Determination of superconducting anisotropy from magnetization data on random powders as applied to LuNi2B2C, YNi2B2C, and MgB2
S. L. Bud’ko, V. G. Kogan, P. C. Canfield
DOI 10.1103/PhysRevB.64.180506 · Physical Review B
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Abstract
The recently discovered intermetallic superconductor MgB2 appears to have a highly anisotopic upper critical field with Hc2max/Hc2min≡γ>5. In order to determine the temperature dependence of both Hc2max and Hc2min we propose a method of extracting the superconducting anisotropy from the magnetization M(H,T) of randomly oriented powder samples. The method is based on two features in (∂M/∂T)H: the onset of diamagnetism at Tcmax, that is commonly associated with Hc2, and a kink in ∂M/∂T at a lower temperature Tcmin. Results for LuNi2B2C and YNi2B2C powders are in agreement with anisotropic Hc2 obtained from magnetotransport measurements on single crystals. Using this method on four different types of MgB2 powder samples we are able to determine Hc2max(T) and Hc2min(T) with γ≈6.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| LuNi2B2C Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 16.6 | Pressure not reported | onset |
| LuNi2B2C Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 16.6 | Pressure not reported | onset |
| YNi2B2C Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 15.5 | Pressure not reported | onset |
| YNi2B2C Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 15.5 | Pressure not reported | onset |
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 40 | Pressure not reported | onset |
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