Dynamic Jahn-Teller effect in the strong spin-orbit coupling regime

Ivica Živković; Jian-Rui Soh; Oleg Malanyuk; Ravi Yadav; Federico Pisani; Aria M Tehrani; Davor Tolj; Jana Pasztorova; Daigorou Hirai; Yuan Wei; Wenliang Zhang; Carlos Galdino; Tianlun Yu; Kenji Ishii; Albin Demuer; Oleg V Yazyev; Thorsten Schmitt; Henrik M Rønnow

doi:10.1038/s41467-024-52935-w

Dynamic Jahn-Teller effect in the strong spin-orbit coupling regime

Nat Commun. 2024 Oct 4;15(1):8587. doi: 10.1038/s41467-024-52935-w.

Authors

Ivica Živković¹, Jian-Rui Soh², Oleg Malanyuk², Ravi Yadav², Federico Pisani², Aria M Tehrani³, Davor Tolj², Jana Pasztorova², Daigorou Hirai⁴, Yuan Wei⁵, Wenliang Zhang⁵, Carlos Galdino⁵, Tianlun Yu⁵, Kenji Ishii⁶, Albin Demuer⁷, Oleg V Yazyev⁸, Thorsten Schmitt⁵, Henrik M Rønnow²

Affiliations

¹ Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. [email protected].
² Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
³ Department of Materials, ETH Zurich, Zurich, Switzerland.
⁴ Department of Applied Physics, Nagoya University, Nagoya, Japan.
⁵ Paul Scherrer Institute, Villigen PSI, Switzerland.
⁶ Synchrotron Radiation Research Center, National Institutes for Quantum Science and Technology, Sayo, Hyogo, Japan.
⁷ Université Grenoble Alpes, INSA Toulouse, Université Toulouse Paul Sabatier, CNRS, LNCMI, Grenoble, France.
⁸ Chair of Computational Condensed Matter Physics, Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

Abstract

Exotic quantum phases, arising from a complex interplay of charge, spin, lattice and orbital degrees of freedom, are of immense interest to a wide research community. A well-known example of such an entangled behavior is the Jahn-Teller effect, where the lifting of orbital degeneracy proceeds through lattice distortions. Here we demonstrate that a highly-symmetrical 5d¹ double perovskite Ba₂MgReO₆, comprising a 3D array of isolated ReO₆ octahedra, represents a rare example of a dynamic Jahn-Teller system in the strong spin-orbit coupling regime. Thermodynamic and resonant inelastic x-ray scattering experiments, supported by quantum chemistry calculations, undoubtedly show that the Jahn-Teller instability leads to a ground-state doublet, resolving a long-standing puzzle in this family of compounds. The dynamic state of ReO₆ octahedra persists down to the lowest temperatures, where a multipolar order sets in, allowing for investigations of the interplay between a dynamic JT effect and strongly correlated electron behavior.