Thermoelectromotive force in Bi_2Sr_2Ca_2Cu_4O_(11) bismuth-based high-temperature superconductor

摘要

The temperature dependence of the thermoemf in Bi_2Sr_2Ca_2Cu_4O_(11) bismuth-based high-temperature superconductors is studied. The thermoemf is positive at high temperatures (T 300 K) and negative at low temperatures. As the temperature decreases, the thermoemf reaches a maximum slightly above T_c and then sharply drops to zero. The results can be explained in the framework of the two-band theory with a linear temperature term.