Observation of a d-wave gap in electron-doped Sr₂IrO₄

Journal Article · Mon Oct 12 04:00:00 EDT 2015 · Nature Physics

DOI:https://doi.org/10.1038/nphys3503· OSTI ID:1581047

Kim, Y. K.; Sung, N. H.; Denlinger, J. D.; Kim, B. J.

High-temperature superconductivity in cuprates emerges out of a highly enigmatic 'pseudogap' metal phase. The mechanism of high-temperature superconductivity is probably encrypted in the elusive relationship between the two phases, which spectroscopically is manifested as Fermi arcs—disconnected segments of zero-energy states—collapsing into d-wave point nodes upon entering the superconducting phase. Here, we reproduce this distinct cuprate phenomenology in the 5d transition-metal oxide Sr₂IrO₄. Using angle-resolved photoemission, we show that the clean, low-temperature phase of 6-8% electron-doped Sr₂IrO₄ has gapless excitations only at four isolated points in the Brillouin zone, with a predominant d-wave symmetry of the gap. Our work thus establishes a connection between the low-temperature d-wave instability and the previously reported high-temperature Fermi arcs in electron-doped Sr₂IrO₄ (ref.). Although the physical origin of the d-wave gap remains to be understood, Sr₂IrO₄ is the first non-cuprate material to spectroscopically reproduce the complete phenomenology of the cuprates, thus offering a new material platform to investigate the relationship between the pseudogap and the d-wave gap.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Scientific User Facilities Division (SC-22.3 )
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1581047
• Journal Information: Nature Physics, Journal Name: Nature Physics Journal Issue: 1 Vol. 12; ISSN 1745-2473
• Publisher: Nature Publishing Group (NPG)
• Country of Publication: United States
• Language: English