Quasi-2D Fermi surface of superconducting line-nodal metal CaSb${}_2$

Abstract

We report on the Fermi surfaces and superconducting parameters of CaSb${}_2$ single crystals (superconducting below $T_{\text{c}}\sim 1.8\text{K}$) grown by the self-flux method. The frequency of de-Haas-van-Alphen and Shubnikov-de-Haas oscillations evidences a quasi-two-dimensional (quasi-2D) Fermi surface, consistent with one of the Fermi surfaces forming Dirac lines predicted by first-principles calculations. Measurements in the superconducting state reveal that CaSb${}_2$ is close to a type-I superconductor with the Ginzburg-Landau (GL) parameter of around unity. The temperature dependence of the upper critical field $H_{\text{c2}}$ is well described by a model considering two superconducting bands, and the enhancement of the effective mass estimated from $H_{\text{c2}}(0\text{K})$ is consistent with the quasi-2D band observed by the quantum oscillations. Our results indicate that a quasi-2D band forming Dirac lines contributes to the superconductivity in CaSb${}_2$.

13 pages, 13 figures

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• Nodal-line semimetals and their variance
• Subtle Structural Anomaly under Compression in Line-Nodal CaSb${}_2$