Thermal, magnetic, and transport properties of single-crystal Sr{sub 1{minus}x}Ca{sub x}RuO{sub 3} (0{le}x{le}1.0)
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States)
- Physics Department, Tufts University, Medford, Massachusetts 02155 (United States)
SrRuO{sub 3} is a highly correlated, narrow d-band metal which undergoes a ferromagnetic transition at T{sub c}=165K. CaRuO{sub 3}, 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 Sr{sub 1{minus}x}Ca{sub x}RuO{sub 3} for the entire concentration range 0{le}x{le}1.0. T{sub 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{sub 3} required to cause magnetic correlations among the Ru moments is {congruent}1at.{percent}. Magnetization to 7 T shows strong hysteresis for mixed (x{gt}0) crystals only, with evidence for a rotation of the easy magnetic axis out of the ab plane. Low-temperature magnetization in dc fields to 30 T for x=0 shows a lack of saturation to the full S=1 moment, 2{mu}{sub B}/Ruatom, 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{lt}T{lt}20K) shows that the mass enhancement ({gamma}=29mJ/molK{sup 2} and m{sup {asterisk}}{approx}3 for x=0) and the Debye temperature ({Theta}{sub D}=390K for x=0) are nonmonotonically varying with increasing x. The large electrical resistivity suggests these materials are {open_quotes}bad{close_quotes} metals, with a mean free path at room temperature {approx}10A for x=0. The Hall effect shows a sign reversal for x=0 and x=1.0, but not for mixed crystals. (Abstract Truncated)
- OSTI ID:
- 549302
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 56, Issue 1; Other Information: PBD: Jul 1997
- Country of Publication:
- United States
- Language:
- English
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