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Maisuradze, A.; Shengelaya, А.; Amato, A.; Pomjakushina, E.; Keller, H.

doi:10.1103/physrevb.84.184523

Cited by 37 publications

(74 citation statements)

References 58 publications

(119 reference statements)

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Section: Discussion Pressure Dependence Of Superconducting Parametersmentioning

confidence: 99%

“…Also in the multigap superconductor MgB 2 , which is a moderately strong electron-phonon mediated superconductor, the two gap-to-T c ratios are practically pressure independent and only a small pressure effect of λ(0) has been observed [41]. No or small pressure dependence of λ (0) −2 has been reported also in some unconventional superconductors, such as the electron doped infinite layer cuprate Sr 0.9 La 0.1 CuO 2 [42] or the nearly optimally hole doped YBaCu 3 O 7−δ [27].In the (Ca 1−x Sr x ) 3 Ir 4 Sn 13 system, the positive variation of the critical temperature with pressure is a clear indication of the importance of the electronic contribution, such as a change of N (E F ). The observed pressure induced enhancement of the superfluid density is very high, with a relative variation between the lowest (0.15 GPa) and the highest (2.18 GPa) measured pressures ∆λ (0) −2 /λ(0) −2 ≃ 240%.…”

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confidence: 99%

“…The temperature dependence of λ −2 is a measure of the superfluid density λ −2 ∝ ρ s ≡ ns m * (where n s is the supercarrier density and m * effective mass), whereas the low-temperature behavior of λ(T ) reflects the superconducting gap structure. Despite the importance of the evolution of this quantity in understanding the nature of superconductivity, especially around a zero temperature quantum transition, there are not many measurements on the pressure dependence on λ and only a small number of µSR studies on the effect of pressure have been reported so far [25][26][27].Here we observe a pronounced increase of the superfluid density that sets in at a pressure p c ≈ 1.6 GPa with a sudden enhancement of the superconducting gap value, indicating that a QCP exist in the superconducting state leading to a significant enhancement of the superconducting pairing strength when the CDW is suppressed. We find that Ca 3 Ir 4 Sn 13 remains a conventional electron-phonon coupled s-wave superconductor across the quantum phase transition.…”

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confidence: 99%

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Strong enhancement ofs-wave superconductivity near a quantum critical point ofCa3Ir4Sn13

et al. 2015

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We report microscopic studies by muon spin rotation/relaxation as a function of pressure of the Ca3Ir4Sn13 and Sr3Ir4Sn13 cubic compounds, which are members of the (Ca1−xSrx)3Ir4Sn13 system displaying superconductivity and a structural phase transition associated with the formation of a charge density wave (CDW). We find a strong enhancement of the superfluid density and a dramatic increase of the pairing strength above a pressure of ≈ 1.6 GPa giving direct evidence of the presence of a quantum critical point separating a superconducting phase coexisting with CDW from a pure superconducting phase. The superconducting order parameter in both phases has the same s-wave symmetry. In spite of the conventional phonon-mediated BCS character of the weakly correlated (Ca1−xSrx)3Ir4Sn13 system, the dependence of the effective superfluid density on the critical temperature puts this compound in the "Uemura" plot close to unconventional superconductors. This system exemplifies that conventional BCS superconductors in the presence of competing orders or multi-band structure can also display characteristics of unconventional superconductors. INTRODUCTIONThe interplay between different electronic ground states is one of the fundamental topics in condensed matter physics and is well apparent in phase diagrams as a function of doping, pressure or magnetic fields, resulting in various forms of coexistence, cooperation or competition of the order parameters [1][2][3][4]. Particularly interesting are the regions at phase boundaries or at quantum critical points (QCPs) where different quantum states meet [5]. Very often magnetism and superconductivity are involved and, in spite of diverse structural and physical properties, many compounds show characteristic phase diagrams where superconductivity is found in the vicinity of electronic instabilities of magnetic (mainly antiferromagnetic) origin. In this case spin fluctuations are predominantly considered at the heart of the mechanisms leading to pairing and superconductivity is unconventional. Less common is the case where the electronic instability is linked to the formation of a charge density wave (CDW), which is based on the same electron-phonon interaction found in conventional superconductors.Ternary intermetallic stannide compounds such as R 3 T 4 Sn 13 , where R =La, Ca, Sr and T =Ir, Rh [6,7] are of particular interest because they exhibit many physical properties such as superconductivity, magnetic or charge order, and structural instabilities. The quasiskutteridite cubic superconductor (Ca,Sr) 3 Ir 4 Sn 13 and the related (Ca,Sr) 3 Rh 4 Sn 13 have recently attracted attention because of the presence of a pressure induced structural phase transition at a temperature T * , the possible coexistence of superconducting and charge density wave states, and a putative quantum critical point [8][9][10][11][12][13][14][15][16]. The role and interplay of these degrees of freedom remain a central issue also in many unconventional superconductors, as demonstrated by the recent observa...

