High-Field Galvanomagnetic Properties of Niobium and Tantalum

The galvanomagnetic properties of niobium and tantalum were measured at 4.2\ifmmode^\circ\else\textdegree\fi{}K in fields up to 100 kG for single crystals having residual resistivity ratios of 1500 (niobium) and \ensuremath{\sim}10 000 (tantalum). The two metals exhibit very similar anisotropy of their galvanomagnetic properties. Each is uncompensated, with a net number of carriers equal to one hole per atom. The strong anisotropy of the magnetoresistance results from open orbits on a surface which is topologically similar to a set of intersecting cylinders along the cube axes. Measurements of the Hall coefficient with the field along the symmetry axes show this to be an open hole surface, and provide a measure of two of its dimensions. This surface is consistent with that proposed by Mattheiss for the group-VB metals on the basis of his energy-band calculations for tungsten.

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