Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 44: Correlated Electrons: Quantum-Critical Phenomena – Experiments
TT 44.7: Talk
Tuesday, March 17, 2015, 15:30–15:45, H 3005
Towards ferromagnetic quantum criticality in FeGa3−xGex: 71Ga NQR as a zero field microscopic probe — •Mayukh Majumder1, Maik Wagner-Reetz1, Raul Cardoso-Gil1, Peter Gille2, Yu Grin1, and Michael Baenitz1 — 1Max Plank Institute for Chemical Physics of Solids, Dresden, Germany — 2Ludwig-Maximilians-Universität Munchen, Germany
FeGa3 is an ideal candidate to study the evolution of a metallic state and probably approaching to a ferromagnetic (FM) critical point upon Ge substitution by the local nuclear quadrupolar resonance (NQR) probe [1, 2]. 71Ga NQR, magnetization and specific heat measurements have been performed in FeGa3−xGex polycrystalline sample with x = 0.05, 0.1 (absent magnetic order), x = 0.15 (critical) and 0.2 (TC ∼ 6 K). 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). For x = 0.15 we found 3D quantum critical itinerant FM fluctuations and x = 0.2 exhibits weakly FM Moriya like behavior. Low doped samples surprisingly show heavy fermion behavior at low temperature (γ = 70 mJ/mole-K2) with dominating antiferromagnetic correlations.
[1] Phys. Rev.B 86, 144421, (2012).
[2] arXiv: 1304.1897 (2013).
[3] Phys. Rev. B 89, 104426 (2014).