Superconducting diamagnetic fluctuations in MgB2
A. Lascialfari, T. Mishonov, A. Rigamonti, P. Tedesco, A. Varlamov
DOI 10.1103/PhysRevB.65.180501 · Physical Review B
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Abstract
The fluctuating diamagnetic magnetization Mfl at a constant field H as a function of temperature and the isothermal magnetization Mfl vs H are measured in MgB2, above the superconducting transition temperature. The expressions for Mfl in randomly oriented powders are derived in the Gaussian approximation of local Ginzburg-Landau theory and used for the analysis of the data. The scaled magnetization −Mfl/H1/2T is found to be field dependent. In the limit of evanescent field the behavior for Gaussian fluctuations is obeyed while for H≳100 Oe the field tends to suppress the fluctuating pairs, with a field dependence of Mfl close to the one expected when short-wavelength fluctuations and nonlocal electrodynamic effects are taken into account. Our data, besides providing the isothermal magnetization curves for T>Tc(0) in a BCS-type superconductor such as MgB2, evidence an enhancement of the fluctuating diamagnetism, which is related to the occurrence in this new superconductor of an anisotropic spectrum of the superconducting fluctuations.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 39.07 | Pressure not reported | unknown |
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