HALL-EFFECT OF YBA2CU3O7-DELTA SINGLE-CRYSTALS

For a number of YBa2Cu3O7-delta single crystals with various oxygen co ncentrations 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 perp endicular to c, where c denotes the direction perpendicular to the Cu- O planes of this material. These measurements yield that the sign chan ge 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 b ased 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) va ry as R(H)(-1)proportional to T and cot theta(H) proportional to T-2 i n an extended temperature range, as has previously been found for full y 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-in duced variation of the normal-slate electronic spectrum and/or the sca ttering parameters governing the electronic transport of this material .