalous domains in zero-field cooled (ZFC) and field cooled Sr_(0.61)Ba_(0.39)Nb_2O_6 crystals. A correlation between the spatial distribution of the domain shape and the bias U_b of local hysteresis loops was found in ZFC crystals, namely, in the points with a larger U_b the anomalous domains appeared at higher U_(tip). Based on this correlation, we managed to prevent the formation of anomalous domains by a strong preliminary poling of the crystal resulting in an essential increase in U_b all over the bulk. The dependences of the domain diameter D on U_(tip) and the exposure time t_p are described by the unique linear and power D ～ t_p~k functions, respectively. These dependences are not affected by the appearance of an anomalous region growing with U_(tip) and t_p.