  A hydrostatic pressure study was made on pure and Rh-doped specimens of the
superconducting ferromagnetic compounds Ru1-xRhxSr2GdCu2O8 (x = 0-0.15) by
means of measurement of electrical resistivity vs temperature, in pressures up
to 2 GPa. Partial substitution of Rh for Ru decreases the magnetization of the
material, lowers both the magnetic ordering temperature Tm, and the
superconducting transition temperature Tc, and promotes granularity. The effect
of pressure for all compositions is an increase in both the intra- and
intergranular superconductivity transition temperatures, Tc and Tp
respectively, as well as Tm. The rate of change of each transition temperature
with pressure first drops for Rh concentrations near 5%, increasing latter for
higher concentrations. While the rate of increase of Tc with pressure for all
compositions is 2-3 times lower than in YBCO materials, the simultaneous
increase of Tc and Tm with pressure could support the notion of competition
between superconductivity and ferromagnetism in these materials. The effect of
pressure on the weak-links was a significant improvement of inter-granular
connectivity.
