Comment on “Superconducting state of Ca-VII below a critical temperature of 29 K at a pressure of 216 GPa”
M. Andersson
DOI 10.1103/PhysRevB.84.216501 · Physical Review B
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Abstract
In a recent paper, Sakata et al. [Phys. Rev. B 83, 220512(R) (2011)] report on superconductivity at 29 K in Ca under high pressure. Here, I argue that their method to define the onset of the superconducting transition temperature from resistivity measurements is misleading and that the correct value for the onset of the transition based on resistivity data shown in their paper should be 21 K. The discrepancy between these two temperatures is explained by superconducting fluctuations occurring at temperatures above the superconducting transition temperature.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Ca Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 29 | 216 GPa | onset |
| Ca Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 21 | 216 GPa | onset |
| Ca Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 20.5 | 216 GPa | midpoint |
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