Fe/GeTe(111) heterostructures as an avenue towards spintronics based on ferroelectric Rashba semiconductors

Abstract

By performing density functional theory (DFT) and Green's functions calculations, complemented by X-ray Photoemission Spectroscopy, we investigate the electronic structure of Fe/GeTe(111), a prototypical ferromagnetic/Rashba-ferroelectric interface. We reveal that such system exhibits several intriguing properties resulting from the complex interplay of exchange interaction, electric polarization and spin-orbit coupling. Despite a rather strong interfacial hybridization between Fe and GeTe bands, resulting in a complete suppression of the surface states of the latter, the bulk Rashba bands are hardly altered by the ferromagnetic overlayer. This could have a deep impact on spin dependent phenomena observed at this interface, such as spin-to-charge interconversion, which are likely to involve bulk rather than surface Rashba states.

Room-temperature ferroelectric switching of spin-to-charge conversion in germanium telluride

“…First-principles calculations are used to explore the origin of this phenomenon, and show that the inverse spin Hall effect has a major role in SCC. Notably, the SCC in Fe/GeTe is distinct from two-dimensional alternatives 10 in that it involves bulk bands rather than interface or surface Rashba states 18 . Our system has the potential to be monolithically integrated on silicon and could be of value in the development of beyond-CMOS applications such as spin transistors and spin interconnects through the substrate 19 .…”

Spin Hall effect in prototype Rashba ferroelectrics GeTe and SnTe

“…18 Importantly, spinto-charge conversion has been recently measured via spin pumping experiments in Fe/GeTe bilayers demonstrating high potential of such interfaces for multifunctional spintronics applications. 19,20 On the other hand, ferroelectric phase of SnTe (T C = 100 K) 21 has been known mainly from the theoretical side. 22 Although the intermediate topological phases predicted at the phase transition still await an experimental confirmation, even the room temperature cubic crystal is intriguing, as it represents a prototypical example of a topological crystalline insulator.…”

Room-temperature ferroelectric control of spin-to-charge conversion in GeTe

“…We stress however that IREE is a surface/interface effect, unlikely here due to the possible suppression of surface states of GeTe induced by the deposition of Fe 18 , while in our system a spin current can propagate within the semiconducting GeTe film, suggesting rather a bulk-like origin of the observed spin-to-charge conversion. Although we cannot completely rule out IREE, the quantitative arguments discussed below suggest a minor contribution of this phenomenon.…”

“…Finally, we employ first principles calculations to shed more light on the origin of the observed phenomenon and reveal a major role of the inverse spin Hall effect in the SCC mechanism. Importantly, the spin-to-charge conversion in Fe/GeTe involves the bulk bands rather than the usually studied interface or surface Rashba states 18 , thus distinguishing this system from 2D alternatives and opening the way to beyond-CMOS applications, with the monolithic integrability on silicon exploitable for the development of transistors as well as spin interconnects through the substrate 19 .…”