Possible high-Tc superconductivity exceeding 100 K in Ir-substituted perovskite-type manganese oxides

Abstract The search for new high-Tc superconductors has commonly focused on layered perovskite compounds with isoelectronic or isostructural properties similar to those of cuprates.1, 2 For example, in 2019, a family of 3d nickel-based superconductors (Nd, Sr)NiO2 was discovered by Hwang et al.3More recently, Ca2RuO4, a 4d transition metal oxide, received attention as a superconductor with Tc = 64 K in coexistence with ferromagnetism in nanofilm single crystals.4 Even the 5d transition metal oxide Sr2IrO4 was thoroughly studied as a possible high-Tc superconductor.5 While no zero-resistance state has yet been observed, surface-electron-doped Sr2IrO4 has shown a spectroscopic signature consistent with a superconducting gap.6 However, despite such intensive exploration of analogous structures, no materials other than cuprates or single-layer FeSe/SrTiO3 [Ref. 7] have been reported to exhibit high-Tc superconductivity above 100 K under ambient pressure. In this study, we report observations of possible new high-Tc superconductivity in a non-layered perovskite, Ir-substituted (La, Sr)MnO3 (LSMIO) thin films. LSMIO samples with Ir compositions of approximately 10% were confirmed to exhibit the zero-resistance state with onset temperatures exceeding 100 K. Furthermore, their magnetic field response was observed to be characteristic of conventional superconductors. All these results strongly indicated that LSMIO showed the most promise as a new high-Tc superconductor among perovskite oxides. The present discovery will boost interest in new theoretical frameworks for unconventional but possible superconductivity in LSMIO, opening a frontier for research on high-Tc superconductors.