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TT: Fachverband Tiefe Temperaturen

TT 79: Correlated Electrons - Poster Session

TT 79.4: Poster

Mittwoch, 2. April 2014, 15:00–19:00, P2

Evolution of ferromagnetic correlations in FeGa_3−xGe_x probed by ^69,71Ga nuclear quadrupolar resonance — •M. Majumder, M. Wagner-Reetz, P. Khuntia, Yu. Grin, and M. Baenitz — Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany

Binary Fe based semimetals like FeSi, FeSb₂ and FeGa₃ earned great attention because of their unconventional ground state (possible Kondo insulators) and good thermoelectric performance. Metallic behavior and Fe based magnetism can be introduced by various substitutions. In contrast to FeSb₂ (where Te substitution results in a disorder dominated Griffiths phase) [1], the system FeGa₃ seems to be an ideal candidate to study the evolution of ferromagnetic quantum criticality (FMQC) by magnetic resonance. Recently it was shown that Fe(Ga, Ge)₃ develops FMQC behavior without strong disorder effects [2,3]. The nuclear quadrupolar resonance (NQR) spectra provide direct information about the degree of local disorder (line width) and the critical fluctuations at the verge of FM ordering (spin lattice relaxation at zero field). In FeGa₃ four NQR lines have been found, of which two lines are from the two Ga sites in the crystal structure and other two are due to the two Ga isotopes [4]. ^69,71Ga NQR investigation have been performed in FeGa_3−xGe_x polycrystalline sample with x=0.1 (absent magnetic order), 0.2 (T_C ≃ 6 K) and x_c ≈ 0.15 (critical concentration for FMQC).
Phys. Rev. Lett. 109, 256401 (2012)
Phys. Rev.B 86, 144421, (2012)
arXiv: 1304.1897 (2013)
arXiv: 1311.1501 (2013)