Theoretical study of two-step polarization switching in BiFeO₃

BiFeO₃ (BFO) is a multiferroic material in which electric polarization, P, coexists with weak magnetization at room temperature. An electric-field induced reversal of the magnetization occurs in BFO as a result of a two-step P switching process (109^o out-of-plane then 71^o in-plane P rotation or vice versa) [1]. However, the origin of this is still not understood, which hampers its optimization necessary for the development of magnetoelectric memory and logic devices [2].

We combine density functional theory (DFT) and Landau-Khalatnikov (LK) simulations to elucidate the origin of the two-step P switching in BFO and to study its dynamics. First, we introduce the BFO thermodynamic potential and compute its parameters using DFT. Then, we extend our model by introducing the constraints that account for the presence of the substrate and multidomain configuration observed experimentally. Finally, we run LK dynamical simulations to investigate the role of these constraints on the two-step P switching, and to identify potential ways to optimize it.

[1] Heron J. et al., Nature 516, 370 (2014).

[2] Manipatruni S. et al, Nature 565, 35 (2019).