Effect of magnetic field on the pseudogap phenomena in high-T-c cuprates

We theoretically investigate the effect of magnetic field on the pseudogap phenomena in High-T, cuprates. The obtained results well explain the experi mental results including their doping dependences. In our previous paper [J . Phys. Sec. Jpn. 68(1999) 2999]; we have shown that the pseudogap phenomen a observed in High-T, cuprates are naturally understood as a precursor of t he strong coupling superconductivity. On the other hand; there is an interp retation for the recent high field NMR measurements to be an evidence denyi ng the pairing scenarios for the pseudogap. In this paper, we investigate t he magnetic field dependence of NMR 1/T1T on the basis of our formalism and show the interpretation to be inappropriate. We consider the Landau quanti zation for the superconducting fluctuations as a main effect of the magneti c field. The results indicate that the value of the characteristic magnetic field (B-ch) is remarkably large in case of the strong coupling supercondu ctivity, especially near the pseudogap onset temperature (T*). Therefore, t he magnetic field dependences can not be observed and T* does not vary when the strong pseudogap anomaly is observed. On the other hand, B-ch is Small in the comparatively weak coupling case and T* varies when the weak pseudo gap phenomena are observed. These results properly explain the high magneti c field NMR experiments continuously from under-doped to over-doped cuprate s. Moreover, we discuss the transport phenomena in the pseudogap phase. The behaviors of the in-plane resistivity, the Hall coefficient and the c-axis resistivity in the pseudogap phase are naturally understood by considering the d(x2-y2)-wave pseudogap.