Author(s): Ross Richins
Mentor(s): Shao Qiu
Institution SUU
WTe₂, a two-dimensional (2D) van der Waals (vdW) material, has gained attention for its potential to exhibit out-of-plane ferroelectricity. However, as a semimetal, WTe₂ requires an insulating phase for polarization to be meaningful. In this study, we investigate the effects of mechanical strain on WTe₂ to induce a transition from semimetallic to insulating behavior, which is crucial for sustaining spontaneous polarization. Using density functional theory (DFT), we apply biaxial strain to the WTe₂ system, focusing on altering the lattice constants in both the a and b-axes. So far, our efforts in the bulk system have not successfully opened a band gap, a necessary condition for ferroelectric behavior. Without an insulating phase, studying meaningful polarization becomes challenging. To address this, we have shifted our focus to a bilayer WTe₂ system. Our ongoing work involves applying strain to this reduced system, with the hope of inducing a band gap. Achieving an insulating state in the bilayer system could pave the way for investigating out-of-plane polarization, as well as polarization switching mechanisms through interlayer sliding, which is characteristic of vdW materials. Our next steps involve continuing strain analysis in the bilayer system and performing Berry phase calculations to quantify polarization in the insulating phase. The ultimate goal is to identify conditions under which WTe₂ becomes ferroelectric, thereby advancing the potential for 2D ferroelectric materials in nanoscale electronic and memory devices.