Externally controlled and switchable 2D electron gas at the Rashba interface between ferroelectrics and heavy $d$ metals

TL;DR

This paper demonstrates how ultrathin platinum and palladium layers on ferroelectric PbTiO3 can host switchable two-dimensional electron gases with tunable Rashba spin splitting, enabling control of spintronic properties via polarization reversal.

Contribution

It provides first-principles simulations showing the control of Rashba effects and electronic transport in 2D electron gases at ferroelectric-metal interfaces, highlighting their potential for spintronic devices.

Findings

Rashba splitting varies with overlayer material and thickness.

Resistance changes significantly upon polarization reversal.

Band structure and spin textures are tunable via ferroelectric polarization.

Abstract

Strong spin-orbit coupling in noncentrosymmetric materials and interfaces results in remarkable physical phenomena, such as nontrivial spin textures, which may exhibit Rashba, Dresselhaus, and other intricated configurations. This provides a promising basis for nonvolatile spintronic devices and further implications. Here, we simulate from first principles a two-dimensional electron gas in ultrathin platinum and palladium layers grown on ferroelectric PbTiO$_3$(001). The latter allows, in principle, to switch and control the spin-to-charge conversion by the polarization reversal. We show how the band structure and its Rashba splitting differ in the Pt and Pd overlayers and how these electronic features change with increasing the overlayer thickness and upon reversal of polarization. Besides, for both overlayers, we simulated their current-voltage ($I-V$) characteristics, the resistance of which upon the polarization reversal changes between 20% and several hundred percent. The reported findings can be used to model directly the Rashba-Edelstein effect.