Multipole Superconductivity in Nonsymmorphic Sr2IrO4

Abstract

Discoveries of marked similarities to high-Tc cuprate superconductors point to the realization of superconductivity in the doped Jeff=1/2 Mott insulator Sr2IrO4. Contrary to the mother compound of cuprate superconductors, several stacking patterns of in-plane canted antiferromagnetic moments have been reported, which are distinguished by the ferromagnetic components as −++−, ++++, and −+−+. In this paper, we clarify unconventional features of the superconductivity coexisting with −++− and −+−+ structures. Combining the group theoretical analysis and numerical calculations for an effective Jeff=1/2 model, we show unusual superconducting gap structures in the −++− state protected by nonsymmorphic magnetic space group symmetry. Furthermore, our calculation shows that the Fulde-Ferrell-Larkin-Ovchinnikov superconductivity is inevitably stabilized in the −+−+ state since the odd-parity magnetic −+−+ order makes the band structure asymmetric by cooperating with spin-orbit coupling. These unusual superconducting properties are signatures of magnetic multipole order in nonsymmorphic crystal.

Source-reported materials — not catalogue approval

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