Domain growth dynamics in (K, Na)NbO 3 ferroelectric thin films

Polarization Domain Dynamics of Barium Titanate Ultrathin Films Using Piezoresponse Force Microscopy.

“…This is observed using the PFM to scan over the thin film which measures and maps out the polarization perpendicular to the surface. However, the ferroelectric dipoles are not only observed to quickly align perpendicular to the surface directly below the hemisphere of the tip, but also slowly expand laterally to a region beyond several tip diameters [6][7][8][9][10][11][12][13][14][15] (Fig. 1b).…”

“…There have been several recent studies of ferroelectric polarization domain formation under an applied electric field [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] , many of which have focused on the application of piezoresponse force microscopy (PFM) to both form and probe polarization domains [6][7][8][9][10][11][12][13][14][15] . In the PFM technique, the tip of an atomic force microscope (AFM) makes contact with a thin film at a specific point and applies an electric potential across a thin film using the AFM tip as one electrode and the back side of the sample as the second electrode (Fig.…”

“…The electric field in the region just beneath the tip is nearly perpendicular to the thin film surface, except for fringing electric field effects. Under the force of the applied electric field, the ferroelectric dipoles align in a direction dependent on the field direction and crystal orientation, resulting in the formation of aligned dipoles directly under the AFM tip [6][7][8][9][10][11][12][13][14][15] . This is observed using the PFM to scan over the thin film which measures and maps out the polarization perpendicular to the surface.…”

“…1 and Eq. 2, has been investigated [6][7][8][9][10][11][12][13][14][15]23,24 by several investigators, the role of the thickness of the ferroelectric thin films, is not yet clear. This is evidenced by the fact that, very different models for the lateral spatial dependence of the electric field perpendicular to the surface, away from the AFM tip (Fig.…”

“…This is evidenced by the fact that, very different models for the lateral spatial dependence of the electric field perpendicular to the surface, away from the AFM tip (Fig. 1a) have been proposed to describe the lateral expansion of the domain wall, and these models vary on the role of the film thickness [6][7][8][9][10][11][12][13][14][15]25,26 . In this paper we : (a) demonstrate that the electric field due to an AFM tip, in a thin film, in a direction perpendicular to the surface, is produced by the cone of the tip rather than the field produced by the hemisphere of the tip, beginning at a lateral distance only about one tip diameter away from the tip (Fig.…”