Correlated vs. conventional insulating behavior in the Jeff=1/2 vs. 3/2 bands in the layered iridate Ba2IrO4

TL;DR

This study investigates the temperature-dependent electronic structure of Ba2IrO4 thin films, revealing distinct behaviors of Jeff=1/2 and 3/2 bands across the Neel transition using advanced spectroscopy.

Contribution

It provides new insights into the contrasting temperature responses of relativistic bands in layered iridates, highlighting the complex interplay of electronic states near magnetic transitions.

Findings

Jeff=1/2 band gap softens approaching TN

Jeff=3/2 band remains largely unchanged with temperature

Charge gap persists into the paramagnetic state

Abstract

We employ molecular beam epitaxy to stabilize Ba2IrO4 thin films and utilize in situ angle-resolved photoemission spectroscopy to investigate the evolution of its electronic structure through the Neel temperature TN. Our measurements indicate that dispersions of the relativistic Jeff=1/2 and 3/2 bands exhibit an unusual dichotomy in their behavior through the Neel transition. Although the charge gap survives into the paramagnetic state, only the Jeff=1/2 state exhibits a strong temperature dependence and its gap softens with increasing temperature approaching TN, while the nearly fully occupied Jeff=3/2 state which remains nearby in energy exhibits negligible changes with temperature.