| 1. |
- Khasanov, Rustem, et al.
(author)
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Superconducting nature of the Bi-II phase of elemental bismuth
- 2019
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In: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 99:17
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Journal article (peer-reviewed)abstract
- The superconductivity in the Bi-II phase of elemental bismuth (transition temperature T-c similar or equal to 3.92 K at pressure p similar or equal to 2.80 GPa) was studied experimentally by means of the muon-spin rotation as well as theoretically by using the Eliashberg theory in combination with density functional theory calculations. Experiments reveal that Bi-II is a type-I superconductor with a zero temperature value of the thermodynamic critical field B-c(0) similar or equal to 31.97 mT. The Eliashberg theory approach provides a good agreement with the experimental T-c and the temperature evolution of B-c . The estimated value for the retardation (coupling) parameter k(B)T(c)/omega(In) approximate to 0.07 (omega(In) is the logarithmically averaged phonon frequency) suggests that Bi-II is an intermediately coupled superconductor.
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| 2. |
- Khasanov, Rustem, et al.
(author)
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Superconductivity of Bi-III phase of elemental bismuth : Insights from muon-spin rotation and density functional theory
- 2018
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In: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 98:14
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Journal article (peer-reviewed)abstract
- Using muon-spin rotation the pressure-induced superconductivity in the Bi-III phase of elemental bismuth (transition temperature T-c similar or equal to 7.05 K) was investigated. A Ginzburg-Landau parameter kappa = lambda/xi = 30(6) (lambda is the magnetic penetration depth, xi is the coherence length) was estimated, which turns out to be the highest among known single element superconductors. The temperature dependence of the superconducting energy gap [Delta(T)] reconstructed from lambda(-2)(T) deviates from the weakly coupled BCS prediction. The coupling strength 2 Delta/k(B)T
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| 3. |
- Menkveld, Albert J., et al.
(author)
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Nonstandard Errors
- 2024
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In: JOURNAL OF FINANCE. - : Wiley-Blackwell. - 0022-1082 .- 1540-6261. ; 79:3, s. 2339-2390
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Journal article (peer-reviewed)abstract
- In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty-nonstandard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for more reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants.
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| 4. |
- Sassa, Yasmine, et al.
(author)
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Investigation of the Magnetic Properties of Na0.7CoO2 Prepared by Electrochemical Reaction
- 2018
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In: JPS Conf. Proc. 21, 011019 (2018) [5 pages] Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017). - : Physical Society of Japan.
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Conference paper (peer-reviewed)abstract
- We report a muon spin rotation and relaxation (μ+SR) study on Na0.7CoO2 powder samples, where the sodium (Na) has been intercalated via an electrochemical reaction inside a Na-ion battery. The zero field μ+SR measurement at T = 2 K shows a paramagnetic state for the as-grown sample whereas an antiferromagnetic (AF) ordered state is seen for the electrochemically cycled one. Furthermore, the temperature dependence of the muon-spin precession frequencies reveals a Néel transition temperature of TN = 22 K. The results demonstrate the importance of having high-quality homogenous samples, and put the existing NaxCoO2 magnetic phase diagram under debate.
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| 5. |
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| 6. |
- Sugiyama, Jun, et al.
(author)
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Unveiled magnetic transition in Na battery material : mu+SR study of P2-Na0.5VO2
- 2015
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:24, s. 18531-18537
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Journal article (peer-reviewed)abstract
- We have investigated the microscopic magnetic nature of a novel Na battery material, P2-Na0.5VO2, in which V ions form a two-dimensional triangular lattice, by means of muon-spin rotation and relaxation (mu+SR) measurements down to 50 mK. Although magnetization measurements indicated the presence of an antiferromagnetic transition at 13 K, the internal magnetic field due to the formation of magnetic order appears not at 13 K but at 2 K. Furthermore, the magnetic order is found to have a wide field distribution even at 50 mK. Such wide field distribution is reasonably explained by a combination of multiple muon sites and the formation of a long-range magnetic order, while the reliable spin structure is still unknown.
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