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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 15: Multiferroics and Magnetoelectric Coupling (joint session MA/KFM)

KFM 15.5: Talk

Wednesday, March 20, 2024, 16:00–16:15, EB 407

Antimagnetoelectricy in multiferroic BiCoO₃ from first-principles — •Bogdan Guster¹, Maxime Braun^1,2, Houria Kabbour², and Eric Bousquet¹ — ¹Physique Théorique des Matériaux, QMAT, CESAM, Université de Liège, B-4000 Sart-Tilman, Belgium — ²Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181-UCCS-Unité de Catalyse et Chimie du Solide, F-59000 Lille, France

The lack of magnetoelectric response in a multiferroics is prompted by the magnetic space group symmetry. This is the case of BiCoO₃ where the C-AFM ground state prohibits the promotion of a magnetoelectric coupling. However, at the microscopic level, the local magnetoelectric coupling could exhibit non-zero responses for both spin and orbital components. Here we show from first-principles calculations that the amplitude of dynamical magnetic charges arising from both spin- and orbital-lattice coupling in the C-AFM phase of BiCoO₃ are large when compared to the paradigmatic Cr₂O₃. While globally the response is zero, we resolute that the pseudo-tensorial character of the dynamical magnetic charges manifests an alternating sign for atoms yet on the same Wyckoff position. Consequently, unlocking the C-AFM phase, one could potentially allow for a large magnetoelectric response. To prove this, we calculate the full magnetoelectric response in the ferromagnetic phase of BiCoO₃ and we find a colossal response of 1000 ps/m, among the largest reponses found so far in a single-crystal. We will discuss several strategies on how this large response could be released in some specific conditions and why the response is large.