Pseudo-proper ferroelectricity in thin films

TL;DR

This paper investigates pseudo-proper ferroelectricity in thin films, revealing its robustness against depolarizing fields, the stability of single-domain states with metallic electrodes, and the emergence of unique multi-domain states in ultrathin films.

Contribution

It demonstrates that pseudo-proper ferroelectrics are more resistant to depolarizing effects and introduces new multi-domain regimes influenced by boundary conditions.

Findings

Pseudo-proper ferroelectricity is more resilient to depolarizing fields.

Single-domain states can be maintained with metallic electrodes.

Unusual multi-domain states occur in ultrathin films without screening.

Abstract

We study ferroelectricity in thin films of pseudo-proper ferroelectrics such as the so-called spiral multiferroics. We find that this type of ferroelectricity stands better against depolarizing fields than conventional one. Its single-domain state can be easily preserved by metallic electrodes even in ultrathin films. In fact, single-domain ferroelectricty can be generated as a metastable state in the absence of electrodes. We also find a new regime of small thickness where unscreened films develop unusual multi-domain states with properties determined by non-electrostatic boundary conditions.