Topological ultranodal pair states in iron-based superconductors

Journal Article · Mon Jan 27 00:00:00 EST 2020 · Nature Communications

DOI:https://doi.org/10.1038/s41467-020-14357-2· OSTI ID:1619771

Setty, Chandan; Bhattacharyya, Shinibali ; Cao, Yifu ; Kreisel, Andreas ; Hirschfeld, P. J.

Abstract Bogoliubov Fermi surfaces are contours of zero-energy excitations that are protected in the superconducting state. Here we show that multiband superconductors with dominant spin singlet, intraband pairing of spin-1/2 electrons can undergo a transition to a state with Bogoliubov Fermi surfaces if spin-orbit coupling, interband pairing and time reversal symmetry breaking are also present. These latter effects may be small, but drive the transition to the topological state for appropriate nodal structure of the intra-band pair. Such a state should display nonzero zero-bias density of states and corresponding residual Sommerfeld coefficient as for a disordered nodal superconductor, but occurring even in the pure case. We present a model appropriate for iron-based superconductors where the topological transition associated with creation of a Bogoliubov Fermi surface can be studied. The model gives results that strongly resemble experiments on FeSe _{1− x} S _x across the nematic transition, where this ultranodal behavior may already have been observed.

• Research Organization: Univ. of Florida, Gainesville, FL (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
• Grant/Contract Number: FG02-05ER46236
• OSTI ID: 1619771
• Alternate ID(s): OSTI ID: 1603797
• Journal Information: Nature Communications, Journal Name: Nature Communications Vol. 11 Journal Issue: 1; ISSN 2041-1723
• Publisher: Nature Publishing Group
• Country of Publication: United Kingdom
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY