Mott gap collapse in lightly hole-doped Sr2−xKxIrO4

Abstract

The evolution of Sr₂IrO₄ upon carrier doping has been a subject of intense interest, due to its similarities to the parent cuprates, yet the intrinsic behaviour of Sr₂IrO₄ upon hole doping remains enigmatic. Here, we synthesize and investigate hole-doped Sr_2−xK_xIrO₄ utilizing a combination of reactive oxide molecular-beam epitaxy, substitutional diffusion and in-situ angle-resolved photoemission spectroscopy. Upon hole doping, we observe the formation of a coherent, two-band Fermi surface, consisting of both hole pockets centred at (π, 0) and electron pockets centred at (π/2, π/2). In particular, the strong similarities between the Fermi surface topology and quasiparticle band structure of hole- and electron-doped Sr₂IrO₄ are striking given the different internal structure of doped electrons versus holes.

Doped Sr₂IrO₄ is of interest because of its close similarities to La₂CuO₄, a parent compound of the cuprates. Nelson et al. reveal the intrinsic evolution of its electronic structure with hole doping by avoiding the strong in-plane disorder introduced by previously used chemical substitutions.