Structural and electronic phenomena at oxyfluoride KTaO$_3$/K$M$F$_3$ ($M$ = Zn and Ni) superlattices: Rashba splitting and 2DEG

TL;DR

This paper uses first-principles calculations to analyze the structural and electronic properties of KTaO3/KMF3 superlattices, revealing 2DEG/2DHG formation and significant Rashba spin-splitting at interfaces.

Contribution

It provides a theoretical analysis of oxide/fluoride superlattices, highlighting the role of phonon dynamics and discovering notable Rashba effects not seen in oxide/oxide systems.

Findings

Formation of 2DEG and 2DHG as a function of layer thickness

Significant Rashba spin-splitting at interfaces

Phonon dynamics influence electronic properties

Abstract

Here, we present the theoretical analysis of the structural and electronic degrees of freedom of two different oxide/fluoride perovskite superlattices, KTaO$_3$/KZnF$_3$ and KTaO$_3$/KNiF$_3$. Using first-principles calculations, we found the appearance of a two-dimensional electron, 2DEG, and hole, 2DHG, gases as a function of the number of layers of the different pristine materials. We demonstrate that the phonon-dynamics at the KTO/K$M$F superlattices play a crucial role in the appearance of these effects. Additionally, our results reveal a rather sizeable Rashba-type spin-splitting at these interfaces in comparison to another oxide/oxide counterparts.