Reversible spin texture in ferroelectric HfO2

TL;DR

This study reveals that ferroelectric HfO2 exhibits reversible spin textures driven by spin-orbit coupling, with potential applications in spintronics due to its large Dresselhaus constant and controllable spin configurations.

Contribution

The paper demonstrates, through theoretical modeling, the presence of reversible chiral spin textures in ferroelectric HfO2 and characterizes their origin via Rashba and Dresselhaus effects.

Findings

Rashba spin texture dominates near the valence band maximum.

Dresselhaus spin texture dominates near the conduction band minimum.

Large Dresselhaus constant enables spintronic applications.

Abstract

Spin-orbit coupling effects occurring in non-centrosymmetric materials are known to be responsible for non-trivial spin configurations and a number of emergent physical phenomena. Ferroelectric materials may be especially interesting in this regard due to reversible spontaneous polarization making possible for a non-volatile electrical control of the spin degrees of freedom. Here, we explore a technologically relevant oxide material, HfO2, which has been shown to exhibit robust ferroelectricity in a non-centrosymmetric orthorhombic phase. Using theoretical modelling based on density-functional theory, we investigate the spin-dependent electronic structure of the ferroelectric HfO2 and demonstrate the appearance of chiral spin textures driven by spin-orbit coupling. We analyze these spin configurations in terms of the Rashba and Dresselhaus effects within the k.p Hamiltonian model and find that the Rashba-type spin texture dominates around the valence band maximum, while the Dresselhaus-type spin texture prevails around the conduction band minimum. The latter is characterized by a very large Dresselhaus constant {\alpha}D = 0.578 eV {\AA}, which allows using this material as a tunnel barrier to produce tunneling anomalous and spin Hall effects that are reversible by ferroelectric polarization.