Symmetry of ferroelectric switching and domain walls in hafnium dioxide

TL;DR

This paper investigates the symmetry and topology of ferroelectric switching paths and domain walls in hafnium dioxide, providing a comprehensive classification and understanding of its switching mechanisms.

Contribution

It introduces a topological symmetry perspective to classify and analyze ferroelectric switching paths and domain walls in HfO2, revealing anisotropic switching mechanisms.

Findings

Identified 4 low-barrier switching paths in HfO2.

Classified 93 irreducible domain wall configurations.

Discovered anisotropic switching behavior based on domain wall mobility.

Abstract

Hafnium dioxide (HfO2) is a promising ferroelectric (FE) material for achieving high-density nonvolatile memory and neuromorphic computing, due to its compatibility with the mainstream integrated circuit technology and the surprisingly enhanced ferroelectricity by reduced thickness. The FE switching dynamics is essential to the device performance, but the complexity of HfO2 atomic structure causes unknown of various FE switching paths and domain wall configurations. Here, we demonstrate that its low-barrier paths and domain walls can be comprehensively found and understood from a perspective of topological symmetry. By discussing pseudo-chirality and equivalent transformation relations in crystal with first principles and lattice modes, we classify and analyze 4 low-barrier FE switching paths and 93 irreducible topology domain wall configurations in HfO2. Anisotropic switching mechanism is found based on the mobility investigation for 12 types of 180{\deg} side domain walls. This methodology is expected to be generally applicable to displacive ferroelectrics with low unit cell point group symmetries, and lay a foundation for mechanism study of the switching dynamics.