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TT: Fachverband Tiefe Temperaturen

TT 5: Superconductivity: Fe-based Superconductors - FeSe and 122

TT 5.10: Vortrag

Montag, 1. April 2019, 12:00–12:15, H23

Interplay of lattice, electronic, and spin degrees of freedom in detwinned BaFe₂As₂: A Raman scattering study — •Andreas Baum^1,2, Ying Li³, Milan Tomić³, Nenad Lazarević⁴, Daniel Jost^1,2, Florian Löffler^1,2, Bernhard Muschler¹, Thomas Böhm^1,2, Jiun-Haw Chu^5,6,7, Ian R. Fisher^5,6, Roser Valentí³, Igor I. Mazin⁸, 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, 60438 Frankfurt am Main, Germany — ⁴Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, 11080 Belgrade, Serbia — ⁵SIMES, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA — ⁶GLAM and Department of Applied Physics, Stanford University, Stanford, CA 94305, USA — ⁷Department of Physics, University of Washington, Seattle WA 98195, USA — ⁸Code 6393, Naval Research Laboratory, Washington, DC 20375, 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 3.1 eV with distinct differences between the antiferromagnetically and the ferromagnetically ordered direction. The E_g phonon at 130 cm⁻¹ splits into two modes having B_2g and B_3g symmetry which differ by 10 cm⁻¹. Both effects can be attributed to the emergence of magnetic order, rather than the structural transition, by DFT calculations.