Strong enhancement of superconductivity at high pressures within the charge-density-wave states of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>2</mml:mn><mml:mi>H</mml:mi><mml:mtext>−</mml:mtext><mml:msub><mml:mi>TaS</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>2</mml:mn><mml:mi>H</mml:mi><mml:mtext>−</mml:mtext><mml:msub><mml:mi>TaSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mm

Freitas, D. C.; Rodière, Pierre; Osorio, Manuel; Navarro‐Moratalla, Efrén; Nemes, N. M.; Tissen, V. G.; Cario, Laurent; Coronado, Eugenio; Garcı́a-Hernández, M.; Vieǐra, S.; Núñez-Regueiro, M.; Suderow, Hermann

doi:10.1103/physrevb.93.184512

Cited by 108 publications

(62 citation statements)

References 58 publications

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“…23,37,38 Assuming similar bulk modulus to WSe 2 (72 GPa), 39 the estimated chemical pressure differences of 2H-TaSeS (T c = 3.7 K) when compared with 2H-TaSe 2 (T c = 0.14 K) and 2H-TaS 2 (T c = 0.8 K) are 6 GPa (positive pressure/contraction) and 2.8 GPa (negative pressure/expansion). Positive pressure increases considerably superconducting T c in both 2H-TaS 2 and 2H-TaS 2 ; 6 GPa brings T c in 2H-TaSe 2 up to about 3 K. 40 CDW is robust, surviving up to 20 GPa (2H-TaSe 2 ) and up to 16 GPa (2H-TaS 2 ). Clearly, chemical pressure may influence the rise of superconducting T c in S-doped 2H-TaSe 2 , but it cannot explain the absence of CDW in high-T c samples in the phase diagram (Fig.…”

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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“…Generally low superconducting critical temperatures prevents any Raman spectroscopy study of the SC state. In 2H-TaS 2 , an incommensurate CDW develops below 77 K followed by a superconducting state below T c =1 K. Recent reports [40] have shown a dramatic increase in T c with pressure, up to 8.5 K at 10 GPa. Then an observation of the coexisting superconducting and CDW states, and of the Higgs mode, becomes accessible using Raman scattering.…”

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confidence: 92%

“…This structure, sometimes observed in simple superconductors [51] and here observed up to 9.5 GPa in the pure superconducting state, is the expected incoherent Cooper-pair breaking peak (CPBP). At the highest measured pressure (9.5 GPa), the SC transition has already reached its maximum of 8.5 K [40]. By calculating the theoretical Raman response (purple line in Fig.…”

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confidence: 99%

Pressure-Induced Collapse of the Charge Density Wave and Higgs Mode Visibility in 2H−TaS2

et al. 2019

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The pressure evolution of the Raman active electronic excitations of the transition metal dichalcogenides 2H-TaS2 is followed through the pressure phase diagram embedding incommensurate chargedensity-wave and superconducting states. At high pressure, the charge-density-wave is found to collapse at 8.5 GPa. In the coexisting charge-density-wave and superconducting orders, we unravel a strong in-gap superconducting mode, attributed to a Higgs mode, coexisting with the expected incoherent Cooper-pair breaking signature. The latter remains in the pure superconducting state reached above 8.5 GPa. Our report constitutes the first observation of such Raman active Higgs mode since the longstanding unique case 2H-NbSe2.

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“…On the other hand, a different scenario for the interplay of CDW and SC is the occurrence of a superconducting dome on the edge of a CDW/structural instability, as proposed for T Se 2 (T = Ti, and Ta) [1,2,10,11], Lu(Pt 1−x Pd x ) 2 In [3], o-TaS 3 [12] and (Ca,Sr) 3 Ir 4 Sn 13 [13]. SC in conjunction with non-Fermi liquid behaviors is often found in close proximity to a magnetically ordered phase in strongly correlated electronic systems, such as heavy fermion compounds, high T c cuprates, and iron-based superconductors [14].…”

Section: Introductionmentioning

confidence: 99%

Evolution of charge density wave order and superconductivity under pressure in LaPt2Si2

Shen

et al. 2020

Phys. Rev. B

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We report measurements of the electrical resistivity and ac magnetic susceptibility of single crystalline LaPt2Si2 under pressure, in order to investigate the interplay of superconductivity and CDW order. LaPt2Si2 exhibits a first order phase transition from a tetragonal to orthorhombic structure, accompanied by the onset of CDW order below TCDW = 76 K, while superconductivity occurs at a lower temperature of Tc = 1.87 K. We find that the application of pressure initially suppresses the CDW transition, but enhances Tc. At pressures above 2.4 GPa, CDW order vanishes, while both Tc and the resistivity A-coefficient reach a maximum value around this pressure. Our results suggest that the occurrence of a superconducting dome can be accounted for within the framework of BCS theory, where there is a maximum in the density of states upon the closure of the CDW gap.

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Strong enhancement of superconductivity at high pressures within the charge-density-wave states of2H−TaS2and2H−TaSe2

Cited by 108 publications

References 58 publications

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

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

Pressure-Induced Collapse of the Charge Density Wave and Higgs Mode Visibility in 2H−TaS2

Evolution of charge density wave order and superconductivity under pressure in LaPt2Si2

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