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  • Letter
  • Open Access

When spin-orbit coupling meets local lattice distortions in Mott-like insulator iridates: The case of Sr2IrO4

A. Zafar1, M. Jakhar2, AM Milinda Abeykoon3, and V. Petkov1,*

  • *Contact author: petko1vg@cmich.edu
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Phys. Rev. Research 8, L032024 – Published 12 August, 2026

DOI: https://doi.org/10.1103/g3cv-g5zj

Abstract

Focusing on Sr2IrO4 as a model system, we investigate the poorly understood role of local lattice distortions in governing the unusual electronic properties of Mott-like insulating iridates. Using total x-ray scattering combined with structural modeling, we find no evidence for the previously proposed lowering of the average crystal symmetry. Instead, we uncover previously overlooked local lattice distortions that create two distinct IrO6-octahedral layers already in the room-temperature paramagnetic insulating phase, thereby breaking the crystal symmetry locally rather than globally. Density functional theory calculations based on the experimentally determined structures show that the progressive strengthening of the local distortions with decreasing temperature may account for the enhanced band gap observed in the weakly ferromagnetic insulating phase. Our findings highlight the importance of local lattice distortions in shaping the electronic ground state of Sr2IrO4 and point to a broader role for hidden distortions and local symmetry breaking across Ir-based spin-orbit-coupled materials.

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Phys. Rev. Research 8, L032024– Published 12 August, 2026
  • Received 1 April 2026
  • Revised 8 June 2026
  • Accepted 24 July 2026
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