Theoretical Design of Mono-Elemental Ferroelectricity with Tunable Spin Textures in Bilayer Tellurium

Abstract: 2D Ferroelectricity with switchable electric polarization has drawn widespread attention in condensed matter physics due to its crucial applications in non-volatile memory and ferroelectric spin devices. Despite recent progress in 2D ferroelectric, achieving the mono-elemental ferroelectricity still remains a great challenge because most nonmetallic mono-elemental materials are stabilized in nonpolar crystal structures. In this work, we theoretically designed mono-elemental ferroelectricity with tunable and significant spin textures in bilayer tellurium (BL-Te). Comprehensive quantitative polarization calculations demonstrate that asymmetric stacking in BL-Te can generate out-of-plane (OOP) polarization with a magnitude of 0.78 pC/m. This polarization stems from distinguishing interlayer and intra-layer 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 broaden the category of 2D mono-elemental ferroelectric but also offer a new platform for multifunctional nanodevices.