Hall effect in Zn-doped YBa2Cu3O7-delta revisited: Hall angle and the pseudogap

The temperature dependence of the Hall coefficient is measured with high ac curacy in a series of YBa2(Cu1-zZnz)(3)O-6.78 crystals with 0 less than or equal to z less than or equal to 0.013. We found that-the cotangent of the Hall angle, cot theta(H), starts to deviate upward from the T-2 dependence below T-0 (similar to 130 K); regardless of the Zn concentration. We discus s that this deviation is caused by the pseudogap; the direction of the devi ation and its insensitivity to the Zn doping suggest that the pseudogap aff ects cot theta(H) through a change in the effective mass, rather than throu gh a change in the Hall scattering rate. [S0163-1829(99)50346-9].