Charged domain walls and crystallographic microstructures in hybrid improper ferroelectric Ca${}_{3-x}$Sr${}_x$Ti${}_2$O${}_7$

Abstract

The charged domain walls in ferroelectric materials exhibit intriguing physical properties. We examine herein the charged-domain-wall structures in Ca${}_{3-x}$Sr${}_x$Ti${}_2$O${}_7$ using transmission electron microscopy. When viewed along the [001] axis, the wavy charged domain walls are observed over a wide range ($>$5 $\mu$m). In contrast, short charged-domain-wall fragments (from 10 to 200 nm long) occur because they are intercepted and truncated by the conventional 180${}^{°}$ domain walls. These results reveal the unusual charged domain structures in Ca${}_{3-x}$Sr${}_x$Ti${}_2$O${}_7$ and will be useful for understanding their formation process.

18 pages, 6 figures