Converting KTeO3 into high-temperature topological superconductors via carrier-doped suppression of Te multivalency

Abstract

Most of the superconductors with nontrivial band topology discovered so far are constrained to materials with low superconducting transition temperatures (Tc) and narrow topological energy gaps. Here we use first-principles calculations to demonstrate that KTeO3 can be converted into high-Tc superconductors with concomitant large topological energy gaps via effective suppression of the multivalency of Te. We first show that the inherent multivalent nature of Te in pristine KTeO3, accompanied by too strong electron-phonon coupling, leads to a dominant charge density wave (CDW) instability. Next, we find that when the Te multivalency is suppressed by proper gating or partially substituting K with Ba at moderate pressure, the electron-phonon coupling is significantly weakened, and the CDW instability yields to a dominant superconducting order with a maximum Tc of ∼60 K right at the CDW-to-superconductivity transition. Furthermore, the superconducting systems exhibit nontrivial band topology with unusually wide energy gaps of ∼0.8 eV, thereby serving as appealing platforms for realizing topological superconductivity with exceptional robustness and tunability.

Source-reported materials — not catalogue approval

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