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The transport properties of ultrathin 2H–NbSe2
Superconductor Science and Technology ( IF 3.7 ) Pub Date : 2021-01-15 , DOI: 10.1088/1361-6668/abd14f
L B Lei 1, 2, 3 , C Zhang 2, 3, 4 , A B Yu 2, 3, 4 , Y F Wu 5 , W Peng 2, 3, 4 , H Xiao 6 , S Qiao 1, 2, 3, 4 , T Hu 5
Affiliation  

The competing orders arising in a two-dimensional limit are the key to understanding unconventional superconductivity. The monolayer NbSe2 possessing a charge density wave (CDW) and superconducting orders provides a playground to study unconventional superconductivity. Here we fabricate an ultrathin 2H–NbSe2 device based on the mechanical exfoliation method and our electrode transfer technique. Detailed four-lead and two-lead transport measurements are performed in the ultrathin sample. The superconducting transition ( T c ) at 4.3 K and CDW transition at 70 K are found in the sample, consistent with the literature report for ultrathin 2H–NbSe2. The superconducting gap (Δ) of ultrathin 2H–NbSe2 is estimated by fitting the two-lead transport spectroscopy with the Blonder–Tinkham–Klapwijk (BTK) theory. We found that Δ( T ) exhibits a BCS-like temperature dependence with Δ $\approx$ 1.1 meV at 0 K and $\Delta/k_BT_c\approx\,\textbf{3}$. Meanwhile the gap-like features persist in the normal state and become unresolvable with the increasing temperature and magnetic field, suggesting a possible precursor superconductivity similar to the cuprate superconductors. Our results provide a new insight into superconductivity in ultrathin 2H–NbSe2.



中文翻译:

超薄2H–NbSe 2的传输性质

二维极限中产生的竞争订单是理解非常规超导性的关键。具有电荷密度波(CDW)和超导阶数的单层NbSe 2为研究非常规超导性提供了场所。在这里,我们基于机械剥落法和我们的电极转移技术制造了超薄2H–NbSe 2器件。在超薄样品中执行详细的四线和两线传输测量。在样品中发现了4.3 K处的超导转变(T c)和70 K处的CDW转变,这与超薄2H–NbSe 2的文献报道一致。超薄2H–NbSe 2的超导间隙(Δ) 通过用Blonder–Tinkham–Klapwijk(BTK)理论拟合两线传输光谱来估算。我们发现Δ(T)在0 K和时表现出BCS样的温度依赖性,其Δ1.1 meV 。同时,间隙状特征在正常状态下保持不变,并且随着温度和磁场的增加而变得不可分辨,这表明可能存在类似于铜酸盐超导体的前体超导性。我们的结果为超薄2H–NbSe 2中的超导性提供了新的见解。 $ \约$$ \ Delta / k_BT_c \ approx \,\ textbf {3} $

更新日期:2021-01-15
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