The large size single crystals of (SnSe)$_{ 1.16}$(NbSe$_2$) misfit layered compound were grown and superconductivity with $T_c$ of 3.4 K was first discovered in this system. Powder X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) clearly display the misfit feature between SnSe and NbSe$_2$ subsystems. The Sommerfeld coefficient $\gamma$ inferred from specific-heat measurements is 16.73 mJ mol$^{ -1}$ K$^{ -2}$, slightly larger than the usual misfit compounds. The normalized specific heat jump $\Delta$$C_e$/$\gamma$$T_{ \rm c}$ is about 0.98, and the electron-phonon coupling constant $\lambda$$_{ e-ph}$ is estimated to be 0.80. The estimated value of the in-plane upper critical magnetic field, $H_{ c2}^{ ab}$(0), is about 7.82 T, exceeding the Pauli paramagnetic limit slightly. Both the specific-heat and $H_{ c2}$ data suggest that (SnSe)$_{ 1.16}$(NbSe$_2$) is a multi-band superconductor.
Categories: cond-mat.supr-con