Fabrication and superconductivity of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Na</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi mathvariant="normal">Ta</mml:mi><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>crystals

Fang, Lei; Wang, Yetang; Zou, Pengfei; Tang, Lunxian; Zhao, Xu; Chen, H.; Dong, C.; Shan, Lei; Wen, Hao

doi:10.1103/physrevb.72.014534

Cited by 128 publications

(91 citation statements)

References 24 publications

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“…Cu-intercalated 2H-TaS 2 shows enhancement of T c up to 4.7 K. 28 Copper behaves as n-type dopant and therefore its intercalation brings both disorder and charge transfer. 29 Similar doping and disorder interplay is expected with Na intercalation in 2H-TaS 2 , where T c was raised up to 4.4 K. 30 In contrast, isoelectronic substitution in 2H-TaSe 2−x S x single crystal alloy series allows for clear separation of disorder from doping-induced changes. The basic electronic structure of 2H-TaSe 2 , 2H-TaSeS, and 2H-TaS 2 is quite similar as shown in the Local Density Approximation (LDA) calculations (Supplementary Material), leaving disorder as the origin of the increase in T c .…”

Section: Discussionmentioning

confidence: 93%

Superconducting order from disorder in 2H-TaSe 2− x S x

Deng

Wang

et al. 2017

npj Quant Mater

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We report on the emergence of robust superconducting order in single crystal alloys of TaSe 2−x S x (0 ≤ × ≤ 2). The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe 2 and TaS 2 . The evolution of superconducting critical temperature T c (x) correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high-temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe 2 and/or 2H-TaS 2 . It is known that in these materials superconductivity is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order.npj Quantum Materials (2017) 2:11 ; doi:10.1038/s41535-017-0016-9 INTRODUCTIONThe interplay of disorder and interactions is a fruitful area of investigation. In the absence of electron-electron interactions, disorder can turn a metallic system into an Anderson insulator, 1 but can remain metallic when interactions are important. The additional complexity of competing orders such superconductivity with charge density wave (CDW) or magnetism makes this problem one of the most challenging frontiers in physics. 2-5 A large body of literature is devoted to this interplay in nearly magnetic materials. 6 The interplay of disorder and superconductivity in CDW materials have been less explored than its magnetic analog.Superconductivity and CDW are traditionally viewed as weakcoupling Fermi surface instabilities due to electron-phonon coupling. 7 Arguments have been made both for their cooperation and competition. 8,9 Hexagonal transition metal dichalcogenide 2H-TaSe 2 (P63/mmc space group) undergoes a second-order transition to an incommensurate CDW at 122 K followed by a first-order lock-in transition to a commensurate CDW (CCDW) phase at 90 K, eventually becoming superconducting below 0.14 K upon cooling. 10, 11 2H-TaS 2 has T c = 0.8 K below an in-plane CCDW at 78 K. 10,12 The CDW mechanism in 2H-TaSe 2 involves an electron instability in the bands nested away from the Fermi surface, whereas 2H-TaS 2 features a polar charge and orbital order. 13,14 CDW in 2H-TaSe 2 is dominated by hopping between next-nearest neighbors that creates three weakly coupled triangular sublattices. 15 It is of interest to note that the 2H-TaSe 2 is quasi-twodimensional (2D) metal with pseudogap and with c-axis resistivity 25-50 times higher than the in-plane resistivity, i.e., ρ c (T) >> ρ ab (T). 10,13,[16][17][18] Here, we report that in the 2H-TaSe 2−x S x alloy series the CDW is suppressed and the superconductivity is maximized with

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Section: Discussionmentioning

confidence: 93%

Superconducting order from disorder in 2H-TaSe 2− x S x

Deng

Wang

et al. 2017

npj Quant Mater

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“…In this way, for instance, superconductivity can be enhanced or suppressed, sometimes in competition with CDW phases. 4,5 Among the TMDC, 1T-TiSe 2 turns out to be an interesting and enigmatic material. At the critical temperature of T c Ӎ 200 K, the system undergoes a second-order phase transition, characterized notably by a peaking resistivity 6,7 ͓see Fig.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent photoemission on1T-TiSe2: Interpretation within the exciton condensate phase model

et al. 2010

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The charge-density-wave phase transition of 1T-TiSe 2 is studied by angle-resolved photoemission over a wide temperature range. An important chemical-potential shift which strongly evolves with temperature is evidenced. In the framework of the exciton condensate phase, the detailed temperature dependence of the associated order parameter is extracted. Having a mean-field-like behavior at low temperature, it exhibits a nonzero value above the transition, interpreted as the signature of strong excitonic fluctuations, reminiscent of the pseudogap phase of high-temperature superconductors. Integrated intensity around the Fermi level is found to display a trend similar to the measured resistivity and is discussed within the model.

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“…Intercalation of Na into 2H-TaS 2 to form Na x TaS 2 (0 < x < 0.10), for example, shows an increase in T c to 4.4 K (20). Further, the resistive and spectroscopic signatures of the CDW weaken on Na doping (20,21). Fe x TaS 2 was found to have a T c of approximately 3.5 K when x = 0.05, with T c fully suppressed for x > 0.…”

Section: Introductionmentioning

confidence: 99%

Tuning the charge density wave and superconductivity inCuxTaS2

et al. 2008

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We report the characterization of layered, 2H-type Cu x TaS 2 , for 0 ≤ x ≤ 0.12. The charge density wave (CDW), at 70 K for TaS 2 , is destabilized with Cu doping. The sub-1K superconducting transition in undoped 2H-TaS 2 jumps quickly to 2.5 K at low x, increases to 4.5 K at the optimal composition Cu 0.04 TaS 2 , and then decreases at higher x. The electronic contribution to the specific heat, first increasing and then decreasing as a function of Cu content, is 12 mJ mol -1 K -2 at Cu 0.04 TaS 2 . Electron diffraction studies show that the CDW remains present at the optimal superconducting composition, but with both a changed q vector and decreased coherence length. We present an electronic phase diagram for the system.

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Fabrication and superconductivity ofNaxTaS2crystals

Cited by 128 publications

References 24 publications

Superconducting order from disorder in 2H-TaSe 2− x S x

Superconducting order from disorder in 2H-TaSe 2− x S x

Temperature-dependent photoemission on1T-TiSe2: Interpretation within the exciton condensate phase model

Tuning the charge density wave and superconductivity inCuxTaS2

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