1
|
Das D, Gupta R, Baines C, Luetkens H, Kaczorowski D, Guguchia Z, Khasanov R. Unconventional Pressure Dependence of the Superfluid Density in the Nodeless Topological Superconductor α-PdBi_{2}. PHYSICAL REVIEW LETTERS 2021; 127:217002. [PMID: 34860073 DOI: 10.1103/physrevlett.127.217002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
We investigated the superconducting properties of the topological superconductor α-PdBi_{2} at ambient and external pressures up to 1.77 GPa using muon spin rotation experiments. The ambient pressure measurements evince a fully gapped s-wave superconducting state in the bulk of the specimen. Alternating current magnetic susceptibility and muon spin rotation measurements manifest a continuous suppression of T_{c} with increasing pressure. In parallel, we observed a significant decrease of superfluid density by ∼20% upon application of external pressure. Remarkably, the superfluid density follows a linear relation with T_{c}, which was found before in some unconventional topological superconductors and hole-doped cuprates. This finding signals a possible crossover from Bose-Einstein to Bardeen-Cooper-Schrieffer like condensation in α-PdBi_{2}.
Collapse
Affiliation(s)
- Debarchan Das
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Ritu Gupta
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Christopher Baines
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Hubertus Luetkens
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Dariusz Kaczorowski
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław, ul. Okólna 2, 50-422, Poland
| | - Zurab Guguchia
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Rustem Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| |
Collapse
|
2
|
Di Castro D, Khasanov R, Shengelaya A, Conder K, Jang DJ, Park MS, Lee SI, Keller H. Comparative study of the pressure effects on the magnetic penetration depth in electron- and hole-doped cuprate superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:275701. [PMID: 21828498 DOI: 10.1088/0953-8984/21/27/275701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The effect of pressure on the magnetic penetration depth λ was tested for the hole-doped superconductor YBa(2)Cu(3)O(7-δ) and in the electron-doped one Sr(0.9)La(0.1)CuO(2) by means of magnetization measurements. Whereas a large change of λ was found in YBa(2)Cu(3)O(7-δ), confirming the non-adiabatic character of the electron-phonon coupling in hole-doped superconductors, the same quantity is not affected by pressure in electron-doped Sr(0.9)La(0.1)CuO(2), suggesting a close similarity of the latter to conventional adiabatic Bardeen-Cooper-Schrieffer superconductors. The present results imply a remarkable difference between the electronic properties of hole-doped cuprates and electron-doped Sr(0.9)La(0.1)CuO(2), giving a strong contribution to the long debated asymmetric consequences of hole and electron doping in cuprate superconductors.
Collapse
Affiliation(s)
- D Di Castro
- CNR-INFM-Coherentia and Dipartimento di Ingegneria Meccanica, Universita' di Roma 'Tor Vergata', Via del Politecnico 1, I-00133 Roma, Italy
| | | | | | | | | | | | | | | |
Collapse
|
3
|
Shimojima T, Shibata Y, Ishizaka K, Kiss T, Chainani A, Yokoya T, Togashi T, Wang XY, Chen CT, Watanabe S, Yamaura J, Yonezawa S, Muraoka Y, Hiroi Z, Saitoh T, Shin S. Interplay of superconductivity and rattling phenomena in beta-pyrochlore KOs2O6 studied by photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2007; 99:117003. [PMID: 17930463 DOI: 10.1103/physrevlett.99.117003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Indexed: 05/25/2023]
Abstract
The electronic structure near the Fermi level (EF) of the beta-pyrochlore superconductor KOs2O6 is studied using laser-excited ultrahigh-resolution photoemission spectroscopy. The superconducting gap clearly opens across the superconducting transition (Tc=9.6 K), with the strong electron-phonon coupling value of 2Delta(0)/k B Tc>or=4.56. A fitting analysis identifies clear anomalies at Tp=7.5 K in the temperature dependencies of the superconducting gap size and the quasiparticle relaxation lifetime. These anomalies and the fine spectral structures arising from phonons suggest that the existence of the rattling behavior of K ions significantly affects the superconductivity in KOs2O6.
Collapse
Affiliation(s)
- T Shimojima
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Bonalde I, Ribeiro R, Brämer-Escamilla W, Yamaura J, Nagao Y, Hiroi Z. Isotropically gapped strong-coupling superconductivity in the beta-pyrochlore KOs2O6: evidence from penetration depth measurements. PHYSICAL REVIEW LETTERS 2007; 98:227003. [PMID: 17677873 DOI: 10.1103/physrevlett.98.227003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2007] [Indexed: 05/16/2023]
Abstract
We report on measurements of the temperature dependence of the magnetic penetration depth down to 0.04 K in a high-quality sample of the beta-pyrochlore KOs2O6 (Tc=9.65 K) with a spin-frustrated lattice. We observe temperature-independent behavior below T approximately 0.3Tc, which is firm evidence for the presence of an isotropic superconducting gap in this material. In the whole temperature range the superfluid density is very well described, without the need of adjustable parameters, by a strong-coupling extension of the BCS model for an isotropic gap. Thus, the penetration depth results indicate that KOs2O6 is a strong-coupling superconductor with a fully developed energy gap. No effect of the second phase transition taking place at Tp=7.5 K was observed on the penetration depth, which suggests that the Cooper pairs remain unperturbed across this transition.
