Intermediately coupled type-II superconductivity in a La-based kagome metal La₃Al

We present a comprehensive investigation into the superconducting properties of La₃Al, a La-based metal with a kagome structure. La₃Al crystallizes in a Ni₃Sn-type crystal structure (space group P6₃/mmc), where the La atoms form a kagome lattice. Resistivity measurements reveal superconducting transition with $T_{\mathrm{c}}^{\mathrm{onset}}=6.37$ K and $T_{\mathrm{c}}^{\mathrm{zero}}=6.18$ K. In magnetic susceptibility measurements, the superconducting transition is observed at 6.16 K. The lower and upper critical fields are determined to be 22.17 mT and 6.69 T, respectively. Heat capacity measurements confirm the bulk superconductivity, showing a normalized specific heat change of ΔC_e / (γT_c) = 2.16 and an electron–phonon coupling strength of λ_ep = 0.92. DFT calculations reveal the intricate band structure of La₃Al. The notable specific heat jump, coupled with the electron–phonon coupling strength λ_ep, indicates that La₃Al exhibits characteristics of an intermediately coupled type-II superconductor.