Nonvolatile Rashba Effect via Ferroelectric Switching in the GeSb/α-In ₂ Se ₃ Heterostructure: Implications for Spintronics and Spin-Caloritronics

Ferroelectric (FE) Rashba semiconductors represent a burgeoning class of multifunctional materials with immense potential for next-generation spintronic and spin-caloritronic applications. In this work, we present a comprehensive first-principles investigation of the GeSb/α-In2Se3 van der Waals (vdW) heterostructure, focusing on the interplay among FE polarization, interfacial charge transfer, and spin-dependent electronic properties. The intrinsic FE polarization of α-In2Se3 in the heterostructure enables reversible modulation of Rashba spin splitting (RSS) and spin transport behavior. Under upward polarization (P↑), RSS emerges at the Γ point of the conduction band with a large Rashba coefficient of 1.32 eV Å, displaying a conventional spin texture. Conversely, downward polarization (P↓) shifts the RSS to the valence band, yielding a Rashba coefficient of 0.93 eV Å with an unconventional spin texture. This polarization-dependent reconfiguration of the band structure is driven by interfacial charge redistribution, which amplifies the internal electric field and spin–orbit coupling effects. Moreover, both spin Hall conductivity and spin Nernst conductivity exhibit strong tunability with FE switching and Fermi level adjustment, enabling efficient control over spin transport phenomena. Our results reveal the GeSb/α-In2Se3 heterostructure as a promising candidate for multifunctional device applications, including nonvolatile memory, advanced logic circuits, spintronics, and spin-caloritronics.