Compressed H3S, Superfluid Density and the Quest for Room-Temperature Superconductivity

Tallon, J. L.; Talantsev, E. F.

doi:10.1007/s10948-017-4419-4

Cited by 8 publications

(8 citation statements)

References 32 publications

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“…Table III leaded us to an important finding that both nearroom-temperature superconductors have very large fluctuations of the order parameter amplitude, which, in some scenarios, have characteristic temperatures, Tfluc,amp, of only about 15% above observed transition temperature, Tc. This is similar to cuprates and pnictides which have large fluctuations of order parameter phase [57,62] (which causes the suppression of the observed Tc by about 30% from its mean-field value, − [57,62]).…”

Section: Thermodynamic Fluctuations In Compressed Lah10supporting

confidence: 63%

“…In our recent paper [14], we deduced (0) in H3S more accurately in comparison with values we used to calculate , ℎ and , in our previous papers [57,62]. By taking in account that H3S exhibits  = 88-105 [57,62,65], we revisited , ℎ and , at two applied pressures of P = 155 GPa and 160 GPa (Table III) To calculate , ℎ and , (Eqs. 36,37) for compressed LaH10 there is a need to make an assumption about the value for Ginzburg-Landau parameter, .…”

Section: Thermodynamic Fluctuations In Compressed Lah10mentioning

confidence: 91%

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Classifying hydrogen-rich superconductors

Talantsev

2019

Mater. Res. Express

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The era of near-room-temperature superconductivity started after experimental discovery by Drozdov et al (2015 Nature 525 73) who found that compressed H3S exhibits superconducting transition at Tc = 203 K. To date, the record near-room-temperature superconductivity stands with another hydrogen-rich highly compressed compound, LaH10 (Somayazulu et al 2019 Phys. Rev. Lett. 122 027001), which has critical temperature of > 240 . In this paper, we analyse available upper critical field, Bc2(T), data for LaH10 (Drozdov et al 2019 Nature 569 528) and report that this compound in all consideredscenarios has the ratio of Tc to the Fermi temperature, TF, 0.009 < Tc/TF < 0.038, which is typical range for unconventional superconductors. In attempt to extend our finding, we examined experimental Bc2(T) data for superconductors in the palladium-hydrogen (PdHx) and thorium-hydrogen-deiterium (ThH-ThD) systems and surprisingly find that superconductors in both these systems also fall into unconventional superconductors band.Taking in account that H3S has the ratio of 0.012 < Tc/TF < 0.039 (Talantsev 2019 Mod. Phys. Lett. B 33 1950195) we come to conclusion that in the Uemura plot all discovered to date hydrogen-rich superconductors, i.e. Th4H15-Th4D15, PdHx, H3S and LaH10 (in this list we do not include NbTiHx, PtHx, SiH4, and PH3 for which experimental data beyond Tc are unknown), lie in same band as all unconventional superconductors, particularly heavy

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Section: Thermodynamic Fluctuations In Compressed Lah10supporting

confidence: 63%

Section: Thermodynamic Fluctuations In Compressed Lah10mentioning

confidence: 91%

Classifying hydrogen-rich superconductors

Talantsev

2019

Mater. Res. Express

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“…As we mentioned in our previous papers [12,13,46,47], first principles calculations [39,48,49] always provide -values near 5, which is the very strong-coupling limit for s-wave symmetry (also note that other superconducting gap symmetries have weak-coupling limits of  ~ 5 [50][51][52]).…”

Section: Thh9 (P = 170 Gpa) In Uemura Plotmentioning

confidence: 66%

“…Semenok et al [44] reported the discovery of a high-temperature superconducting phase of ThH 9 at P=170 GPa which exhibits P6 3 /mmc crystallographic symmetry and superconducting transition temperature of T c =146 K. They also performed first principles calculations and deduced the effective mass in this superconductor: As we mentioned in our previous papers [12,13,46,47], first principles calculations [39,48,49] always provide α-values near 5, which is the very strong-coupling limit for s-wave symmetry (also note that other superconducting gap symmetries have weak-coupling limits of α∼5 [50][51][52]). Despite the orthodox view, several new, alternative, approaches were developed to explain NRT superconductivity in compressed hydrides: Hirsch and Marsiglio [53], Souza and Marsiglio [54], Harshman and Fiory [55], as well as Kaplan and Imry [56].…”

