Orbital and spin order in spin-orbit coupled $d^1$ and $d^2$ double perovskites

Abstract

We consider strongly spin-orbit coupled double perovskites A${}_2$BB'O${}_6$ with B' magnetic ions in either $d^1$ or $d^2$ electronic configuration and non-magnetic B ions. We provide insights into several experimental puzzles, such as the predominance of ferromagnetism in $d^1$ versus antiferromagnetism in $d^2$ systems, the appearance of negative Curie-Weiss temperatures for ferromagnetic materials, and the size of effective magnetic moments. We develop and solve a microscopic model with both spin and orbital degrees of freedom within the Mott insulating regime at finite temperature using mean field theory. The interplay between anisotropic orbital degrees of freedom and spin-orbit coupling results in complex ground states in both $d^1$ and $d^2$ systems. We show that the ordering of orbital degrees of freedom in $d^1$ systems results in coplanar canted ferromagnetic and 4-sublattice antiferromagnetic structures. In $d^2$ systems we find additional colinear antiferromagnetic and ferromagnetic phases not appearing in $d^1$ systems. At finite temperatures, we find that orbital ordering driven by both superexchange and Coulomb interactions may occur at much higher temperatures compared to magnetic order and leads to distinct deviations from Curie-Weiss law.

12 pages, 4 figures

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Cited by in corpus (23)

• Dynamic Jahn-Teller effect in the strong spin-orbit coupling regime
• Dynamics of a j=3/2 quantum spin liquid
• Phase transition in the 5d1 double perovskite Ba2CaReO6 induced by high magnetic field
• Probing octupolar hidden order via Janus impurities
• Octupolar order and Ising quantum criticality tuned by strain and dimensionality: Application to $d$-orbital Mott insulators
• Vibronic order and emergent magnetism in cubic $d^1$ double perovskites
• Hidden orders in spin-orbit entangled correlated insulators
• Signatures of hidden octupolar order from nonlinear Hall effects
• Quadrupole partial orders and triple-$q$ states on the face-centered cubic lattice
• Interplay of superexchange and vibronic effects in the hidden order of Ba${}_2$MgReO${}_6$ from first principles
• Effects of charge doping on Mott insulator with strong spin-orbit coupling, Ba${}_2$NaOsO${}_6$
• Exploring energy landscapes of charge multipoles using constrained density functional theory
• Spin-orbit-entangled electronic structure of Ba${}_2$CaOsO${}_6$ studied by O $K$-edge resonant inelastic X-ray scattering
• Dynamic Jahn-Teller Phenomena in Heavy Transition Metal Compounds
• Electronic origin of ferroic quadrupole moment under antiferroic quadrupole orders and finite magnetic moment in $J_{\mathrm{eff}}=3/2$ systems
• Fate of multipolar physics in $5d^2$ double perovskites
• Chemical Pressure Tuning of Multipolar and Magnetic Orders in Ba${}_2$(Cd${}_{1-x}$Ca${}_x$)ReO${}_6$ Double Perovskites
• Dipolar and quadrupolar correlations in the $5d^2$ Re-based double perovskites Ba${}_2$YReO${}_6$ and Ba${}_2$ScReO${}_6$
• Magnetic behavior of the $5d^1$ Re-based double perovskite Sr${}_2$ZnReO${}_6$
• Possibility of ferro-octupolar order in Ba${}_2$CaOsO${}_6$ assessed by X-ray magnetic dichroism measurements
• Coupled-cluster approach to vibronic effects in resonant inelastic x-ray scattering of quantum materials: Application to a $5d^1$ rhenium oxide
• Intersite Coulomb repulsion driven quadrupole instability and magnetic ordering in the orbital frustrated Ba${}_2$MgReO${}_6$
• Polaron-driven switching of octupolar order in doped 5d${}^2$ double perovskite