Isovalent-substitution effect on the Verwey-type transition in the A-site-ordered double perovskite (Ba,Sr)RFe{sub 2}O{sub 5}
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan)
- Department of Chemistry, University of Oslo, N-0315 Oslo (Norway)
- Department of Physics, Aabo Akademi, FIN-20500 Turku (Finland)
Two types of chemical-pressure effects on the Verwey-type transition in BaSmFe{sub 2}O{sub 5} are studied, viz., ionic-size contractions at the Ba and Sm sites. Whereas the replacement of Sm by the smaller Eu and Gd atoms increases the transition temperature T{sub V} from 232 K to 264 K, the Sr-for-Ba substitution decreases it from 232 K to 180 K for x=0.15 in (Ba{sub 1-x}Sr{sub x})SmFe{sub 2}O{sub 5}. Of various structural parameters determined by synchrotron x-ray diffraction above T{sub V}, the magnitude of the orthorhombic distortion (=b-a) is found to correlate with T{sub V} in a manner that unifies both substitution schemes. It is suggested that when an increase in b-a above T{sub V} is achieved by means of the structural substitution, it makes it easier for the d{sub xz} Fe{sup 2+} orbital ordering to occur below T{sub V}.
- OSTI ID:
- 20664910
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 70, Issue 14; Other Information: DOI: 10.1103/PhysRevB.70.144104; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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