Zeeman Effect on Magnetoresistance in High-Temperature Superconductors

The Zeeman effect on the magnetoresistance in high-temperature superconductors is investigated above the transition temperature. It is found that this effect is dominant for the positive magnetoresistance in a parallel magnetic field and the phase relaxation time ${\tau }_{\varphi }$ can be estimated by a comparison of this term with experimental data for single-crystal films. This value is consistent with an estimate from the orbital effect of the Maki-Thompson term in a perpendicular magnetic field, and a temperature dependence of ${\tau }_{\varphi }$ proportional to $\frac{1}{T}$ is obtained from the experimental data.