H-modulated microwave absorption and resistive transition in the high-Tc superconductor YBa2Cu3O7

Abstract

Abstract The derivative microwave absorption near T c in presence of a sufficiently high field ( H ⩾1 kOe) is related to the temperature variation of resistivity. This idea, originally proposed by Kim et al. (1988), is extended to take into account the effects of the anomalous resistive tail by using the thermoactivated flux-creep model proposed by Tinkham (1988). This gives a simple explanation for some relevant features observed in the temperature behaviour of the ESR absorption, as the asymmetry of the peak at T c , with the long tail extending toward low temperatures, and the field dependence of height and linewidth, for which the model provides H −1 and H 2/3 behaviour, respectively, ESR data on YBa 2 Cu 3 O 7 powder are in satisfactory agreement with this picture, when the role of the intrinsic 2D-character of this compound is properly taken into account. This allows us to deduce consistent values for the parameters a ‖ and a ⊥ of the anisotropic resistivity.