Microwave Absorption Peaks : Signatures of Spin Dynamics in Cuprates

S. Sridhar; Z. Zhai; A. Erb

paper

Microwave Absorption Peaks : Signatures of Spin Dynamics in Cuprates

arXiv:cond-mat/9906053

Abstract

We show that a common feature of temperature-dependent microwave absorption is the presence of absorption peaks. $a c$ loss peaks can arise when the internal $T$ -dependent magnetic relaxation time crosses the measurement frequency. These features are observed in the \QTR{em}{insulating} ( $S r_{x} C a_{14 - x} C u_{24} O_{41}$ , $L a_{5/3} S r_{1/3} N i O_{4}$ and $Y B a_{2} C u_{3} O_{6.0}$ ), \QTR{em}{pseudo-gap} ( $T > T_{c}$ in underdoped $Y B a_{2} C u_{3} O_{7 - I^´}$ , $H g : 1223$ and $H g : 1201$ ) and \QTR{em}{superconducting} ( $T < T_{c}$ ) states of the oxides. The commonality of these features suggests a magnetic (spin) mechanism, rather than a quasiparticle origin, for the so-called ``conductivity'' peaks observed in the cuprate superconductors.

7 pages, 2 ps format figures