Theoretical design of monoelemental ferroelectricity with tunable spin textures in bilayer tellurium

Two-dimensional (2D) ferroelectricity with switchable electric polarization has drawn widespread attention in condensed matter physics due to its crucial applications in nonvolatile memory and ferroelectric spin devices. Despite recent progress in 2D ferroelectricity, achieving monoelemental (ME) ferroelectricity still remains a great challenge because most nonmetallic ME materials are stabilized in nonpolar crystal structures. In this work, we theoretically designed ME ferroelectricity with tunable and significant spin textures in bilayer tellurium (BL-Te). Comprehensive polarization calculations demonstrate that asymmetric stacking in BL-Te can generate out-of-plane (OOP) polarization with a magnitude of 0.49 pC/m. This polarization stems from distinguishing interlayer and intralayer contributions. Moreover, these stacked BL-Te, characterized by significant spin-orbit coupling, serve as an ideal platform for investigating both conventional spin polarization and layer-dependent/hidden spin polarization through ferroelectric reversion. Our work not only broadens the family of 2D ME ferroelectrics but also offers a new platform for multifunctional nanodevices.