Anomalous scattering rate and microwave absorption in Bi₂Sr₂CaCu₂O₈₊δ and Y Ba₂Cu₃O₇₋δ

C. Kusko, Northeastern University
Z. Zhai, Northeastern University
R. S. Markiewicz, Northeastern University
S. Sridhar, Northeastern University

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Originally posted at http://arxiv.org/abs/cond-mat/0102288v1.

Abstract

We determine the scattering rate from microwave measurements for an optimally doped Bi-2212 single crystal, using a simple two fluid model with a d-wave symmetry order parameter. In the superconducting state, the calculated scattering rate is three orders of magnitude smaller than that determined from ARPES experiments. A similar anomalously large decrease in the scattering rate is also required to explain the data within a gap-quasiparticle scenario for other HTS, such as Y Ba₂Cu₃O₇₋δ. The results suggest that the assumption of normal excitations vanishing at low T is invalid and an additional charge mode is responsible for the microwave absorption.