We report on the temperature dependence of the in plane magnetic penetration depth (λab) and first penetration field (Hf∝1/λab2(T) for H∥c) in 2H-NbS2 single crystals. An exponential temperature dependence is clearly observed in λab(T) at low temperature, signing the presence of a fully open superconducting gap. This compound is the only superconducting 2H-dichalcogenide which does not develop a charge density wave (CDW). However as previously observed in 2H-NbSe2, this gap (Δ1=1.1kBTc) is significantly smaller than the standard BCS weak coupling value. At higher temperature, a larger gap (Δ2=1.8kBTc) has to be introduced to describe the data which are compatible with a two gap model. The superconducting gaps are hence very similar in NbS2 and NbSe2 and we show here that both of them open in the strongly coupled Nb tubular sheets independently of the presence of a CDW or not.
@article{arxiv.1301.1845,
title = {In-plane magnetic penetration depth in NbS$_{2}$},
author = {Pascale Diener and Maxime Leroux and Laurent Cario and Thierry Klein and Pierre Rodiere},
journal= {arXiv preprint arXiv:1301.1845},
year = {2015}
}