Ferromagnetic Instability in a Doped Band-Gap Semiconductor FeGa${}_3$

Abstract

We report the effects of electron doping on the ground state of a diamagnetic semiconductor FeGa${}_3$ with a band gap of 0.5 eV. By means of electrical resistivity, magnetization and specific heat measurements we have found that gradual substitution of Ge for Ga in FeGa${}_{3-y}$Ge${}_y$ yields metallic conduction at a very small level of $y=0.006$, then induces weak ferromagnetic (FM) order at $y=0.13$ with a spontaneous moment of 0.1 ${\mu }_B$/Fe and a Curie temperature $T_C=3.3$ K, which continues increasing to $T_C=75$ K as doping reaches $y=0.41$. The emergence of the FM state is accompanied by quantum critical behavior as observed in the specific heat, $C/T\propto -$ln$T$, and in the magnetic susceptibility, $M/B\propto T^{-4/3}$. At $y=0.09$, the specific heat divided by temperature $C/T$ reaches a large value of 70 mJ/K${}^2$molFe, twice as large as that reported on FeSi${}_{1-x}$Ge${}_x$ for $x_c=0.37$ and Fe${}_{1-x}$Co${}_x$Sb${}_2$ for $x_c=0.3$ at their respective FM quantum critical points. The critical concentration $y_c=0.13$ in FeGa${}_{3-y}$Ge${}_y$ is quite small, despite the fact that its band gap is one order of magnitude larger than those in FeSi and FeSb${}_2$. In contrast, no FM state emerges by substituting Co for Fe in Fe${}_{1-x}$Co${}_x$Ga${}_3$ in the whole range $0\le x\le 1$, although both types of substitution should dope electrons into FeGa${}_3$. The FM instability found in FeGa${}_{3-y}$Ge${}_y$ indicates that strong electron correlations are induced by the disturbance of the Fe 3d - Ga 4p hybridization.

21 pages, 11 figures, accepted for publication in Phys. Rev. B

References in corpus (4)

• Temperature dependent correlations in covalent insulators
• The semiconductor-to-ferromagnetic-metal transition in FeSb2
• Anisotropy in magnetic and transport properties of Fe1-xCoxSb2
• Weak Ferromagnetism in Fe1-xCoxSb2

Cited by in corpus (11)

• Phonon-drag effect in FeGa3
• Interplay between localized and itinerant magnetism in Co substituted FeGa${}_3$
• Electronic correlations in FeGa${}_3$ and the effect of hole doping on its magnetic properties
• Itinerant origin of the ferromagnetic quantum critical point in Fe(Ga,Ge)3
• Towards ferromagnetic quantum criticality in FeGa3-xGex: 71Ga NQR as a zero field microscopic probe
• Itinerant magnetism in doped semiconducting beta-FeSi2 and CrSi2
• Emergence of competing magnetic interactions induced by Ge doping in the semiconductor FeGa3
• High pressure studies on properties of FeGa3: role of on-site coulomb correlation
• Magnetic order of intermetallic FeGa${}_{3-y}$Ge${}_y$ studied by $\mu$SR and ${}^{57}$Fe Mössbauer spectroscopy
• Structural and electronic properties of Fe(AlxGa1-x)3 system
• 121,123Sb NQR as a microscopic probe in Te doped correlated semimetal FeSb2 : emergence of electronic Griffith phase, magnetism and metallic behavior %