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 τ_φ 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 τ_φ proportional to 1/T is obtained from the experimental data.