title: Antiferromagnetic-paramagnetic insulating transition in Cr-doped V(2)O(3) investigated by EXAFS analysis.
abstract: We have performed extended x-ray absorption fine-structure (EXAFS) spectroscopy on a 2.8% Cr-doped V(2)O(3) sample, with the aim of studying its structural evolution in a wide temperature range across the paramagnetic-antiferromagnetic insulating phase transition at T(c). The data were registered with two different set-ups in fluorescence and transmission geometries, for polarized and unpolarized spectra, respectively. Our idea, based on previous experiments reported in the literature, is that extended structural modifications of the nominal trigonal symmetry are present in the paramagnetic insulating phase for several tens of degrees above T(c), involving further-nearest-neighbor vanadium ions. Our data confirm that the paramagnetic insulating phase is not structurally homogeneous in a temperature range of about 30 K around T(c), where local distortions of monoclinic symmetry involving further-nearest neighbors are present. Moreover, the analysis of the absorption profile at Cr K-edge suggests that Cr ions enter the lattice randomly. We finally analyze our findings in light of current theoretical models.
authors.affiliation: Dipartimento di Fisica 'E Amaldi', Università di Roma TRE, via della Vasca Navale 84, I-00146 Roma, Italy. TASC-CNR c/o OGG-GILDA ESRF, Polygone Scientifique Louis Néel, 6 rue Jules Horowitz, F-38000 Grenoble, France.
authors.forename: C
authors.initials: C
authors.lastname: Meneghini
authors.forename: S
authors.initials: S
authors.lastname: Di Matteo
authors.forename: C
authors.initials: C
authors.lastname: Monesi
authors.forename: T
authors.initials: T
authors.lastname: Neisius
authors.forename: L
authors.initials: L
authors.lastname: Paolasini
authors.forename: S
authors.initials: S
authors.lastname: Mobilio
authors.forename: C R
authors.initials: CR
authors.lastname: Natoli
authors.forename: P A
authors.initials: PA
authors.lastname: Metcalf
authors.forename: J M
authors.initials: JM
authors.lastname: Honig