title: Retention of the tetragonal to orthorhombic structural transition in F-substituted SmFeAsO: a new phase diagram for SmFeAs(O(1-x)F(x)).
abstract: In this Letter we propose a new phase diagram for the SmFeAs(O(1-x)F(x)) system, based on careful analysis of synchrotron powder diffraction data, SQUID, and muon spin rotation measurements. The tetragonal to orthorhombic structural transition is slightly affected by F content and is retained for the superconducting samples, even at optimal doping. These findings relate the AFM transition on a different ground with respect to the structural one and suggests that orbital ordering could be the driving force for symmetry breaking.
authors.affiliation: SPIN-CNR, corso Perrone 24, 16152 Genova, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Martinelli
authors.forename: A
authors.initials: A
authors.lastname: Palenzona
authors.forename: M
authors.initials: M
authors.lastname: Tropeano
authors.forename: M
authors.initials: M
authors.lastname: Putti
authors.forename: C
authors.initials: C
authors.lastname: Ferdeghini
authors.forename: G
authors.initials: G
authors.lastname: Profeta
authors.forename: E
authors.initials: E
authors.lastname: Emerich