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MA: Fachverband Magnetismus

MA 14: Focus Session: Frustrated Magnetism and Local Order (joint session MA/TT)

MA 14.5: Talk

Tuesday, March 19, 2024, 11:15–11:30, H 1058

Multipolar order in the 5d double perovskite Ba₂MgReO₆ from DFT+DMFT — Maximilian E. Merkel and •Claude Ederer — Materials Theory, ETH Zürich, Switzerland

We establish the effect of electronic correlations and strong-spin-orbit coupling on the emergence of the insulating state and the quadrupolar order in the magnetically frustrated 5d double perovskite Ba₂MgReO₆ (BMRO). BMRO exhibits a tetragonally distorted paramagnetic phase below T_q ∼ 33 K and a non-collinear magnetically ordered state below T_m ∼ 18 K. Using density functional theory in combination with dynamical mean-field theory (DFT+DMFT), we demonstrate that BMRO should be classified as a normal Mott insulator where the spin-orbit coupling is not crucial for the formation of the insulating state. Our calculations further reveal a subtle interplay between the electronic quadrupolar order and the Jahn-Teller distortion, where the primary instability is of electronic origin but the coupling to the structural distortion determines the specific character of the emerging order.

Keywords: double perovskites; strong spin-orbit coupling; mutipolar order; DFT+DMFT