Hall effect of YBa2Cu3O7-δ single crystals

For a number of YBa2Cu3O7-delta single crystals with various oxygen concentrations and differing values of the zero magnetic-field critical temperature T-c0, the Hall effect has been investigated between 10 and 300 K by applying magnetic fields H parallel to c and currents I perpendicular to c, where c denotes the direction perpendicular to the Cu-O planes of this material. These measurements yield that the sign change of the Hall voltage close to T-c0 varies with delta and eventually disappears in heavily oxygen-depleted YBa2Cu3O7-delta single crystals. Such behavior can qualitatively be explained by a model calculation based on the time-dependent Ginsburg-Landau theory. In the normal state, we find that the Hall coefficient R-H and the Hall angle theta(H) vary as R(H)(-1)proportional to T and cot theta(H) proportional to T-2 in an extended temperature range, as has previously been found for fully oxygenated YBa2Cu3O7 and YBa2Cu3-yMyO7 (M = Ni, Zn). Deviations from these behaviors for both R-H(-1) and cot theta(H) are observed below a characteristic temperature T*, whereby T* increases with decreasing T-c0, i.e., increasing oxygen depletion. This implies a temperature-induced variation of the normal-slate electronic spectrum and/or the scattering parameters governing the electronic transport of this material.