Two-band superconductivity in intercalated rhombohedral ZrNCl

The multiband superconductor offers a unique venue for investigating the interplay between Cooper pairing and inter-band interactions. Here we report the emergence of two-band superconductivity in hybridized superlattice Na${}_{\mathrm{0.1}}$(1,3-diaminopropane)${}_{\mathrm{0.25}}$ ZrNCl. The intercalation of organic molecules and Na ions into the interlayer modulates the electronic structure near the Fermi surface, and promotes the emergence of intrinsic superconductivity with onset transition temperature $T_c=15$ K. Systematical investigations of upper critical field $H_{\mathrm{c2}}$ reveals that temperature dependence of $H_{\mathrm{c2}}$ can be well-described by two-band theory, yielding the out-of-plane and in-plane $H_{\mathrm{c2}}$ values of 2.9 T and 11.5 T, respectively. Furthermore, analysis of the reversible magnetization data confirms the intrinsic two-band characteristics, which deviate significantly from the predictions of the single-band Ginzburg–Landau(GL)model. Meanwhile, the superconducting state exhibits a two-fold rotational symmetry under in-plane magnetic fields, contrasting with the three-fold symmetric ZrNCl lattice. Angle-dependent $H_{\mathrm{c2}}$ behavior aligns with the three-dimensional (3D) anisotropic GL model. These findings establish the intercalated rhombohedral ZrNCl as a compelling platform for exploring multiband superconductivity.