Intersite Coulomb repulsion driven quadrupole instability and magnetic ordering in the orbital frustrated Ba₂MgReO₆

2023/03/07 by Xuanye Zhang, Zhang, Xuanye, Jinyu Zou +3
Physics and Astronomy · Materials Science · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Magnetic and transport properties of perovskites and related materials

paper · pdf · doi:10.48550/arxiv.2303.04010

Abstract

We develop an unrestricted Hartree-Fock mean-field method including Coulomb repulsion U, V and spin-orbital coupling λ self-consistently to investigate the mechanism of structural instability and magnetic ordering in Ba₂MgReO₆. A comprehensive quadrupole phase diagram versus U and V with λ=0.28eV is calculated. Our results demonstrate that the easy-plane anisotropy and the intersite Coulomb repulsion V must be considered to remove the orbital frustration. The increasing of V to >20meV would arrange quadrupole Q_x²-y² antiparallelly, accompanied with small parallel Q_3z²-r², and stabilize Ba₂MgReO₆ into the body-centered tetragonal structure. Such antiparallel Q_x²-y² provides a new mechanism of Dzyaloshinskii-Moriya interaction, and gives rise to the canted antiferromagnetic (CAF) state along [110] axis. Moreover, sizable octupoles such as O₂₁³¹, O₂₁³³, O₂₁³⁴ and O₂₁³⁶ are discovered for the first time in CAF state. Our study not only provides a comprehensive understanding of the experiment results in Ba₂MgReO₆, but also reveals some commonalities of 5d compounds.

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