Electrical and thermal transport properties in high T-c superconductors: effects of a magnetic field

Experimental studies of the electric and heat currents in the normal, super conducting and mixed states of high T-c superconductors (HTcS) lead to char acterization, complementary to data obtained from equilibrium property base d techniques. A magnetic field superimposed on the superconducting sample g enerates magneto-transport phenomena, from which an excess electrical resis tivity, an excess thermoelectric power, the Hall or the Nernst effect. Diff erent behavioural effects allow one to distinguish various dissipation mech anisms, like quasi-particle scattering, vortex motion dissipation and super conductivity fluctuations, in particular when the Corbino geometry is used. Moreover bulk measurements of the thermal conductivity and the electrother mal conductivity in a magnetic field give us sure indications of the order parameter symmetry. The location of the mixed state phase transition lines in the technological phase diagram of HTcS are briefly pointed out through precise measurements performed over broad temperature and magnetic field ra nges. The results are mainly reviewed with the aim of defining further inve stigation lines. (C) 2001 Elsevier Science B.V. All rights reserved.