2005/02/28 by Leiming Fang, L. Fang, Yetang Wang +14
Chemistry · Materials Science · Physics and Astronomy · #Electronic and Structural Properties of Oxides #Inorganic Fluorides and Related Compounds #Physics of Superconductivity and Magnetism #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.72.014534
published as Phys. Rev. B72, 014534(2005) · 8 pages, 13 figures, To appear in Physical Review B
arxiv created 2005/05/25 · openalex publication_date 2005/07/22 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In this paper we report the growth and superconductivity of NaxTaS2 crystals. The structural data deduced from x-ray diffraction pattern shows that the sample has the same structure as 2H\ensuremath-TaS2. A series of crystals with different superconducting transition temperatures (Tc) ranging from 2.5\phantom\rule0.3em0exK\phantom\rule0.3em0exto\phantom\rule0.3em0ex4.4\phantom\rule0.3em0exK were obtained. It is found that the Tc rises with the increase of Na content determined by energy-dispersive x-ray microanalysis(EDX) of scanning electron microscope (SEM) on these crystals. Compared with the resistivity curve of un-intercalated sample 2H\ensuremath-TaS2 (Tc=0.8\phantom\rule0.3em0exK, TCDW\ensuremath≈70\phantom\rule0.3em0exK), no signal of charge density wave (CDW) was observed in samples Na0.1TaS2 and Na0.05TaS2. However, in some samples with lower Tc, the CDW appears again at about 65\phantom\rule0.3em0exK. Comparison between the anisotropic resistivity indicates that the anisotropy becomes smaller in samples with more Na intercalation (albeit a weak semiconducting behavior along c-axis) and thus higher Tc. It is thus concluded that there is a competition between the superconductivity and the CDW. With the increase of sodium content, the rise of Tc in NaxTaS2 is caused mainly by the suppression to the CDW in 2H\ensuremath-TaS2, and the conventional rigid band model for layered dichalcogenide may be inadequate to explain the changes induced by the slight intercalation of sodium in 2H\ensuremath-TaS2.