title: Lattice effects on ferromagnetism in perovskite ruthenates.
abstract: Ferromagnetism and its evolution in the orthorhombic perovskite system Sr(1-x)Ca(x)RuO3 have been widely believed to correlate with structural distortion. The recent development of high-pressure synthesis of the Ba-substituted Sr(1-y)Ba(y)RuO3 makes it possible to study ferromagnetism over a broader phase diagram, which includes the orthorhombic Imma and the cubic phases. However, the chemical substitutions introduce the A-site disorder effect on Tc, which complicates determination of the relationship between ferromagnetism and structural distortion. By clarifying the site disorder effect on Tc in several unique series of ruthenates in which the average bond length <A-O> remains the same but the bond-length variance varies, we are able to demonstrate a parabolic curve of Tc versus mean bond length <A-O>. A much higher Tc ∼ 177 K than that found in orthorhombic SrRuO3 can be obtained from the curve at a bond length <A-O>, which makes the geometric factor t = <A-O>/(√2<Ru-O>) ∼ 1. This result reveals not only that the ferromagnetism in the ruthenates is extremely sensitive to the lattice strain, but also that it has an important implication for exploring the structure-property relationship in a broad range of oxides with perovskite or a perovskite-related structure.
authors.affiliation: Department of Mechanical Engineering, The Materials Science and Engineering Program, The University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: J-G
authors.initials: JG
authors.lastname: Cheng
authors.forename: J-S
authors.initials: JS
authors.lastname: Zhou
authors.forename: John B
authors.initials: JB
authors.lastname: Goodenough
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D060328:Magnetic Phenomena; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D011312:Pressure; D017975:Ruthenium Compounds / Q000737:chemistry*; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D017975:Ruthenium Compounds; C059910:perovskite; D014025:Titanium
references.citation: Phys Rev B Condens Matter. 1996 Dec 1;54(22):R15622-R15625
references.pmid: 9985717
references.citation: Phys Rev Lett. 2005 Feb 18;94(6):065501
references.pmid: 15783742
references.citation: Phys Rev Lett. 2002 May 13;88(19):197203
references.pmid: 12005662
references.citation: Phys Rev Lett. 2008 Aug 15;101(7):077206
references.pmid: 18764577
references.citation: Phys Rev B Condens Matter. 1994 Aug 1;50(6):4260-4263
references.pmid: 9976724
references.citation: Proc Natl Acad Sci U S A. 2008 May 20;105(20):7115-9
references.pmid: 18480262