Abstract
Good-quality hexagonal NbSe2 single crystals were prepared. In 2H-NbSe2, superconducting and charge density wave (CDW) transitions were found at T s = 7.4 K and T c = 35 K respectively as reported previously. We have noticed that these two transitions are changed to T c = 42 K and T s = 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/T s, from resistivity and explained in terms of coherence length. From the relation, \(H_{\rm c2} (T)=H_{\rm c2} (0)[1-t^2]\), \(H_{\rm c2}^l (0)\) was calculated as ~8.15 T and 16.98 T at t = 0.84 in 2H-NbSe2 and 4H-NbSe2 respectively. However, \(H_{\rm c2}^t (0) = 2.68\)T for both single crystals.
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NAIK, I., RASTOGI, A.K. Charge density wave and superconductivity in 2H- and 4H-NbSe2: A revisit. Pramana - J Phys 76, 957–963 (2011). https://doi.org/10.1007/s12043-011-0028-0
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DOI: https://doi.org/10.1007/s12043-011-0028-0