Strain engineering of ferroelectric polarization and domain in the two-dimensional multiferroic semiconductor

Two-dimensional (2D) ferroelectricity has attracted great interest for its potential to develop various flexible and stretchable ultra-thin smart devices. The ultra-thin nature of 2D materials makes domain control very challenging, as an external electric field inevitably leads to leakage currents and even material breakdown. Therefore, it is highly desirable to explore more practical and feasible methods to control ferroelectric (FE) domains. In this work, based on the coupling between the ferroelasticity and ferroelectricity in 2D multiferroic materials, we propose a strategy to control the FE polarization direction and domain through the strain engineering. Taking beta '-In2Se3 as an example, we revealed the regulation mechanism of the uniaxial strain and shear strain on the ferroelasticity and ferroelectricity. We found that the polarization direction of FE beta '-In2Se3 is tunable by manipulating the strain, which demonstrates the feasibility to tailor the FE single domain as well as domain wall (DW) patterns. In addition, we also found that the angle between the stretching direction and the DW plays a crucial role in regulating the DW type, which provides an important reference for controlling DW. Therefore, the strain engineering not only provides an alternative solution for forming large-sized single domain FE materials, but also enable customized FE domain structures for DW electronics by ingeniously designing strain patterns.