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Section: Discussion Pressure Dependence Of Superconducting Parametersmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Strong enhancement ofs-wave superconductivity near a quantum critical point ofCa3Ir4Sn13

et al. 2015

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“…As shown previously 73 , the diamagnetism of the SC sample has an influence on the pressure cell signal, leading to the temperature dependent σ pc below T c . In order to consider the influence of the diamagnetic moment of the sample on the pressure cell 73 we assume the linear coupling between σ pc and the field shift of the internal magnetic field in the SC state:…”

Section: A Magnetization and Specific Heat Capacity Experimentsmentioning

confidence: 99%

Probing the pairing symmetry in the over-doped Fe-based superconductorBa0.35Rb0.65Fe2As2as a function of hydrostatic pressure

et al. 2016

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Probing the pairing symmetry in the over-doped Fe- We report muon spin rotation experiments on the magnetic penetration depth λ and the temperature dependence of λ −2 in the over-doped Fe-based high-temperature superconductor (Fe-HTS) Ba1−xRbxFe2As2 (x = 0.65) studied at ambient and under hydrostatic pressures up to p = 2.3 GPa. We find that in this system λ −2 (T ) is best described by d-wave scenario. This is in contrast to the case of the optimally doped x = 0.35 system which is known to be a nodeless s +− -wave superconductor. This suggests that the doping induces the change of the pairing symmetry from s +− to d-wave in Ba1−xRbxFe2As2. In addition, we find that the d-wave order parameter is robust against pressure, suggesting that d is the common and dominant pairing symmetry in over-doped Ba1−xRbxFe2As2. Application of pressure of p = 2.3 GPa causes a decrease of λ(0) by less than 5 %, while at optimal doping x = 0.35 a significant decrease of λ(0) was reported. The superconducting transition temperature Tc as well as the gap to Tc ratio 2∆/kBTc show only a modest decrease with pressure. By combining the present data with those previously obtained for optimally doped system x = 0.35 and for the end member x = 1 we conclude that the SC gap symmetry as well as the pressure effects on the SC quantities strongly depend on the Rb doping level. These results are discussed in the light of the putative Lifshitz transition, i.e., a disappearance of the electron pockets in the Fermi surface of Ba1−xRbxFe2As2 upon hole doping.

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“…However, in the presence of a FM material this signal is altered by the stray fields from the sample. The details of the more complex PC calibration for FM samples is described elsewhere [30,39]. Additional ZF-µSR measurements are performed at the lowbackground spectrometer Dolly (πE1 beamline) and are used exclusively as parameter constraints for the fits of equation 1.…”

Section: Methodsmentioning

confidence: 99%

Effect of external pressure on the magnetic properties of R CoAsO ( R =La, Pr, Sm): a μSR study

Prando

Sanna

Khasanov

et al. 2015

Journal of Physics and Chemistry of Solids

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We report on a detailed investigation of the itinerant ferromagnets LaCoAsO, PrCoAsO and SmCoAsO performed by means of muon spin spectroscopy upon the application of external hydrostatic pressures p up to 2.4 GPa. These materials are shown to be magnetically hard in view of the weak dependence of both critical temperatures T C and internal fields at the muon site on p. In the cases R = La and Sm, the behaviour of the internal field is substantially unaltered up to p = 2.4 GPa. A much richer phenomenology is detected in PrCoAsO instead, possibly associated with a strong p dependence of the statistical population of the two different crystallographic sites for the muon. Surprisingly, results are notably different from what is observed in the case of the isostructural compounds RCoPO, where the full As/P substitution is already inducing a strong chemical pressure within the lattice but p is still very effective in further affecting the magnetic properties.

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Muon spin rotation investigation of the pressure effect on the magnetic penetration depth in YBa2Cu3Ox

Cited by 37 publications

References 58 publications

Strong enhancement ofs-wave superconductivity near a quantum critical point ofCa3Ir4Sn13

Strong enhancement ofs-wave superconductivity near a quantum critical point ofCa3Ir4Sn13

Probing the pairing symmetry in the over-doped Fe-based superconductorBa0.35Rb0.65Fe2As2as a function of hydrostatic pressure

Effect of external pressure on the magnetic properties of R CoAsO ( R =La, Pr, Sm): a μSR study

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