Unit-cell-thick domain in free-standing quasi-two-dimensional ferroelectric material

Understanding the domain structure of two-dimensional materials is of paramount importance for the design of next generation microelectronic devices. Here, the authors employ a Dion--Jacobson layered oxide as a model system to study the ferroelectric domain structure with atomic scale analysis. They reveal the existence of a unit-cell-thick ferroelectric domain size as well as both 180\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{} domain walls in a free-standing ferroelectric oxide. This may suggest ways to achieve unit-cell-thick domain structures and shed light on promising material solutions for emerging nonvolatile high-density memories and synaptic devices.