Towards ferromagnetic quantum criticality in FeGa3-xGex: 71Ga NQR as a zero field microscopic probe

Abstract

71Ga NQR, magnetization and specific heat measurements have been performed on polycrystalline Ge doped FeGa3 samples. A crossover from an insulator to a correlated local moment metal in the low doping regime and the evolution of itinerant ferromagnet upon further doping is found. For the nearly critical concentration at the threshold of ferromagnetic order, xC=0.15, (1/T1T) exhibits a pronounced T4/3 power law over two orders of magnitude in temperature which indicates 3D quantum critical ferromagnetic fluctuations. Furthermore, for the ordered x = 0.2 sample (TC = 6 K) 1/T1T could be fitted well in the frame of Moriya's SCR theory for weakly FM systems with 1/T1T proportional to chi. In contrast to this, the low doping regime nicely displays local moment behavior where 1/T1T proportional to chi2 is valid. For temperature tending to zero the Sommerfeld ratio = (C/T) is enhanced (70 mJ/mole-K2 for x = 0.1) which indicates the formation of heavy 3d-electrons.

5 pages, 4 figures

References in corpus (6)

• Quantum Criticality in Heavy Fermion Metals
• Heavy Fermions and Quantum Phase Transitions
• Multiple energy scales at a quantum critical point
• Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment
• Phonon-drag effect in FeGa3
• Electronic Griffiths Phase in the Te - Doped Semiconductor FeSb${}_2$

Cited by in corpus (5)

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• Spin dynamics of FeGa${}_{3-x}$Ge${}_x$ studied by Electron Spin Resonance
• Competing magnetic correlations across the ferromagnetic quantum critical point in the Kondo system CeTi${}_{1-x}$V${}_x$Ge${}_3$: ${}^{51}$V NMR as a local probe
• 121,123Sb NQR as a microscopic probe in Te doped correlated semimetal FeSb2 : emergence of electronic Griffith phase, magnetism and metallic behavior %