caa a22 4500 445380179 CHVBK 20180317143015.0 cr unu---uuuuu 170323e20111001xx s 000 0 eng 10.1007/s10948-011-1177-6 doi (NATIONALLICENCE)springer-10.1007/s10948-011-1177-6 The Structural Distortion in Antiferromagnetic LaFeAsO Investigated by a Group-Theoretical Approach [Elektronische Daten] [Ekkehard Krüger, Horst Strunk] As experimentally well established, undoped LaFeAsO is antiferromagnetic below 137K with the magnetic moments lying on the Fe sites. We determine the orthorhombic body-centered group Imma (74) as the space group of the experimentally observed magnetic structure in the undistorted lattice, i.e., in a lattice possessing no structural distortions in addition to the magnetostriction. We show that LaFeAsO possesses a partly filled "magnetic band” with Bloch functions that can be unitarily transformed into optimally localized Wannier functions adapted to the space group Imma. This finding is interpreted in the framework of a nonadiabatic extension of the Heisenberg model of magnetism, the nonadiabatic Heisenberg model. Within this model, however, the magnetic structure with the space group Imma is not stable but can be stabilized by a (slight) distortion of the crystal turning the space group Imma into the space group Pnn2 (34). This group-theoretical result is in accordance with the experimentally observed displacements of the Fe and O atoms in LaFeAsO as reported by Clarina de la Cruz et al. (Nature 453:899, 2008). Springer Science+Business Media, LLC, 2011 Magnetism nationallicence Nonadiabatic Heisenberg model nationallicence Group theory nationallicence Krüger Ekkehard Institut für Materialwissenschaft, Materialphysik, Universität Stuttgart, 70569, Stuttgart, Germany aut Strunk Horst Institut für Materialwissenschaft, Materialphysik, Universität Stuttgart, 70569, Stuttgart, Germany aut Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/7(2011-10-01), 2103-2117 1557-1939 24:7<2103 2011 24 10948 https://doi.org/10.1007/s10948-011-1177-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10948-011-1177-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Krüger Ekkehard Institut für Materialwissenschaft, Materialphysik, Universität Stuttgart, 70569, Stuttgart, Germany aut NATIONALLICENCE 700 1- Strunk Horst Institut für Materialwissenschaft, Materialphysik, Universität Stuttgart, 70569, Stuttgart, Germany aut NATIONALLICENCE 773 0- Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/7(2011-10-01), 2103-2117 1557-1939 24:7<2103 2011 24 10948 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer