Microwave Electrodynamics of the Antiferromagnetic Superconductor GdBa_2Cu_3O_{7-\delta}

TL;DR

This study investigates the microwave electrodynamics of GdBa_2Cu_3O_{7-}, revealing how antiferromagnetic order influences superconducting properties through surface impedance measurements at low temperatures.

Contribution

It provides new insights into the interplay between antiferromagnetism and superconductivity in GdBa_2Cu_3O_{7-} using microwave surface impedance analysis.

Findings

Unusual upturn in surface resistance and reactance at low temperatures.

Strong peak in resistance around the Neel temperature T_N.

Magnetic permeability changes significantly near T_N.

Abstract

The temperature dependence of the microwave surface impedance and conductivity are used to study the pairing symmetry and properties of cuprate superconductors. However, the superconducting properties can be hidden by the effects of paramagnetism and antiferromagnetic long-range order in the cuprates. To address this issue we have investigated the microwave electrodynamics of GdBa_2Cu_3O_{7-\delta}, a rare-earth cuprate superconductor which shows long-range ordered antiferromagnetism below T_N=2.2 K, the Neel temperature of the Gd ion subsystem. We measured the temperature dependence of the surface resistance and surface reactance of c-axis oriented epitaxial thin films at 10.4, 14.7 and 17.9 GHz with the parallel plate resonator technique down to 1.4 K. Both the resistance and the reactance data show an unusual upturn at low temperature and the resistance presents a strong peak around T_N mainly due to change in magnetic permeability.