# Octahedral tilting induced isospin reorientation transition in iridate heterostructures

## TL;DR

This paper investigates how octahedral tilting in iridate heterostructures induces an isospin reorientation transition, revealing the sensitivity of magnetic order to structural distortions through a combined spin model and Hubbard model analysis.

## Contribution

It introduces a realistic Hubbard model incorporating octahedral tilting effects, demonstrating the tilting-induced isospin reorientation transition in layered iridate superlattices.

## Key findings

- Reduced magnon energy gap with tilting
- Reorientation from c-axis to ab-plane AFM order
- Confirmation of spin model predictions by Hubbard model

## Abstract

Iridate heterostructures are gaining interest as their magnetic properties are much more sensitive to structural distortion compared to pure spin systems due to spin-orbital entanglement induced by strong spin-orbit coupling. While bulk monolayer and bilayer iridates show $ab$-plane canted and $c$-axis antiferromagnetic (AFM) order, recent experiments on layered iridate superlattices (SL) have revealed striking properties, especially in the bilayer SL. A spin model is presented including the tilting induced Kitaev type interactions, which illustrates the proclivity towards $ab$-plane canted AFM order. A realistic Hubbard model including spin-dependent hopping terms arising from octahedral rotation and tilting is constructed for the bilayer SL in isospin space, and magnetic excitations are investigated in the self-consistently determined magnetic state. The Hubbard model analysis confirms the spin model results and shows strongly reduced magnon energy gap and an isospin reorientation transition from $c$-axis to $ab$-plane canted AFM order with increasing tilting.