Rashba-Dresselhaus spin-splitting in the bulk ferroelectric oxide BiAlO$_3$

TL;DR

This study demonstrates that BiAlO$_3$ exhibits both ferroelectricity and Rashba-Dresselhaus spin-splitting effects, with potential for electric control of spin states, supported by first-principles calculations and effective model analysis.

Contribution

It is the first oxide shown to combine ferroelectricity with Rashba-Dresselhaus effects, analyzed through density-functional calculations and $k ext{ extperiodcentered}p$ modeling.

Findings

BiAlO$_3$ exhibits spin-splitting near the conduction band minimum.

Reversal of spin texture occurs with ferroelectric polarization switching.

Both tetragonal and rhombohedral phases show these effects.

Abstract

It has been recently suggested that the coexistence of ferroelectricity and Rashba-like spin-splitting effects due to spin-orbit coupling in a single material may allow for a non-volatile electric control of spin degrees of freedom. In the present work, we compared the structural and ferroelectric properties of tetragonal and rhombohedral phases of ferroelectric BiAlO$_3$ by means of density-functional calculations. In both phases, we carefully investigated Rashba and Dresselhaus effects, giving rise to spin-splitting in their bulk electronic structure, particularly near the conduction band minimum, supplementing our first-principles results with an effective $ k\cdot p$ model analysis. The full reversal of the spin texture with ferroelectric polarization switching was also predicted. BiAlO$_3$ can therefore be considered as the first known oxide to exhibit a coexistence of ferroelectricity and Rashba-Dresselhaus effects.