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Towards ferromagnetic quantum criticality inFeGa3−xGex:Ga71NQR as a zero-field microscopic probe
- Source :
- Physical Review B. 93
- Publication Year :
- 2016
- Publisher :
- American Physical Society (APS), 2016.
-
Abstract
- $^{71}\mathrm{Ga}$ NQR, magnetization, and specific-heat measurements have been performed on polycrystalline Ge-doped ${\mathrm{FeGa}}_{3}$ 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, ${x}_{C}=0.15, ^{71}(1/{T}_{1}T)$ exhibits a pronounced ${T}^{\ensuremath{-}4/3}$ power law over two orders of magnitude in temperature, which indicates three-dimensional quantum critical ferromagnetic fluctuations. Furthermore, for the ordered $x=0.2$ sample (${T}_{C}\ensuremath{\approx}6$ K), $^{71}(1/{T}_{1}T)$ could be fitted well in the frame of Moriya's self-consistent renormalization theory for weakly ferromagnetic systems with $1/{T}_{1}T\ensuremath{\sim}\ensuremath{\chi}$. In contrast to this, the low-doping regime nicely displays local moment behavior where $1/{T}_{1}T\ensuremath{\sim}{\ensuremath{\chi}}^{2}$ is valid. For $T\ensuremath{\rightarrow}0$, the Sommerfeld ratio $\ensuremath{\gamma}=(C/T)$ is enhanced $(70\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}/\mathrm{mole}\phantom{\rule{0.28em}{0ex}}{\mathrm{K}}^{2}$ for $x=0.1)$, which indicates the formation of heavy $3d$ electrons.
- Subjects :
- Physics
Condensed matter physics
02 engineering and technology
Electron
021001 nanoscience & nanotechnology
01 natural sciences
Power law
Renormalization
Magnetization
Ferromagnetism
Zero field
0103 physical sciences
Condensed Matter::Strongly Correlated Electrons
010306 general physics
0210 nano-technology
Quantum
Order of magnitude
Subjects
Details
- ISSN :
- 24699969 and 24699950
- Volume :
- 93
- Database :
- OpenAIRE
- Journal :
- Physical Review B
- Accession number :
- edsair.doi...........9854e6652109df51379676e95aca8789