Hall angle in YBa2Cu3O7- delta epitaxial films: Comparison between oxygen reduction and Pr doping.

Abstract

We have investigated the temperature dependence of the Hall angle in oxygen-deficient and Pr-doped ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ epitaxial films. The cotangent of the Hall angle follows a universal ${\mathit{T}}^{2}$ dependence in all superconducting samples, i.e., cot${\mathrm{\ensuremath{\theta}}}_{\mathit{H}}$=\ensuremath{\alpha}${\mathit{T}}^{2}$+C. In the ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ system the slope \ensuremath{\alpha} increases monotonically with \ensuremath{\delta} while the quantity C remains almost constant. Most important, there exists a linear correlation between ${\mathit{T}}_{\mathit{c}}$ and \ensuremath{\alpha}. In the ${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ series both \ensuremath{\alpha} and C increase with x. Combined with previous studies we conclude that the changes of \ensuremath{\alpha} and C are related to two distinct mechanisms for suppressing superconductivity. While the increase of C corresponds to a reduction of mobility, the change of \ensuremath{\alpha} reflects the variation in true carrier density.