The seebeck coefficient of YbAl2 and YbAl3

Daal, H.J. van; Aken, Peter A. van; Buschow, K.H.J.

doi:10.1016/0375-9601(74)90870-6

Cited by 78 publications

(48 citation statements)

References 2 publications

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“…The inelastic neutron scattering data on YbAl 3 show a broad Lorentzian spectrum centered at about 540 meV 29,30 , which can be understood in terms of the Kondo effect with T K ≥ 500 K 27 . Below 100 K, the electrical resistivity of YbAl 3 decreases due to the formation of a coherent ground state and for T ≤T 0 ≃ 40 K the resistivity is a parabolic and the thermopower a linear function of temperature 25,26,31 , indicating a Fermi liquid. For T ≤ T 0 , the zero-field anomalies in χ(T ) and C V (T ) yield an enhanced effective mass 27 of the order of 1/T 0 and the neutron scattering data 29,30 show a narrow peak at about 30 meV, which is due to a hybridization gap.…”

Section: The T0 ≪ Tk Casementioning

confidence: 99%

“…In these compounds, the high-temperature resistivity is a large and slowly varying function of temperature 25,26 , the thermopower 25,26 has a broad peak around 350 K, the magnetic susceptibility and the specific heat have a broad maximum at T max ≃ 125 K, and the Hall coefficient is typical of a metal in which the c electrons scatter on local moments 9,27 . A similar high-temperature behavior is seen in YbXCu 4 (X=Cd, Mg, Zn) 28 .…”

Section: The T0 ≪ Tk Casementioning

confidence: 99%

“…The scale T 0 of a system of particles described by the periodic Anderson model close to the ground state is obtained from equations (25,29,32) as,…”

Section: The Fermi Liquid Scale T0mentioning

confidence: 99%

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Multiple temperature scales of the periodic Anderson model: Slave boson approach

Burdin

Zlatič

2009

Phys. Rev. B

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The thermodynamic and transport properties of intermetallic compounds with Ce, Eu, and Yb ions are discussed using the periodic Anderson model with an infinite correlation between f electrons. At high temperatures, these systems exhibit typical features that can be understood in terms of a single impurity Anderson or Kondo model with Kondo scale TK . At low temperatures, the normal state is governed by the Fermi liquid (FL) laws with characteristic energy scale T0. The slave boson solution of the periodic model shows that T0 and TK depend not only on the degeneracy and the splitting of the f states, the number of c and f electrons, and their coupling, but also on the shape of the conduction electrons density of states (c DOS) in the vicinity of the chemical potential.We show that the details of the band structure determine the ratio T0/TK and that the crossover between the high-and low-temperature regimes in ordered compounds is system-dependent. A sharp peak in the c DOS yields T0 ≪TK and explains the 'slow crossover' observed in YbAl3 or YbMgCu4. A minimum in the c DOS yields T0 ≫TK , which leads to the abrupt transition between the high-and low-temperature regimes in YbInCu4. In the case of CeCu2Ge2 and CeCu2Si2, where T0 ≃ TK , the slave boson solution explains the pressure experiments which reveal sharp peaks in the T 2 coefficient of the electrical resistance, A = ρ(T )/T 2 , and the residual resistance. These peaks are due to the change in the degeneracy of the f states induced by the applied pressure.The FL laws explain also the correlation between the specific heat coefficient γ = CV /T and the slope of the thermopower α(T )/T , or between γ and the A coefficient of the resistivity. For N -fold degenerate model, the FL laws explain the deviations from universal value of the Kadowaki-Woods ratio, RKW = A/γ 2 , and the ratio q = lim {T →0} α/γT . The renormalization of transport coefficients can invalidate the Wiedemann-Franz law and lead to an enhancement of the thermoelectric figure-ofmerit. We show that the low-temperature response of the periodic Anderson model can be enhanced (or reduced) with respect to the predictions based on the single-impurity models that give the same high-temperature behavior.

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Section: The T0 ≪ Tk Casementioning

confidence: 99%

Section: The T0 ≪ Tk Casementioning

confidence: 99%

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Multiple temperature scales of the periodic Anderson model: Slave boson approach

Burdin

Zlatič

2009

Phys. Rev. B

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“…The type (c) Yb systems have a nonmonotonic thermopower with a large (negative) minimum at high temperatures and a smaller one at low temperatures, but there is no sign-change. 30,31,32,33 Finally, the thermopower with a single negative peak centered around 100 K 18,30,31,34 mirrors the type (d) behavior of Ce systems. The reduction of volume by pressure or doping 30,33 stabilizes the magnetic 4f 13 configuration of Yb ions, and transforms S(T ) from, say, type (b) to type (a), from (c) to (b), or from (c) to (a).…”

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confidence: 99%

Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions

2005

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The thermoelectric properties of intermetallic compounds with Ce or Yb ions are explained by the single-impurity Anderson model which takes into account the crystal-field splitting of the 4f groundstate multiplet, and assumes a strong Coulomb repulsion which restricts the number of f electrons or f holes to n f ≤ 1 for Ce and n hole f ≤ 1 for Yb ions. Using the non-crossing approximation and imposing the charge neutrality constraint on the local scattering problem at each temperature and pressure, the excitation spectrum and the transport coefficients of the model are obtained. The thermopower calculated in such a way exhibits all the characteristic features observed in Ce and Yb intermetallics. Calculating the effect of pressure on various characteristic energy scales of the model, we obtain the (T, p) phase diagram which agrees with the experimental data on CeRu2Si2, CeCu2Si2, CePd2Si2, and similar compounds. The evolution of the thermopower and the electrical resistance as a function of temperature, pressure or doping is explained in terms of the crossovers between various fixed points of the model and the redistribution of the single-particle spectral weight within the Fermi window.

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“…The type (c) Yb systems have a nonmonotonic thermopower with a large (negative) minimum at high temperatures and a smaller one at low temperatures, but there is no sign-change. [40,42,38,41] Finally, the thermopower with a single negative peak centered around 100 K [43,40,27,38] mirrors the type (d) behavior of Ce systems. The reduction of volume by pressure or doping [42,38] stabilizes the magnetic 4f 13 configuration of Yb ions, and transforms…”

Section: Experimental Summarymentioning

confidence: 99%

Correlated thermoelectrics

Zlatić¹,

Avella²,

Mancini³

2008

AIP Conference Proceedings

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Abstract. In the first part of these lecture notes we introduce the phenomenological equations for describing the heat and charge transport in thermoelectric samples. We discuss the solution obtained for various boundary conditions that are appropriate for the homogeneous and inhomogeneous thermoelectrics. In the second part we develop the formalism for a linear-response many-body description of the transport properties of correlated electrons. By properly determining the local heat-current operator we show that the Jonson-Mahan theorem applies to the Hamiltonians that are commonly used for the intermetallic compounds with Cerium, Europium and Ytterbium ions, so the various thermal-transport coefficient integrands are related by powers of frequency. We illustrate how to use this formalism by calculating the thermoelectric properties of the periodic Anderson model and, then, show that these results explain the experimental data on heavy fermions and valence fluctuators. Finally, we calculate the thermoelectric properties of the Falicov-Kimball model and use the results to explain the anomalous features of the intermetallic compounds in which one observes the valence-change transition.

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The seebeck coefficient of YbAl2 and YbAl3

Cited by 78 publications

References 2 publications

Multiple temperature scales of the periodic Anderson model: Slave boson approach

Multiple temperature scales of the periodic Anderson model: Slave boson approach

Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions

Correlated thermoelectrics

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