Europhys. Lett., 57 (2) , p. 267 (2002)
Two mechanisms of pseudogap formation in Bi-2201: Evidence from the c-axis magnetoresistanceA. N. Lavrov, Y. Ando and S. Ono
Central Research Institute of Electric Power Industry 2-11-1 Iwato-kita, Komae, Tokyo 201-8511, Japan
(Received 14 June 2001; accepted in final form 26 October 2001)
Measurements of the c-axis resistivity and magnetoresistance have been used to investigate the pseudogap (PG) behavior in Bi 2+zSr 2-x-zLa xCuO y (Bi-2201) crystals at various hole densities. While the PG opening temperature T* increases with decreasing hole doping, the magnetic-field sensitivity of the PG is found to have a very different trend: it appears at lower temperatures in more underdoped samples and vanishes in non-superconducting samples. These data suggest that besides the field-insensitive pseudogap emerging at T*, a distinct one is formed above as a precursor to superconductivity.
74.25.Fy - Transport properties (electronic and thermal conductivity).
74.20.Mn - Non-conventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.).
74.72.Hs - Bi-based cuprates.
© EDP Sciences 2002