# Magnetic excitations in hole-doped Sr2IrO4: A comparison with electron-doped cuprates

## TL;DR

This study investigates how magnetic and orbital excitations evolve with hole doping in Sr2IrO4, revealing that spin dynamics resemble electron-doped cuprates and highlighting the role of magnetic order in exciton propagation.

## Contribution

It provides detailed RIXS measurements of magnetic and orbital excitations across doping levels in Sr2IrO4, showing the hardening of magnons and the disappearance of spin fluctuations in the paramagnetic phase.

## Key findings

- Magnon modes harden with increased hole doping.
- Spin fluctuations vanish in the paramagnetic phase.
- Orbital excitations become dispersionless in the absence of magnetic order.

## Abstract

We have studied the evolution of magnetic and orbital excitations as a function of hole-doping in single crystal samples of Sr2Ir(1-x)Rh(x)O4 (0.07 < x < 0.42) using high resolution Ir L3-edge resonant inelastic x-ray scattering (RIXS). Within the antiferromagnetically ordered region of the phase diagram (x < 0.17) we observe highly dispersive magnon and spin-orbit exciton modes. Interestingly, both the magnon gap energy and the magnon bandwidth appear to increase as a function of doping, resulting in a hardening of the magnon mode with increasing hole doping. As a result, the observed spin dynamics of hole-doped iridates more closely resemble those of the electron-doped, rather than hole-doped, cuprates. Within the paramagnetic region of the phase diagram (0.17 < x < 0.42) the low-lying magnon mode disappears, and we find no evidence of spin fluctuations in this regime. In addition, we observe that the orbital excitations become essentially dispersionless in the paramagnetic phase, indicating that magnetic order plays a crucial role in the propagation of the spin-orbit exciton.