Anisotropy dependence of the fluctuation spectroscopy in the critical and gaussian regimes in superconducting NaFe1−xCo x As single crystals

• Published in: Scientific reports Vol. 8; no. 1; p. 8556
• Main Authors: Ahmad, D., Choi, W. J., Sóñora, D., Oh, Yoon Seok, Mosqueira, J., Park, Tuson, Kwon, Yong Seung
• Format: Journal Article
• Language: English
• Published: 04.06.2018
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-26939-8

Abstract We investigate thermal fluctuations in terms of diamagnetism and magnetotransport in superconducting NaFe 1− x Co x As single crystals with different doping levels. Results show that in the case of optimal doped and lightly overdoped ( x  = 0.03, 0.05) crystals the analysis in the critical as well as in the Gaussian fluctuation regions is consistent with the Ginzburg-Landau 3D fluctuation theory. However, in the case of strongly overdoped samples ( x ≥ 0.07) the Ullah-Dorsey scaling of the fluctuation induced magnetoconductivity in the critical region confirms that thermal fluctuations exhibit a 3D anisotropic nature only in a narrow temperature region around T c ( H ). This is consistent with the fact that in these samples the fluctuation effects in the Gaussian region above T c may be described by the Lawrence-Doniach approach. Our results indicate that the anisotropy of these materials increases significantly with the doping level.