Section: Thh 9 (P=170 Gpa) In Uemura Plotmentioning

confidence: 89%

Classifying superconductivity in ThH-ThD superhydrides/superdeuterides

Talantsev

Mataira

2020

Mater. Res. Express

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Satterthwaite and Toepke (1970 Phys. Rev. Lett. 25 741) discovered that Th 4 H 15 -Th 4 D 15 superhydrides are superconducting but exhibit no isotope effect. As the isotope effect is a fundamental prediction of electron-phonon mediated superconductivity described by Bardeen, Cooper, and Schrieffer (BCS) its absence alludes to some other mechanism. Soon after this work, Stritzker and Buckel (1972 Zeitschrift für Physik A Hadrons and nuclei 257 1-8) reported that superconductors in the PdH x -PdD x system exhibit the reverse isotope effect. Yussouff et al (1995 Solid State Communications 94 549) extended this finding in PdH x -PdD x -PdT x systems. Renewed interest in hydrogen-and deuterium-rich superconductors is driven by the discovery of near-room-temperature superconductivity in highlycompressed H 3 S (Drozdov et al 2015 Nature 525 73) and LaH 10 (Somayazulu et al 2019 Phys. Rev. Lett. 122 027001).Here we attempt to reaffirm or disprove our primary idea that the mechanism for nearroom-temperature superconductivity in hydrogen-rich superconductors is not BCS electron-phonon mediated. To that end, we analyse the upper critical field data, B c2 (T), in Th 4 H 15 -Th 4 D 15 (Satterthwaite and Toepke 1970 Phys. Rev. Lett. 25 741) as well as two recently discovered highpressure hydrogen-rich phases of ThH 9 and ThH 10 (Semenok et al 2019 Materials Today,

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“…It should be noted, that as we already mentioned in our previous papers [15,16,37,38], that first principles calculations [31,35,36,[39][40][41] always provide -values near 5, which is the range of very strong-coupling limit for s-wave symmetry (it should be noted that other superconducting gap symmetries have weak-coupling limits of  ~ 5 [42][43][44]).…”

Section: Thh9 (P = 170 Gpa) In Uemura Plotmentioning

confidence: 85%

Classifying Superconductivity in ThH-ThD Superhydrides

Talantsev¹

2019

Preprint

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Satterthwaite and Toepke (1970 Phys. Rev. Lett. 25 741) discovered that Th4H15-Th4D15 superhydrides exhibit superconductivity and have no isotope effect. The latter is fundamental contradiction with the concept of electron-phonon mediated superconductivity of Bardeen-Cooper-Schrieffer (BCS) theory. Soon after this work, Stritzker and Buckel (1972 Zeitschrift für Physik A Hadrons and nuclei 257 1-8) reported that superconductors in PdHx-PdDx system exhibit reverse isotope effect. Yussouff et al (1995 Solid State Communications 94 549) extended this finding on PdHx-PdDx-PdTx system. Recent interest to hydrogen- and deuterium-rich superconductors is based on the discovery of near-room-temperature superconductivity in highly-compressed H3S (Drozdov et al. 2015 Nature 525 73) and LaH10 (Somayazulu et al 2019 Phys. Rev. Lett. 122 027001). To date, there is no clarity about isotope effect in H3S-D3S system, because thorough examination of available experimental data reported by Drozdov et al (2015 Nature 525 73) shows that H3S-D3S system perhaps has reverse isotope effect. In attempt to reaffirm/disprove our primary idea that the mechanism for near-room-temperature superconductivity in hydrogen-rich superconductors is not BCS electron-phonon interaction, we analyse the upper critical field data, Bc2(T), in Th4H15-Th4D15 phases (Satterthwaite and Toepke 1970 Phys. Rev. Lett. 25 741) and two recently discovered high-pressure hydrogen-rich phases of ThH9 and ThH10 (Semenok et al 2019 arXiv:1902.10206). As the result, it is found that all known to date thorium super-hydrides/deuterides are unconventional superconductors which have Tc/TF ratios within a range of 0.008 < Tc/TF < 0.120, where Tc is the superconducting transition temperature and TF is the Fermi temperature.

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Compressed H3S, Superfluid Density and the Quest for Room-Temperature Superconductivity

Cited by 8 publications

References 32 publications

Classifying hydrogen-rich superconductors

Classifying hydrogen-rich superconductors

Classifying superconductivity in ThH-ThD superhydrides/superdeuterides

Classifying Superconductivity in ThH-ThD Superhydrides

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