Measurements of the Fe K-edge X-ray absorption near edge (XANES) spectra of LnOFeAs high T-c superconductors exhibit small but measurable changes across the tetragonal to orthorhombic phase structural phase transition. Calculations, based on the local structure centered at the Fe site obtained by crystallographic investigations, reproduce the observed changes in the spectra under the change of the crystal structure, indicating variations in the Fe local unoccupied electronic states. Calculated Fe density of states including stripe spin ordering in the orthorhombic phase show significant modifications with respect to Fe 3d density of states in the tetragonal phase or the density of states in the orthorhombic phase calculated ignoring spin ordering. This implies that the striped spin ordering in the orthorhombic phase is necessary to describe its electronic properties not only in the ground state but also for excited states above the Fermi energy. (C) 2010 Elsevier Ltd. All rights reserved.
Antiferromagnetic stripe ordering at the tetragonal-orthorhombic transition in LnOFeAs probed by X-ray absorption spectroscopy / J. M., De Leon; J., Lezama Pacheco; Bianconi, Antonio; Saini, Naurang Lal. - In: JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS. - ISSN 0022-3697. - 71:8(2010), pp. 1118-1122. (Intervento presentato al convegno 5th International Conference on Study of Matter at Extreme Conditions tenutosi a Miami, FL nel MAR 28-APR 02, 2009) [10.1016/j.jpcs.2010.03.017].
Antiferromagnetic stripe ordering at the tetragonal-orthorhombic transition in LnOFeAs probed by X-ray absorption spectroscopy
BIANCONI, Antonio;SAINI, Naurang Lal
2010
Abstract
Measurements of the Fe K-edge X-ray absorption near edge (XANES) spectra of LnOFeAs high T-c superconductors exhibit small but measurable changes across the tetragonal to orthorhombic phase structural phase transition. Calculations, based on the local structure centered at the Fe site obtained by crystallographic investigations, reproduce the observed changes in the spectra under the change of the crystal structure, indicating variations in the Fe local unoccupied electronic states. Calculated Fe density of states including stripe spin ordering in the orthorhombic phase show significant modifications with respect to Fe 3d density of states in the tetragonal phase or the density of states in the orthorhombic phase calculated ignoring spin ordering. This implies that the striped spin ordering in the orthorhombic phase is necessary to describe its electronic properties not only in the ground state but also for excited states above the Fermi energy. (C) 2010 Elsevier Ltd. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
