Three-dimensional superconductivity induced by an extremely small amount of Li in LixSnSe2

Abstract

Unconventional superconductivity occurs often in materials with low dimensionality. Here, we report superconductivity observed in layered LixSnSe2 with the superconducting transition temperature Tc∼6 K. Through Li+ intercalation in semiconducting SnSe2 via electrochemical process, LixSnSe2 is formed with an extremely small x value as estimated from the c-axis lattice parameter, carrier concentration, and first-principles calculations. Electrical resistivity and magnetic susceptibility measurements allow the construction of both lower (Hc1ab) and upper critical field (Hc2abandHc2c) phase diagrams. While Hc2c obtained from 10% and 50% resistivity drops exhibits linear temperature dependence, Hc2c(90%resistivitydrop), Hc1ab, and Hc2ab can be described by the empirical formula Hci(T)=Hci(0)[1−(TTc0)2] (i=1, 2), giving Hc2c(0)=754 Oe, Hc1ab(0) = 27 Oe, and Hc2ab(0) = 1652 Oe. Using the Ginzburg-Landau formula, we further estimate that the c-axis penetration depth λc(0) = 396 nm and the coherence length anisotropy ξab(0) = 66.1 nm and ξc(0) = 30.3 nm. The fact that ξc(0) is much longer than the interlayer separation implies three-dimensional superconductivity with superconducting anisotropy ξab(0)/ξc(0) ∼ 2.2.

Source-reported materials — not catalogue approval

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