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TT: Fachverband Tiefe Temperaturen

TT 79: Superconductivity: Fe-based Superconductors - 122

TT 79.2: Talk

Thursday, March 10, 2016, 15:45–16:00, H21

A light scattering study of detwinned BaFe₂As₂ — •Andreas Baum^1,2, Milan Tomić³, Daniel Jost^1,2, Ali Özkü^1,2, Bernhard Muschler¹, Florian Kretzschmar^1,2, Thomas Böhm^1,2, Nitin Chelwani^1,2, Jiun-Haw Chu^4,5, Ian R. Fisher^4,5, Roser Valentí³, and Rudi Hackl¹ — ¹Walther-Meissner-Institut, 85748 Garching, Germany — ²Fakultät für Physik E23, Technische Universität München, 85748 Garching, Germany — ³Institut für Theoretische Physik, Goethe-Universität Frankfurt — ⁴SIMES, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA — ⁵GLAM and Department of Applied Physics, Stanford, University, Stanford, CA 94305, USA

The magneto-structural phase transition of BaFe₂As₂ is studied by Raman spectroscopy with a focus on lattice dynamics. Using uniaxial pressure to detwin the sample allows us to resolve anisotropic features. The As A_1g phonon shows a resonance at high energies with distinct differences between the antiferromagnetically and the ferromagnetically ordered direction. The splitting of the E_g phonon at 130   cm⁻¹ into two modes having B_2g and B_3g symmetry can be attributed to the transition into the magnetically ordered state rather than the structural transition. Both effects can be attributed to the emergence of magnetic order by DFT calculations.