Anomalous Nodal Gap in a Doped Spin-1/2 Antiferromagnetic Mott Insulator

Abstract

Many emergent phenomena appear in doped Mott insulators near the insulator-to-metal transition. In high-temperature cuprate superconductors, superconductivity arises when antiferromagnetic (AFM) order is gradually suppressed by carrier doping, and a $\text{d}$-wave superconducting gap forms when an enigmatic nodal gap evolves into a point node. Here, we examine electron-doped Sr${}_2$IrO${}_4$, the 5$\text{d}$-electron counterpart of cuprates, using angle-resolved photoemission spectroscopy. At low doping levels, we observe the formation of electronic states near the Fermi level, accompanied by a gap at the AFM zone boundary, mimicking the AFM gap in electron-doped cuprates. With increasing doping, a distinct gap emerges along the (0,0)-($\pi$,$\pi$) nodal direction, paralleling that observed in hole-doped cuprates. This anomalous nodal gap persists after the collapse of the AFM gap and gradually decreases with further doping. It eventually vanishes into a point node of the reported $\text{d}$-wave gap. These observations replicate the characteristic features in both electron- and hole-doped cuprates, indicating a unified route toward nodal metallicity in doped spin-1/2 AFM Mott insulators.

References in corpus (11)

• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Twisted Hubbard Model for Sr2IrO4: Magnetism and Possible High Temperature Superconductivity
• Fermi Arcs in a Doped Pseudospin-1/2 Heisenberg Antiferromagnet
• Phase competition in trisected superconducting dome
• Monte Carlo study of an unconventional superconducting phase in Ir-oxide J_{eff}=1/2 Mott insulators induced by carrier doping
• Evolution from a nodeless gap to d(x2-y2) form in underdoped La(2-x)SrxCuO4
• Intermediate Coupling Model of the Cuprates
• Unidirectional spin density wave state in metallic (Sr1-xLax)2IrO4
• Evolution of remnant Fermi surface state in lightly-doped correlated spin-orbit insulator Sr${}_{2-x}$La${}_x$IrO${}_4$
• Spectroscopic evidence for electron-boson coupling in electron-doped Sr${}_2$IrO${}_4$
• Nanoscale phase separation in deep underdoped Bi${}_2$Sr${}_2$CuO${}_{6+\delta }$ and Ca${}_2$CuO${}_2$Cl${}_2$