Phenomenology and sign change of the Hall resistivity near the superconducting transition of polycrystalline DyBa2Cu3O7-δ

Measurements of the temperature dependence of the electrical resistivity and the Hall effect in the normal and superconducting states of a ceramic DyBa2Cu3O7-delta superconductor are reported. In high temperatures the diagonal resistivity is proportional to T, whereas the Hall response exhibits a 1/T dependence and the cotangent of the Hall angle is proportional to T-2. Upon decreasing the temperature, the Hall response shows a sign reversal close to T-c, goes through a negative maximum and vanishes close to the so-called zero-resistance temperature. The aim of this report is to show that the sign change occurs in the temperature region dominated by thermal fluctuations in the order parameter.