Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 45: Superconductivity: Fe-based Superconductors - 1111,111, FeSe
TT 45.3: Vortrag
Dienstag, 1. April 2014, 14:30–14:45, HSZ 201
Microscopic insight into the poisoning effect of Mn in LaFe1−xMnxAsO0.89F0.11 — •Franziska Hammerath1,2, Pietro Bonfá3, Samuele Sanna1, Giacomo Prando1,2, Roberto De Renzi3, Pietro Carretta1, Yoshiaki Kobayashi4, and Masatoshi Sato4 — 1Dipartimento di Fisica and Unitá CNISM di Pavia, I-27100 Pavia, Italy — 2Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Germany — 3Dipartimento di Fisica and Unitá CNISM di Parma, I-43124 Parma, Italy — 4Department of Physics, Division of Material Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
We investigate the extraordinary poisoning effect of Mn on superconductivity (SC) in
LaFe1−xMnxAsO0.89F0.11 [1] by means of muon spin rotation (µSR) and nuclear quadrupole resonance (NQR) on compounds with x=0.025 % up to x=0.75 %. We find that the iron plane electronic environment is extremely sensitive to the addition of Mn, even though charge doping effects can be neglected. Already 0.2 % Mn suppress SC completely, while static magnetism is observed for x = 0.1 % and becomes enhanced upon further Mn substitution. This re-entrant magnetism is found to be intrinsic to the FeAs plane. A progressive increase of low energy spin fluctuations, expressed in an enhanced NQR spin-lattice relaxation T1−1, is observed upon Mn substitution. The analysis of T1−1 for the sample closest to the the crossover between SC and magnetism points towards an antiferromagnetic quantum critical point at this crossover.
M. Sato et al., JPSJ 79, 014710 (2010).