Fermi surface and pseudogap in highly doped Sr₂IrO₄

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• The electronic properties of electron-doped strontium iridescent oxide (Sr₂IrO₄) are not fully understood.
• The behavior of the Fermi surface and the pseudogap phase in this material remain elusive.

Purpose of the Study:

• To investigate the electronic structure of Sr_2-xLa_xIrO₄ at higher doping levels (x up to 0.2).
• To determine the fate of the Fermi surface and the pseudogap phase under increased electron doping.

Main Methods:

• High-resolution angle-resolved photoelectron spectroscopy (ARPES).
• Systematic doping of Sr₂IrO₄ with lanthanum (La).

Main Results:

• The antinodal pseudogap persists up to the highest doping level (x = 0.2).
• This pseudogap extends beyond the doping level (x* ≈ 0.16) where a sharp increase in Hall carrier density is observed.
• The pseudogap temperature boundary (T*) is approximately 200 K for x = 0.2.

Conclusions:

• Electron-doped iridates exhibit a unique phase where a large Hall density coexists with an anisotropic pseudogap.
• This phase breaks up the Fermi surface into disconnected arcs, challenging conventional understanding.
• The observed pseudogap behavior and temperature scale are comparable to those in cuprates.