Coexistence of ferromagnetism and superconductivity in the hybrid ruthenate-cuprate compound RuSr_2GdCu_2O_8 studied by muon spin rotation (\mu SR) and DC-magnetization

摘要

We have investigated the magnetic and the superconducting properties of thehybrid ruthenate-cuprate compound RuSr_{2}GdCu_{2}O_{8} by means of zero-fieldmuon spin rotation- (ZF-$\mu $SR) and DC magnetization measurements. TheDC-magnetisation data establish that this material exhibits ferromagnetic orderof the Ru-moments ($\mu (Ru) \approx 1 \mu_{B}$) below T_{Curie} = 133 K andbecomes superconducting at a much lower temperature T_c = 16 K. The ZF-$\mu $SRexperiments indicate that the ferromagnetic phase is homogeneous on amicroscopic scale and accounts for most of the sample volume. They also suggestthat the magnetic order is not significantly modified at the onset ofsuperconductivity.