THE TEMPERATURE VARIATION OF THE GINZBURG-LANDAU PARAMETER IN NIOBIUM SINGLE CRYSTALS.
MASSACHUSETTS INST OF TECH CAMBRIDGE
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Magnetization measurements were made on high purity Nb single crystals at temperature from 1.6 to 8.8K. The crystals were grown by the electron beam floating-zone technique and had resistivity ratios from 100 to 800. The upper and lower critical fields Hsub c2 and Hsubc1 and the slope of the magnetization curve at the upper critical field, Hsubc2, were determined. The value of Hsubc2 and the slope at Hsubc2 require two separate phenomenological parameters, as has been predicted by the Maki-Tsuzuki linear approximation. The temperature dependence of the slope at Hsubc2 is best described by the Maki-Tsuzuki theory, but the temperature variation of Hsubc2 is best described by the Ginzburg-Bardeen theory. Author
- Electricity and Magnetism