Dresden 2009 – scientific programme
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MA: Fachverband Magnetismus
MA 18: Spin Structures and Magnetic Phase Transitions
MA 18.5: Talk
Wednesday, March 25, 2009, 11:15–11:30, HSZ 401
Magnetic properties of LaO1−xFxFeAs — •Sangeeta Sharma1,2, John Kay Dewhurst1,2, Sam Shallcross3, Christophe Bersier1,2, Francesco Cricchio4, Antonio Sanna2,5, Sandro Massidda5, E. K. U Gross2, and Lars Nordstroem4 — 1Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany — 2Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany — 3Lehrstuhl für Theoretische Festkörperphysik, Staudstr. 7-B2, 91058 Erlangen, Germany. — 4Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala, Sweden. — 5Dipartimento di Fisica, Universita’ di Cagliari, Cittadella Universitaria, I-09042 Monserrato(CA), Italy
Using state-of-the-art first-principles calculations we have elucidated the complex magnetic and structural dependence of LaOFeAs upon doping. Our key findings are that (i) doping results in an orthorhombic ground state and (ii) there is a commensurate to incommensurate transition in the magnetic structure between x=0.025 and x=0.04. Our calculations further imply that in this system magnetic order persists up to the onset of superconductivity at the critical doping of x=0.05. Finally, our investigations of the undoped parent compound reveal a small itinerant moment and orthorhombic structure with both moment and distortion angle in excellent agreement with experiments.