Collapse
Affiliation(s)
- I Bonalde
- Centro de Física, Instituto Venezolano de Investigaciones Científicas, Apartado 21874, Caracas 1020-A, Venezuela
| | | | | | | | | | | |
Collapse
|
5
|
Khasanov R, Häfliger PS, Shitsevalova N, Dukhnenko A, Brütsch R, Keller H. Effect of pressure on the Ginzburg-Landau parameter kappa=lambda/xi in YB6. PHYSICAL REVIEW LETTERS 2006; 97:157002. [PMID: 17155351 DOI: 10.1103/physrevlett.97.157002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Indexed: 05/12/2023]
Abstract
Measurements of the transition temperature Tc, the upper critical field Hc2, and the magnetic penetration depth lambda under hydrostatic pressure (up to approximately 9.2 kbar) in the YB6 superconductor were carried out. A pronounced and negative pressure effect (PE) on Tc and Hc2 with dTc/dp=-0.0547(4) K/kbar and micro0dHc2(0)/dp=-4.84(20) mT/kbar, and zero PE on lambda(0) were observed. The PE on the coherence length dxi(0)/dp=0.28(2) nm/kbar was calculated from the measured pressure dependence of Hc2(0). Together with the zero PE on the magnetic penetration depth lambda(0), our results imply that the Ginzburg-Landau parameter kappa(0)=xi(0)/lambda(0) depends on pressure and that pressure "softens" YB6, e.g., moves it to the type-I direction.
Collapse
Affiliation(s)
- R Khasanov
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | | | | | | | | | | |
Collapse
|
6
|
Kasahara Y, Shimono Y, Shibauchi T, Matsuda Y, Yonezawa S, Muraoka Y, Hiroi Z. Thermal conductivity of the pyrochlore superconductor KOs2O6: strong electron correlations and fully gapped superconductivity. PHYSICAL REVIEW LETTERS 2006; 96:247004. [PMID: 16907273 DOI: 10.1103/physrevlett.96.247004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Indexed: 05/11/2023]
Abstract
To elucidate the nature of the superconducting ground state of the geometrically frustrated pyrochlore KOs2O6 (Tc=9.6 K), the thermal conductivity was measured down to low temperatures (approximately Tc/100). We found that the quasiparticle mean free path is strikingly enhanced below a transition at Tp=7.8 K, indicating enormous electron inelastic scattering in the normal state. In magnetic fields, the conduction at T-->0 K is nearly constant up to approximately 0.4Hc2, in contrast with the rapid growth expected for superconductors with an anisotropic gap. This unambiguously indicates a fully gapped superconductivity, in contrast with previous studies. These results highlight that KOs2O6 is unique among superconductors with strong electron correlations.
Collapse
Affiliation(s)
- Y Kasahara
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | | | | | | | | | | | | |
Collapse
|
7
|
Muramatsu T, Takeshita N, Terakura C, Takagi H, Tokura Y, Yonezawa S, Muraoka Y, Hiroi Z. Anomalous pressure dependence of the superconducting transition temperature of beta-pyrochlore AOs2O6 oxides. PHYSICAL REVIEW LETTERS 2005; 95:167004. [PMID: 16241835 DOI: 10.1103/physrevlett.95.167004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Indexed: 05/05/2023]
Abstract
High-pressure effects on the superconducting transitions of beta-pyrochlore oxide superconductors AOs(2)O(6) (A = Cs,Rb,K) are studied by measuring resistivity under high pressures up to 10 GPa. The superconducting transition temperature T(c) first increases with increasing pressure in every compound and then exhibits a broad maximum at 7.6 K (6 GPa), 8.2 K (2 GPa), and 10 K (0.6 GPa) for A = Cs, Rb, and K, respectively. Finally, the superconductivity is suppressed completely at a critical pressure near 7 GPa and 6 GPa for A = Rb and K and probably above 10 GPa for A = Cs. Characteristic changes in the coefficient A of the T(2) term in resistivity and residual resistivity are observed, both of which are synchronized with the corresponding change in T(c).
Collapse
Affiliation(s)
- T Muramatsu
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, Japan
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Schneider T, Khasanov R, Keller H. Evidence for charged critical behavior in the pyrochlore superconductor RbOs2O6. PHYSICAL REVIEW LETTERS 2005; 94:077002. [PMID: 15783843 DOI: 10.1103/physrevlett.94.077002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2004] [Indexed: 05/24/2023]
Abstract
We analyze magnetic penetration depth (lambda) data of the recently discovered superconducting pyrochlore oxide RbOs(2)O(6). Our results strongly suggest that in RbOs(2)O(6) charged critical fluctuations dominate the temperature dependence of lambda near T(c). This is in contrast with the mean-field behavior observed in conventional superconductors and the uncharged critical behavior found in nearly optimally doped cuprate superconductors. However, this finding agrees with the theoretical predictions for charged criticality and the charged criticality observed in underdoped YBa(2)Cu(3)O(6.59).
Collapse
Affiliation(s)
- T Schneider
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | | | | |
Collapse
|