Intersite Coulomb repulsion driven quadrupole instability and magnetic ordering in the orbital frustrated Ba$_2$MgReO$_6$

Xuanye Zhang; Jinyu Zou; Gang Xu

doi:10.1088/0256-307X/42/7/070703

paper

Intersite Coulomb repulsion driven quadrupole instability and magnetic ordering in the orbital frustrated Ba $_{2}$ MgReO $_{6}$

arXiv:2303.04010 · doi:10.1088/0256-307X/42/7/070703

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 Ba $_{2}$ MgReO $_{6}$ . 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 $Q_{x^{2} - y^{2}}$ antiparallelly, accompanied with small parallel $Q_{3 z^{2} - r^{2}}$ , and stabilize Ba $_{2}$ MgReO $_{6}$ into the body-centered tetragonal structure. Such antiparallel $Q_{x^{2} - y^{2}}$ 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 $O_{21}^{31}$ , $O_{21}^{33}$ , $O_{21}^{34}$ and $O_{21}^{36}$ are discovered for the first time in CAF state. Our study not only provides a comprehensive understanding of the experiment results in Ba $_{2}$ MgReO $_{6}$ , but also reveals some commonalities of 5d compounds.

Intersite Coulomb repulsion driven quadrupole instability and magnetic ordering in the orbital frustrated Ba2​MgReO6​

Abstract

References in corpus (13)

Intersite Coulomb repulsion driven quadrupole instability and magnetic ordering in the orbital frustrated Ba $_{2}$ MgReO $_{6}$