Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 43: Superconductivity: Fe-based Superconductors – 122
TT 43.2: Vortrag
Dienstag, 17. März 2015, 14:30–14:45, H 2053
Probing the density of states in EuFe2−xRuxAs2 — •Mamoun Hemmida1, Hans-Albrecht Krug von Nidda1, Axel Günther1, Alois Loidl1, Andreas Leithe-Jasper2, Walter Schnelle2, Helge Rosner2, and Jörg Sichelschmidt2 — 1Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute for Physics, University of Augsburg, 86135 Augsburg, Germany — 2Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
Electron spin resonance of Eu2+ (4f7, S = 7/2) in europium-based iron pnictides successfully probes the local density of states of the conduction electrons [1]. Starting from the mother compound EuFe2As2, the usual metallic phase is characterized by the linear increase of the linewidth on increasing temperature (Korringa slope b = 8 Oe K−1) due to the Korringa relaxation via the conduction electrons, while this Relaxation contribution is switched off in the spin-density wave phase (T < TSDW), where the linewidth is mainly determined by the crystal-electric field of the ligands [2]. Thus, we observe the same phenomenology like in insulators, despite of the high conductivity. Substitution of ruthenium for iron gradually suppresses the SDW phase up to x = 0.5 and reduces the Korringa slope down to about b = 0.3 Oe K−1 for x = 2. This indicates a continuously decreasing conduction-electron density of states at the Fermi energy on increasing Ru Substitution in a good agreement with band-structure calculations.
[1] M. Hemmida et al., Phys. Rev. B 90, 205105 (2014).
[2] E. Dengler et al., Phys. Rev. B 81, 024406 (2010).