Multiferroic materials are attractive for controlling magnetic order using an electric field, a process that potentially requires very little energy. In the model multiferroic material, BiFeO3, antiferromagnetic order is coupled to ferroelectric order at room temperature. In BiFeO3 thin films, however, epitaxial strain typically induces multiple ferroelectric variants, complicating both the landscape of coupled antiferromagnetic textures and the electric field’s influence on these multiferroic domains. A key objective is to deterministically control the effect of the electric field on polar and antiferromagnetic textures.
In this study, we use vicinal SrTiO3 substrates to grow BiFeO3 thin films via pulsed laser deposition. By carefully selecting the vicinal crystal axis, mechanical strain stabilizes a single ferroelectric domain across the entire sample, which we visualize using near-field piezoresponse force microscopy (PFM). Using scanning NV-center magnetometry, we observed that the associated magnetic state corresponds to a single antiferromagnetic spin cycloid.
Upon applying an electric field, we observe that the polarization in these thin films always reverses in the same way—rotating by 180°—while remaining within the same ferroelastic domain. This deterministic control of polarization is accompanied by a change in the antiferromagnetic order, which shifts to a collinear antiferromagnetic state (see Figure), which is potentially altermagnetic. This work paves the way for the development of magnetoelectric memory devices.
This research was conducted in collaboration with the laboratoire Structures Propriétés et Modélisation des Solides (SPMS), the Luxembourg Institute of Science and Technology (LIST), the Laboratoire Charles Coulomb (L2C), the Laboratoire de Physique des Solides (LPS), the Service de Physique de l’Etat Condensé (SPEC) et the Synchrotron SOLEIL.
Reference:
Non-volatile electric-field toggling between antiferromagnetic states
- Abdelsamie, N. Rezi, A. Chaudron, O. Condurache, C.A.M. Scott, E. Wane, J.-D. You, X. Li, C. Carrétéro, F. Godel, R. Mattana, V. Jacques, M. Viret, A. Finco, B. Dkhil, J. Íñiguez-González, A. Gloter, N. Jaouen, J.-Y. Chauleau, K. Bouzehouane, S. Fusil, V. Garcia
