Simulation of the Magnetization Dynamics of a Single Domain BiFeO$_3$ Thin Film

TL;DR

This paper models the coupled polarization and antiferromagnetic Neel vector dynamics in a single-domain BiFeO$_3$ thin film, demonstrating 180-degree Neel vector switching within 30 ps driven by polarization reversal.

Contribution

It introduces a theoretical simulation combining Landau-Khalatnikov and Landau-Lifshitz-Gilbert equations to study magnetization dynamics in BiFeO$_3$ thin films, revealing rapid Neel vector switching.

Findings

Neel vector can be switched by 180 degrees during polarization reversal.

Switching time of the Neel vector can be as short as 30 ps.

Simulation results agree with ab initio and Landau-Ginzburg calculations.

Abstract

The switching dynamics of a single-domain BiFeO$_3$ thin films is investigated through combining the dynamics of polarization and Neel vector. The evolution of the ferroelectric polarization is described by the Landau-Khalatnikov (LK) equation, and the Landau-Lifshitz-Gilbert (LLG) equations for spins in two sublattices to model the time evolution of the antiferromagnetic order (Neel vector) in a G-type antiferromagnet. This work theoretically demonstrates that due to the rotation of the magnetic hard axis following the polarization reversal, the Neel vector can be switched by 180 degrees, while the weak magnetization can remain unchanged. The simulation results are consistent with the ab initio calculation, where the Neel vector rotates during polarization rotation, and also match our calculation of the dynamics of order parameter using Landau-Ginzburg theory. We also find that the switching time of the Neel vector is determined by the speed polarization switching and is predicted to be as short as 30 ps.