Details

Autor(en) / Beteiligte

• NAKAMURA, J
• KARPPINEN, M
• KAREN, P
• LINDEN, J
• YAMAUCHI, H

Titel

Isovalent-substitution effect on the Verwey-type transition in the A-site-ordered double perovskite (Ba, Sr)RFe2O5

Ist Teil von

• Physical review. B, Condensed matter and materials physics, 2004-10, Vol.70 (14), p.144104.1-144104.6

Ort / Verlag

Ridge, NY: American Physical Society

Erscheinungsjahr

2004

Link zum Volltext

Quelle

PROLA

Beschreibungen/Notizen

• Two types of chemical-pressure effects on the Verwey-type transition in Ba Sm Fe 2 O 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 TV 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 1 − x Sr x ) Sm Fe 2 O 5 . Of various structural parameters determined by synchrotron x-ray diffraction above TV, the magnitude of the orthorhombic distortion (=b− a ) is found to correlate with TV in a manner that unifies both substitution schemes. It is suggested that when an increase in b− a above TV is achieved by means of the structural substitution, it makes it easier for the dxz Fe 2 + orbital ordering to occur below TV. © 2004 American Physical Society