Antiferromagnetic Alignment and Relaxation Rate of Gd Spins in the High Temperature Superconductor GdBa_2Cu_3O_(7-delta)

Abstract

The complex surface impedance of a number of GdBa${}_2$Cu${}_3$O${}_{7-\delta }$ single crystals has been measured at 10, 15 and 21 GHz using a cavity perturbation technique. At low temperatures a marked increase in the effective penetration depth and surface resistance is observed associated with the paramagnetic and antiferromagnetic alignment of the Gd spins. The effective penetration depth has a sharp change in slope at the Néel temperature, $T_N$, and the surface resistance peaks at a frequency dependent temperature below 3K. The observed temperature and frequency dependence can be described by a model which assumes a negligibly small interaction between the Gd spins and the electrons in the superconducting state, with a frequency dependent magnetic susceptibility and a Gd spin relaxation time ${\tau }_s$ being a strong function of temperature. Above $T_N$, ${\tau }_s$ has a component varying as $1/(T-T_N)$, while below $T_N$ it increases $\sim T^{-5}$.

4 Pages, 4 Figures. Submitted to Phys. Rev. B

References in corpus (1)

• New features in the microwave response of YBCO crystals: Evidence for a multi-component order parameter

Cited by in corpus (1)

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