Charge density wave and superconductivity in 2H- and 4H-NbSe2: A revisit

Pramana

A K Rastogi¹  I Naik1² 

[1] School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067, India$$;Department of Physics, North Orissa University, Baripada 757 003, India$$

关键词: Transition metal compounds;    superconductivity.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

Good-quality hexagonal NbSe2 single crystals were prepared. In 2H-NbSe2, superconducting and charge density wave (CDW) transitions were found at 𝑇𝑠 = 7.4 K and 𝑇𝑐 = 35 K respectively as reported previously. We have noticed that these two transitions are changed to 𝑇𝑐 = 42 K and 𝑇𝑠 = 6.5 K, in 4H-NbSe2. Thermopower has shown clear anomaly at CDW transitions. The anisotropic upper critical field was calculated as ∼ 3 and 6.3 for 2H- and 4H-single crystals around 𝑡 = 0.81, where 𝑡 = 𝑇/𝑇𝑠, from resistivity and explained in terms of coherence length. From the relation, $H_{c2}(𝑇) = H_{c2}(0)[1 − 𝑡^2]$, $H^l_{c2}(0)$ was calculated as ∼ 8.15 T and 16.98 T at 𝑡 = 0.84 in 2H-NbSe2 and 4H-NbSe2 respectively. However, $H^𝑡_{c2}(0) = 2.68$ T for both single crystals.

【 授权许可】

Unknown