Persistent Paramagnons Deep in the Metallic Phase of Sr_{2-x}La_{x}IrO_{4}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Magnetism

Background:

• Sr_{2-x}La_{x}IrO_{4} exhibits complex magnetic properties influenced by electron doping.
• Understanding magnetic excitations is crucial for characterizing emergent electronic phases in iridates.

Purpose of the Study:

• Investigate the impact of electron doping on magnetic excitations in Sr_{2-x}La_{x}IrO_{4}.
• Characterize the nature of magnetic order and excitations across the phase diagram.

Main Methods:

• Resonant inelastic x-ray scattering (RIXS) at the Ir L_{3} edge.
• Analysis of magnetic excitations, including magnons and spin-orbit excitons.

Main Results:

• Long-range magnetic order is lost with doping, replaced by short-range order (SRO).
• Dispersive, damped magnons persist in the SRO phase, described by a pseudospin-1/2 Heisenberg model.
• A doping-independent high-energy magnetic continuum and broadened spin-orbit excitons were observed.

Conclusions:

• Pseudospin-1/2 models provide a good starting point for describing low-energy magnetic dynamics in doped iridates.
• The study reveals the persistence and evolution of magnetic excitations in the metallic regime.