Magnetization density distribution of Sr${}_2$IrO${}_4$: Deviation from a local $j_{\text{eff}}=1/2$ picture

Abstract

$5d$ iridium oxides are of huge interest due to the potential for new quantum states driven by strong spin-orbit coupling. The strontium iridate Sr${}_2$IrO${}_4$ is particularly in the spotlight because of the so-called $j_{\text{eff}}=1/2$ state consisting of a quantum superposition of the three local $t_{2g}$ orbitals with -- in its most simple version -- nearly equal population, which stabilizes an unconventional Mott insulating state. Here, we report an anisotropic and aspherical magnetization density distribution measured by polarized neutron diffraction in a magnetic field up to 5~T at 4~K, which strongly deviates from a local \jeffHalf picture even when distortion-induced deviations from the equal weights of the orbital populations are taken into account. Once reconstructed by the maximum entropy method and multipole expansion model refinement, the magnetization density shows cross-shaped positive four lobes along the crystallographic tetragonal axes with a large spatial extent, showing that the $xy$ orbital contribution is dominant. The analogy to the superconducting copper oxide systems might then be weaker than commonly thought.

arXiv comment3 figures + supplementary file included

References in corpus (21)

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• Long-range interactions in the effective low energy Hamiltonian of Sr2IrO4: a core level resonant inelastic x-ray scattering study
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• Magnetic critical properties and basal-plane anisotropy of Sr${}_2$IrO${}_4$

Cited by in corpus (10)

• Magnetic order and 5d1 multipoles in a rhenate double perovskite Ba2MgReO6
• Oxygen magnetic polarization, nodes in spin density, and zigzag spin order in oxides
• Direct observation of oxygen polarization in Sr${}_2$IrO${}_4$ by O $K$-edge x-ray magnetic circular dichroism
• Diffraction by multipoles in a 5d2 rhenium double perovskite
• Modeling multiorbital effects in Sr2IrO4 under strain and a Zeeman field
• Constraints on the two-dimensional pseudo-spin 1/2 Mott insulator description of Sr${}_2$IrO${}_4$
• Evolution of the spectral lineshape at the magnetic transition in Sr2IrO4 and Sr3Ir2O7
• The rich phase diagram of the prototypical iridate Ba${}_2$IrO${}_4$: Effective low-energy models and metal-insulator transition
• Orbital-Selective Spin-Orbit Mott Insulator in Fractional Valence Iridate La${}_3$Ir${}_3$O${}_{11}$
• Intersite Coulomb repulsion driven quadrupole instability and magnetic ordering in the orbital frustrated Ba${}_2$MgReO${}_6$