Ce- and Yb-based Kondo semiconductors

Takabatake, Toshiro; Iga, Fumitoshi; Yoshino, T.; Echizen, Y.; Katoh, K.; Kobayashi, K.; Higa, Motoki; Shimizu, Nobujiro; Bandô, Yoshio; Nakamoto, G.; Fujii, H.; Izawa, K.; Suzuki, Takashi; Fujita, Toshizo; Sera, Masafumi; Hiroi, Masahiko; Maezawa, K.; Mock, S.; Löhneysen, H. v.; Brückl, A.; Neumaier, K.; Andres, K.

doi:10.1016/s0304-8853(97)00842-1

Cited by 156 publications

(50 citation statements)

References 36 publications

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“…In the case of Kondo insulator CeNiSn, the inconsistent temperature dependence between ρ and R H (the decrease in ρ contradicts with the decreasing carrier number estimated from R H with decreasing temperature) has been ascribed to the increase in the carrier mobility with decreasing temperature. 34 The temperature dependences of Hall mobility µ = R H /ρ in CeOs 4 Sb 12 and CeRu 4 Sb 12 are compared in temperature dependence of µ for the two compounds are very close above ∼ 60 K, where no drastic change in the electronic density of states at E F has been reported.…”

Section: Resultsmentioning

confidence: 93%

Transport properties inCeOs4Sb12: Possibility of the ground state being semiconducting

et al. 2005

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We have measured both magnetoresistance and Hall effect in CeOs4Sb12 to clarify the large resistivity state ascribed to the Kondo insulating one and the origin of the phase transition near 0.9 K reported in the specific heat measurement. We found unusual temperature (T ) dependence both in the electrical resistivity ρ ∼ T −1/2 and the Hall coefficient RH ∼ T −1 over the wide temperature range of about two order of magnitude below ∼ 30 K, which can be explained as a combined effect of the temperature dependences of carrier density and carrier scattering by spin fluctuation. An anomaly related with the phase transition has been clearly observed in the transport properties, from which the H − T phase diagram is determined up to 14 T. Taking into account the small entropy change, the phase transition is most probably the spin density wave one. Both the electrical resistivity and Hall resistivity at 0.3 K is largely suppressed about an order of magnitude by magnetic fields above ∼ 3 T, suggesting a drastic change of electronic structure and a suppression of spin fluctuations under magnetic fields.

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Section: Resultsmentioning

confidence: 93%

Transport properties inCeOs4Sb12: Possibility of the ground state being semiconducting

et al. 2005

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“…The similar anisotropic T K has been discussed in orthorhombic CeNiSn and CeRhAs, in which no magnetic phase transition takes place. 13) In CeOs 2 Al 10 and CeRu 2 Al 10 , however, an anomalous antiferromagnetic transition appears due to a charge instability as well as CDW along the b-axis. Along the b-axis, the electronic structure is one-dimensional and the T K is lower than that in the ac-plane.…”

Section: 17)mentioning

confidence: 96%

Anisotropic Electronic Structure of the Kondo Semiconductor CeFe₂Al₁₀Studied by Optical Conductivity

2011

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We report temperature-dependent polarized optical conductivity [σ(ω)] spectra of CeFe2Al10, which is a reference material for CeRu2Al10 and CeOs2Al10 with an anomalous magnetic transition at 28 K. The σ(ω) spectrum along the b-axis differs greatly from that in the ac-plane, indicating that this material has an anisotropic electronic structure. At low temperatures, in all axes, a shoulder structure due to the optical transition across the hybridization gap between the conduction band and the localized 4f states, namely c-f hybridization, appears at 55 meV. However, the gap opening temperature and the temperature of appearance of the quasiparticle Drude weight are strongly anisotropic indicating the anisotropic Kondo temperature. The strong anisotropic nature in both electronic structure and Kondo temperature is considered to be relevant the anomalous magnetic phase transition in CeRu2Al10 and CeOs2Al10.

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“…Furthermore, when passing this crossover, optical spectral weight that is suppressed upon cooling due to the opening of the gap is recovered only at energies that are very high with respect to the charge gap. These distinct similarities of FeSi and FeSb 2 to heavy-fermion Kondo insulators [38] in both charge and spin degrees of freedom have caused great interest in this class of materials.…”

Section: Introductionmentioning

confidence: 99%

Electronic correlations inFeGa3and the effect of hole doping on its magnetic properties

et al. 2014

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We investigate signatures of electronic correlations in the narrow-gap semiconductor FeGa 3 by means of electrical resistivity and thermodynamic measurements performed on single crystals of FeGa 3 , Fe 1−x Mn x Ga 3 , and FeGa 3−y Zn y , complemented by a study of the 4d analog material RuGa 3 . We find that the inclusion of sizable amounts of Mn and Zn dopants into FeGa 3 does not induce an insulator-to-metal transition. Our study indicates that both substitution of Zn onto the Ga site and replacement of Fe by Mn introduces states into the semiconducting gap that remain localized even at highest doping levels. Most importantly, using neutron powder diffraction measurements, we establish that FeGa 3 orders magnetically above room temperature in a complex structure, which is almost unaffected by the doping with Mn and Zn. Using realistic many-body calculations within the framework of dynamical mean field theory (DMFT), we argue that while the iron atoms in FeGa 3 are dominantly in an S = 1 state, there are strong charge and spin fluctuations on short-time scales, which are independent of temperature. Further, the low magnitude of local contributions to the spin susceptibility advocates an itinerant mechanism for the spin response in FeGa 3 . Our joint experimental and theoretical investigations classify FeGa 3 as a correlated band insulator with only small dynamical correlation effects, in which nonlocal exchange interactions are responsible for the spin gap of 0.4 eV and the antiferromagnetic order. We show that hole doping of FeGa 3 leads, within DMFT, to a notable strengthening of many-body renormalizations.

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Ce- and Yb-based Kondo semiconductors

Cited by 156 publications

References 36 publications

Transport properties inCeOs4Sb12: Possibility of the ground state being semiconducting

Transport properties inCeOs4Sb12: Possibility of the ground state being semiconducting

Anisotropic Electronic Structure of the Kondo Semiconductor CeFe₂Al₁₀Studied by Optical Conductivity

Electronic correlations inFeGa3and the effect of hole doping on its magnetic properties

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Ce- and Yb-based Kondo semiconductors

Cited by 156 publications

References 36 publications

Transport properties inCeOs4Sb12: Possibility of the ground state being semiconducting

Transport properties inCeOs4Sb12: Possibility of the ground state being semiconducting

Anisotropic Electronic Structure of the Kondo Semiconductor CeFe2Al10Studied by Optical Conductivity

Electronic correlations inFeGa3and the effect of hole doping on its magnetic properties

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Product

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Anisotropic Electronic Structure of the Kondo Semiconductor CeFe₂Al₁₀Studied by Optical Conductivity