Regensburg 2025 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 16: Superconductivity: Properties and Electronic Structure II
TT 16.2: Vortrag
Dienstag, 18. März 2025, 09:45–10:00, H32
Lattice dynamical studies in the unconventional superconductor: LiFeAs — •Akshay Tewari1, Sabine Wurmehl2, Bernd Büchner2, Andrea Piovano3, and Markus Braden1 — 1II.Physics Institute, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany — 2IFW Dresden, D-01171 Dresden, Germany — 3ILL, 71 avenue des Martyrs, 38000 Grenoble, France
LiFeAs crystallizes in a tetragonal structure(P4/nmm) and is superconducting below Tc=18K. Unlike other iron pnictides, LiFeAs does not exhibit long-range magnetic order, but has AFM fluctuations at incommensurate positions. Studies suggest that superconductivity in LiFeAs is driven by electronic correlations but a contribution from electron phonon coupling is still debated. We have studied the phonon dispersion of LiFeAs using inelastic neutron scattering on large single crystals to search for anomalies in the dispersion which are signatures of electron phonon coupling. We could determine almost all branches along main symmetry directions by analyzing the data with force-model lattice dynamical calculations. Temperature dependencies of specific phonon modes were also examined. Our experimental results provide significant differences to the DFT calculations previously reported[1,2]. No pronounced instability was observed but strong relative energy shifts of 6% were detected for specific modes in the temperature dependent scans. The overall dispersion fits the lattice dynamical model and is also supported by more recent DFT calculations.
[1] G.Q. Huang et al. PRB 82, 014511 (2010).
[2] R.A. Jishi et al., Adv. in Cond.Mat.Phys. 804343(2010).
Keywords: FeAs superconductors; Lattice dynamics; Inelastic neutron scattering; electron phonon coupling