Microwave absorption study in the ferromagnetic superconductor Gd1.4Ce0.6RuSr2Cu2O10-delta

We have performed microwave absorption (MWA) and ferromagnetic resonance measurements (FMR) in Gd1.4Ce0.6RuSr2Cu2O10-delta polycrystalline samples between 300 and 8 K. Below the magnetic ordering temperature (T-m approximate to 89 K) a MWA is observed due to the appearance of weak ferromagnetism (WFMWA). The intensity of the WFMWA decreases as T approaches the superconducting (SC) state at T-c approximate to 45 K. For T less than or equal to T-c, a new and much stronger MWA (SCMWA) is found. This SCMWA may be associated to Josephson intergrain and to viscose dynamic dissipation of intragrain Abrikosov vortex in the SC state.