Manipulation of Nanoscale Domain Switching Using an Electron Beam with Omnidirectional Electric Field Distribution

Reversible ferroelectric domain (FD) manipulation with a high spatial resolution is critical for memory storage devices based on thin film ferroelectric materials. FD can be manipulated using techniques that apply heat, mechanical stress, or electric bias. However, these techniques have some drawbacks. Here we propose to use an electron beam with an omnidirectional electric field as a tool for erasable stable ferroelectric nanodomain manipulation. Our results suggest that local accumulation of charges contributes to the local electric field that determines domain configurations.

Figure 1

(a) A dark-field TEM image and its corresponding diffraction pattern. The area that was later subjected to local $e$-beam illumination was extracted from the green box. The blue circle indicates the exact $e$-beam illumination area. The polarization of the white contrast domain ($\beta -$) is schematically drawn by red arrows. (b) After $e$-beam illumination, a newly formed $\beta +$ domain with dark contrast is seen and its corresponding polarization is shown at the bottom.

Figure 2

(a) A dark-field TEM image using the $000\overline{2}$ diffraction spot. (b) Domain configurations after exposing to the $e$ beam. The blue circle indicates the $e$-beam illumination area. Red and green dashed lines represent the domain boundaries before and after the illumination, respectively. (c) Domain configurations after shifting the $e$ beam to a new position. Green and purple dashed lines represent the domain boundaries before and after the illumination, respectively.

Figure 3

(a) A schematic showing the omnidirectional electric field ($E$) induced by $e$-beam illumination in a thin film specimen. The blue circle indicates the $e$ beam illuminated area and the letter “C” represents charges. (b)–(c) TEM (left) and HAADF-STEM (right) images showing polarization before and after $e$-beam irradiation. (d) Schematic drawings of electric fields generated by negative and positive charges. (e) A theoretical model for the electric field magnitude distribution. The areas where domain switching would occur are indicated with yellow shadow bounded by red and green boundary lines in (d) and (e).

Figure 4

(a)–(g) A series of dark-field images showing the domain evolution under $e$-beam illumination at $t=0$, 10, 30, 50, 100, 200, and 600 s, respectively. Blue circles represent the illumination area. The red-dashed curve includes the experimental converted $\alpha$- domain area. (h) Experimental $E_z$ versus $r$ plots at different illumination times and the corresponding fitting curves using Eq. (2). The inset shows the fitting curve to the experimental $E_z$ as a function of time.

Figure 5

(a) Initial domain configurations in four areas before $e$-beam illumination. (b) Letters U, S, Y, and D were written on the areas in (a) via $e$-beam illumination.