Systematic variation of magnetic-field penetration depth in high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>superconductors studied by muon-spin relaxation

Uemura, Yohei; Emery, V. J.; Moodenbaugh, A. R.; Suenaga, M.; Johnston, D. C.; Jacobson, Allan J.; Lewandowski, J. T.; Brewer, J. H.; Kiefl, R. F.; Kreitzman, S. R.; Luke, G. M.; Riseman, T. M.; Stronach, C. E.; Kossler, W. J.; Kempton, J. R.; Yu, Xiao-Dong; Opie, D.; Schone, H. E.

doi:10.1103/physrevb.38.909

“…Consequently, an effective Fermi temperature can be calculated using the relation k B T F = (h 2 /2)(3π 2 n s ) 2/3 /m * . The results of following this procedure are displayed in Table II. Uemura et al have described a method of classifying superconductors based on the ratio of the critical temperature T c to the effective Fermi temperature T F , which is found to be 1/414 and 1/304 for the Lu and Y compounds, respectively [26][27][28]. This places the ternary borides in the vicinity of the "band of unconventionality" described by Uemura, as depicted in Fig.…”

Section: B Transverse-field Muon-spin Rotationmentioning

confidence: 97%

Probing the superconducting ground state of the rare-earth ternary boride superconductors RRuB2 ( R= Lu,Y) using muon-spin rotation and relaxation

Barker

¹

,

Singh

²

,

Hillier

³

et al. 2018

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Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher statement: © 2018 American Physical Society A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription. The superconductivity in the rare-earth transition-metal ternary borides RRuB 2 (where R = Lu and Y) has been investigated using muon-spin rotation and relaxation. Measurements made in zero field suggest that time-reversal symmetry is preserved upon entering the superconducting state in both materials; a small difference in depolarization is observed above and below the superconducting transition in both compounds, however, this has been attributed to quasistatic magnetic fluctuations. Transverse-field measurements of the flux-line lattice indicate that the superconductivity in both materials is fully gapped, with a conventional s-wave pairing symmetry and BCS-like magnitudes for the zero-temperature gap energies. The electronic properties of the charge carriers in the superconducting state have been calculated, with effective masses m * /m e = 9.8 ± 0.1 and 15.0 ± 0.1 in the Lu and Y compounds, respectively, with superconducting carrier densities n s = (2.73 ± 0.04) × 10 28 m −3 and (2.17 ± 0.02) × 10 28 m −3 . The materials have been classified according to the Uemura scheme for superconductivity, with values for T c /T F of 1/(414 ± 6) and 1/(304 ± 3), implying that the superconductivity may not be entirely conventional in nature.

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“…It has been observed that the high-T c , organic, heavy-fermion, and other unconventional superconductors lie in the range 0.01 T c /T F 0.1 [59][60][61]. However, Re 6 Zr lies outside of the range for unconventional superconductivity, supporting the view that the superconducting mechanism is primarily conventional.…”

Section: F Properties Of the Superconducting Statementioning

confidence: 99%

Superconducting and normal-state properties of the noncentrosymmetric superconductorRe6Zr

Mayoh

¹

,

Barker

²

,

Singh

³

et al. 2017

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We systematically investigate the normal and superconducting properties of noncentrosymmetric Re 6 Zr using magnetization, heat capacity, and electrical resistivity measurements. Resistivity measurements indicate Re 6 Zr has poor metallic behavior and is dominated by disorder. Re 6 Zr undergoes a superconducting transition at T c = (6.75 ± 0.05) K. Magnetization measurements give a lower critical field, μ 0 H c1 = (10.3 ± 0.1) mT. The Werthamer-Helfand-Hohenberg model is used to approximate the upper critical field μ 0 H c2 = (11.2 ± 0.2) T, which is close to the Pauli limiting field of 12.35 T and which could indicate singlet-triplet mixing. However, low-temperature specific-heat data suggest that Re 6 Zr is an isotropic, fully gapped s-wave superconductor with enhanced electron-phonon coupling. Unusual flux pinning resulting in a peak effect is observed in the magnetization data, indicating an unconventional vortex state.

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“…Consequently an effective Fermi temperature T F = 432 ± 8 K may be calculated. Uemura et al have described a method of classifying superconductors based on the ratio of the critical temperature to this effective Fermi temperature, which for this system is T c /T F = 1/192 [36][37][38]. This places La 7 Ir 3 in the vicinity of the heavy fermion superconductors, which is reflected in the relatively large value of m * .…”

mentioning

confidence: 99%

Unconventional Superconductivity inLa7Ir3Revealed by Muon Spin Relaxation: Introducing a New Family of Noncentrosymmetric Superconductor That Breaks Time-Reversal Symmetry

Barker

¹

,

Singh

²

,

Thamizhavel

³

et al. 2015

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Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. The superconductivity of the noncentrosymmetric compound La7Ir3 has been investigated using muon spin rotation and relaxation (µSR). Zero-field measurements reveal the presence of spontaneous static or quasi-static magnetic fields below the superconducting transition temperature Tc = 2.25 K -a clear indication that the superconducting state breaks time-reversal symmetry. Furthermore, transverse-field rotation measurements suggest that the superconducting gap is isotropic, and that the pairing symmetry of the superconducting electrons is predominantly s-wave with an enhanced binding strength. The results indicate that the superconductivity in La7Ir3 may be unconventional, and paves the way for further studies of this family of materials. Publisher

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Systematic variation of magnetic-field penetration depth in high-Tcsuperconductors studied by muon-spin relaxation

Cited by 204 publications

References 28 publications

Probing the superconducting ground state of the rare-earth ternary boride superconductors RRuB2 ( R= Lu,Y) using muon-spin rotation and relaxation

Probing the superconducting ground state of the rare-earth ternary boride superconductors RRuB2 ( R= Lu,Y) using muon-spin rotation and relaxation

Superconducting and normal-state properties of the noncentrosymmetric superconductorRe6Zr

Unconventional Superconductivity inLa7Ir3Revealed by Muon Spin Relaxation: Introducing a New Family of Noncentrosymmetric Superconductor That Breaks Time-Reversal Symmetry

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