Polycrystalline samples of RuSr2GdCu2O8 with a magnetic ordering temperatur
e (T-M = 135 K) and a resistively determined superconducting onset temperat
ure (T-c = 45 K) were synthesized using a solid-state reaction. Transport a
nd magnetic measurements indicated coexistence of weak ferromagnetic-like o
rder and superconductivity at low temperatures. A novel radio-frequency (rf
) resonant technique was employed to probe the mixed state response. The re
sults clearly indicate that in the superconducting state (T < T-c), the rf
response is dominated by the flux lattice dynamics and in the normal state
(T-c < T < T-M), the data are consistent with transverse susceptibility exh
ibiting sharp peaks at characteristic switching and anisotropy fields. (C)
2001 American Institute of Physics.