Vanishingly small Maki-Thompson superconducting fluctuation in the magnetoresistance of high superconductors

The magnetoresistance (MR) of high-(Formula presented) cuprate superconductors (HTSCșs) is studied. We have shown that the Zeeman term of the Maki-Thompson (MT) process could not be detected in the longitudinal MR of 90 K YBCO crystals. We show here that the MT process is thought to be also negligible in the transverse MR of 90 K and Zn-doped YBCO crystals. The MR, which has been assigned previously to a MT-orbital process, is more naturally understood as normal-state orbital MR that is proportional to the square of the Hall angle. We conclude that the MT-fluctuation is vanishingly small, at least above (Formula presented), in these HTSCșs. In addition to the Hall measurements, MR measurements also support the hypothesis of two distinct relaxation times in HTSCșs.