Superconducting Transition Temperature of 2H−TaS<sub>2</sub> Intercalation Compounds Determined by the Phonon Spectrum

Schlicht, Anja; Schwenker, M.; Biberacher, and W.; Lerf, A.

doi:10.1021/jp010089a

Cited by 23 publications

(28 citation statements)

References 21 publications

(23 reference statements)

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“…A traditional way for fabricating intercalated layered dichalcogend compounds consists of two steps, the first step is to prepare poly-crystalline compound or single crystal of M X 2 by chemical reaction or iodine-transport reaction 7,20 ; Secondly, the intercalation is carried out by chemical treatments, the samples are dipped into concentrated solutions containing the intercalated atoms 7,16,20 , or exposed to metal vapors in a closed ampoule 16 . A new method suited for preparing samples for the studies of surface science was also reported, the intercalated compounds were prepared by in situ evaporation of metal atoms to the (0 0 0 1) cleaved surface of the TMDC's crystals.…”

Section: Methodsmentioning

confidence: 99%

Fabrication and superconductivity ofNaxTaS2crystals

et al. 2005

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In this paper we report the growth and superconductivity of N axT aS2 crystals. The structural data deduced from X-ray diffraction pattern shows that the sample has the same structure as 2H − T aS2. A series of crystals with different superconducting transition temperatures (Tc) ranging from 2.5 K to 4.4 K were obtained. It is found that the Tc rises with the increase of N a 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 − T aS2 (Tc = 0.8 K, TCDW ≈ 70 K), no signal of charge density wave (CDW) was observed in samples N a0.1T aS2 and N a0.05T aS2. However, in some samples with lower Tc, the CDW appears again at about 65 K. Comparison between the anisotropic resistivity indicates that the anisotropy becomes smaller in samples with more N a 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 N axT aS2 is caused mainly by the suppression to the CDW in 2H − T aS2, 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 − T aS2.

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Section: Methodsmentioning

confidence: 99%

Fabrication and superconductivity ofNaxTaS2crystals

et al. 2005

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“…[19] The nanowires exhibit superconductivity, with an onset temperature of 3.4 K (Figure 4). This behavior is in stark contrast with that of bulk 2H-TaS 2 , which exhibits superconductivity below 1 K (T c = 0.6 [14] or 0.8 K [20] ). Further, the transition temperature of the 2H-TaS 2 nanowires is higher than that reported for the 6R-TaS 2 nanobelts (T c = 2.7 K).…”

mentioning

confidence: 88%

Single‐Step Synthesis and Surface‐Assisted Growth of Superconducting TaS₂ Nanowires

Dunnill¹,

Edwards²,

Brown³

et al. 2006

Angew Chem Int Ed

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“…Another class of TMD intercalation compounds is the hydrates with transition metal ions as intercalants into 2H-TaS 2 [138][139][140][141][142][143][144][145]. These compounds have the general composition M x (H 2 O) y T χ 2 , where T can be either Ta or Nb, χ = S, and M can be an alkali or a rare earth ion.…”

Section: Intercalated Transition Metal Dichalcogenidesmentioning

confidence: 99%

Pristine and intercalated transition metal dichalcogenide superconductors

Klemm

2015

Physica C: Superconductivity and its Applications

116

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Transition metal dichalcogenides (TMDs) are quasi-two-dimensional layered compounds that exhibit strongly competing effects of charge-density wave (CDW) formation and superconductivity (SC). The weak van der Waals interlayer bonding between hexagonal layers of octahedral or trigonal prismatic TMD building blocks allows many polytypes to form. In the single layer 1T polytype materials, one or more CDW states can form, but the pristine TMDs are not superconducting. The 2H polytypes have two or more Fermi surfaces and saddle bands, allowing for dual orderings, which can be coexisting CDW and SC orderings, two SC gaps as in MgB2, two CDW gaps, and possibly even pseudogaps above the onset TCDWs of CDW orderings. Higher order polytypes allow for multiple CDW gaps and at least one superconducting gap. The CDW transitions TCDWs usually greatly exceed the superconducting transitions at their low Tc values, their orbital order parameters (OPs) are generally highly anisotropic and can even contain nodes, and the SC OPs can be greatly affected by their simultaneous presence. The properties of the CDWs ubiquitously seen in TMDs are remarkably similar to those of the pseudogaps seen in the high-Tc cuprates. In 2H-NbSe2, for example, the CDW renders its general s-wave SC OP orbital symmetry to be highly anisotropic and strongly reduces its Josephson coupling strength (IcRn) with the conventional SC, Pb. Hence, the pristine TMDs are highly "unconventional" in comparison with Pb, but are much more "conventional" than are the ferromagnetic superconductors such as URhGe. Applied pressure and intercalation generally suppress the TMD CDWs, allowing for enhanced SC formation, even in the 1T polytype materials. The misfit intercalation compound (LaSe)1.14(NbSe2) and many 2H-TMDs intercalated with organic Lewis base molecules, such as TaS2(pyridine) 1/2 , have completely incoherent c-axis transport, dimensional-crossover effects, and behave as stacks of intrinsic Josephson junctions. Except for the anomalously large apparent violation of the Pauli limit of the upper critical field of (LaSe)1.14(NbSe2), these normal state and superconducting properties of these intercalation compounds are very similar to those seen in the high-Tc superconductor, Bi2Sr2CaCu2O 8+δ and in the organic layered superconductor, κ-(ET)2Cu[N(CN)2]Br, where ET is bis(ethylenedithio)tetrathiafulvalene. Electrolytic intercalation of TMDs with water and metallic ions leads to compounds with very similar properties to cobaltates such as NaxCoO2 · yH2O.

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Superconducting Transition Temperature of 2H−TaS₂ Intercalation Compounds Determined by the Phonon Spectrum

Cited by 23 publications

References 21 publications

Fabrication and superconductivity ofNaxTaS2crystals

Fabrication and superconductivity ofNaxTaS2crystals

Single‐Step Synthesis and Surface‐Assisted Growth of Superconducting TaS₂ Nanowires

Pristine and intercalated transition metal dichalcogenide superconductors

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Superconducting Transition Temperature of 2H−TaS2 Intercalation Compounds Determined by the Phonon Spectrum

Cited by 23 publications

References 21 publications

Fabrication and superconductivity ofNaxTaS2crystals

Fabrication and superconductivity ofNaxTaS2crystals

Single‐Step Synthesis and Surface‐Assisted Growth of Superconducting TaS2 Nanowires

Pristine and intercalated transition metal dichalcogenide superconductors

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Superconducting Transition Temperature of 2H−TaS₂ Intercalation Compounds Determined by the Phonon Spectrum

Single‐Step Synthesis and Surface‐Assisted Growth of Superconducting TaS₂ Nanowires