THERMAL, MAGNETIC, AND TRANSPORT-PROPERTIES OF SINGLE-CRYSTAL SR1-XCAXRUO3 LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1.0)

SrRuO3 is a highly correlated, narrow d-band metal which undergoes a f erromagnetic transition at T-c = 165 K. CaRuO3, which is also a highly correlated metal, has the same crystal structure, comparable electric al resistivity and similar effective Ru moment, but it remains paramag netic at least down to 1 K. High- and low-field magnetization and susc eptibility, thermoremanent magnetization, low-temperature heat capacit y, electrical resistivity, and Hall effect measurements are presented on as-grown, untwinned, orthorhombic single-crystal samples of Sr1-xCa xRuO3 for the entire concentration range 0 less than or equal to x les s 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 clo se to 1.0. The critical Sr doping of paramagnetic CaRuO, required to c ause magnetic correlations among the Ru moments is congruent to 1 at.% . Magnetization to 7 T shows strong hysteresis for mixed (x>0) crystal s 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 d ata for x=1.0 show it to be a highly exchange enhanced paramagnet, a b orderline antiferromagnet or ferromagnet.:This is consistent with prev ious' Ru-O in-plane and out-of-plane doping studies. Low-temperature h eat capacity (1<T<20K) shows that the mass enhancement (gamma = 29 mJ/ mol K-2 and mapproximate to 3 for x=0) and the Debye temperature (The ta(D)=390 K for x=0) are nonmonotonically varying with increasing x. T he large electrical resistivity suggests these materials are ''bad'' m etals, with a mean free path at room temperature approximate to 10 A f or x=0. The Hall effect shows a sign reversal for x=0 and x=1.0, but n ot for mixed crystals. The data are compared where it is appropriate t o data derived from comparable experiments from polycrystalline sample s and from epitaxially grown thin films. The results support the highl y electron-correlated nature of ordered magnetism in Ru-based oxides a nd the results should help to advance our understanding of the transpo rt, magnetic, and thermodynamic properties of bad metals.