Superconducting properties of the Ti-doped KV3Sb5 kagome compound

Abstract

We present a comprehensive investigation of the synthesis, electrical transport, magnetic, and thermal properties of Ti-doped KV3Sb5. The parent compound, KV3Sb5, exhibits a charge-density-wave (CDW) transition at TCDW=78 K and superconductivity below a critical temperature (Tc) of 0.93 K. Upon light titanium doping, forming KTi0.15V2.85Sb5, the CDW transition is completely suppressed, while superconductivity is significantly enhanced, with Tc increasing to 3.6 K. Bulk superconductivity in the Ti-doped compound is confirmed by resistivity, magnetization, and heat capacity measurements. Anisotropic upper critical fields are observed, with Hc2 values of 2.12 T (in-plane) and 0.59 T (out-of-plane). To elucidate the origin of enhanced superconductivity, we analyze the electronic density of states (DOS) near the Fermi level. The Sommerfeld coefficient (γ), extracted from heat capacity data, indicates an increased DOS at the Fermi level, N(EF), in the Ti-doped sample, consistent with a BCS framework for superconductivity. Density functional theory calculations further support this enhancement of N(EF) and reveal modifications to the Fermi surface topology with Ti doping, suggesting weakened Fermi surface nesting that may be responsible for the suppression of the CDW. These results provide a coherent picture in which chemical doping alters the delicate balance between competing CDW and superconducting phases, demonstrating a viable route to tune superconductivity in kagome lattice materials via chemical pressure.

Source-reported materials — not catalogue approval

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