Correlation between the Hall Resistance and Magnetoresistance in the Mixed State of an Nd2 − xCexCuO4 + δ Electronic Superconductor

Resumo

The Hall resistance and the magnetoresistance in the mixed state of the Nd_{2 − x}Ce_xCuO_{4 + δ} quasi-two-dimensional system near the antiferromagnetic-superconductor (AF-SC) phase transition have been measured at doping levels x = 0.14 and 0.15, and a correlation has been established. This correlation can be analyzed using the following power relationship: ρ_xy(B) ~ [ρ_xx (B)]^β. It was found that index β varied from 0.94 ± 0.03 in the region of AF and SC coexistence (x = 0.14) to 0.6 ± 0.1 in the SC region with the maximum critical temperature (x = 0.15) at low temperatures and weak magnetic fields. This reduction suggests that the symmetry of carrier pairing changes at the boundary of the transition from the phase of antiferromagnetic ordering and spin density waves to the superconducting phase in the presence of antiferromagnetic spin fluctuations.