Thermal, magnetic, and transport properties of single-crystal Sr1-xCaxRuO3 (0<=x<=1.0)

SrRuO3 is a highly correlated, narrow d-band metal which undergoes a ferromagnetic transition at T-c = 165 K. CaRuO3, which is also a highly correlated metal, has the same crystal structure, comparable electrical resistivity and similar effective Ru moment, but it remains paramagnetic at least down to 1 K. High- and low-field magnetization and susceptibility, thermoremanent magnetization, low-temperature heat capacity, electrical resistivity, and Hall effect measurements are presented on as-grown, untwinned, orthorhombic single-crystal samples of Sr1-xCaxRuO3 for the entire concentration range 0 less than or equal to x less than or equal to 1.0. T-c is depressed uniformly with increasing x, all the way to x=1.0, with possible spin-glass-type ordering for x close to 1.0. The critical Sr doping of paramagnetic CaRuO, required to cause magnetic correlations among the Ru moments is congruent to 1 at.%. Magnetization to 7 T shows strong hysteresis for mixed (x>0) crystals only, with evidence for a rotation of the easy magnetic axis out of the ab plane. Low-temperature magnetization in de fields to 30 T for x=0 shows a lack of saturation to the full S=1 moment, 2 mu(B)/Ru atom, underscoring the itinerant character of the ferromagnetism. Similar data for x=1.0 show it to be a highly exchange enhanced paramagnet, a borderline antiferromagnet or ferromagnet.:This is consistent with previous' Ru-O in-plane and out-of-plane doping studies. Low-temperature heat capacity (1<T<20K) shows that the mass enhancement (gamma = 29 mJ/mol K-2 and m*approximate to 3 for x=0) and the Debye temperature (Theta(D)=390 K for x=0) are nonmonotonically varying with increasing x. The large electrical resistivity suggests these materials are ''bad'' metals, with a mean free path at room temperature approximate to 10 A for x=0. The Hall effect shows a sign reversal for x=0 and x=1.0, but not for mixed crystals. The data are compared where it is appropriate to data derived from comparable experiments from polycrystalline samples and from epitaxially grown thin films. The results support the highly electron-correlated nature of ordered magnetism in Ru-based oxides and the results should help to advance our understanding of the transport, magnetic, and thermodynamic properties of bad metals.