Mott gap collapse in lightly hole-doped Sr(2−x)K(x)IrO(4)

The evolution of Sr(2)IrO(4) upon carrier doping has been a subject of intense interest, due to its similarities to the parent cuprates, yet the intrinsic behaviour of Sr(2)IrO(4) upon hole doping remains enigmatic. Here, we synthesize and investigate hole-doped Sr(2−x)K(x)IrO(4) 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 Sr(2)IrO(4) are striking given the different internal structure of doped electrons versus holes.