  High temperature superconductivity in cuprates arises from an electronic
state that remains poorly understood. We report the observation of a related
electronic state in a non-cuprate material Sr2IrO4 in which the unique cuprate
Fermiology is largely reproduced. Upon surface electron doping through in situ
deposition of alkali-metal atoms, angle-resolved photoemission spectra of
Sr2IrO4 display disconnected segments of zero-energy states, known as Fermi
arcs, and a gap as large as 80 meV. Its evolution toward a normal metal phase
with a closed Fermi surface as a function of doping and temperature parallels
that in the cuprates. Our result suggests that Sr2IrO4 is a useful model system
for comparison to the cuprates.
