https://doi.org/10.1140/epjb/e2012-30060-0
Regular Article
Thermoelectric properties of the Kondo insulator FeSb2
1
Instituto de Física, Universidade Federal
Fluminense, Av. Litorânea s/n,
24210-346
Niterói, Rio de Janeiro,
Brazil
2
Departamento de Física, Universidad Nacional de
Colombia, 5997
Bogotá,
Colombia
a
e-mail: figueira@if.uff.br
Received: 24 January 2012
Published online: 20 June 2012
Recently it was shown [A. Bentien, S. Johnsen, G.K.H. Madsen, B.B. Iversen, F. Steglich, Europhys. Lett. 80, 17008 (2007)], that the strongly correlated Kondo insulator FeSb2 exhibits a colossal Seebeck coefficient; however, due to its large lattice thermal conductivity, the dimensionless thermoelectric figure of merit (zT) is only 0.005 at 12 K. This experimental result motivate us to perform a theoretical study of the thermoelectric properties of Kondo insulators, within the framework of the X-boson approach [R. Franco, M.S. Figueira, M.E. Foglio, Phys. Rev. B 66, 045112 (2002)] for the periodic Anderson model. We consider a set of parameters adequate for describing the compound FeSb2, and we calculate the resistivity, the thermoelectric power (Seebeck coefficient), the charge carrier thermal conductance, the thermoelectric factor power (zT), the Wiedemann-Franz law, the specific heat, and the Sommerfeld’s γ coefficient. The result of the colossal maximum of the Seebeck coefficient, at low temperatures, has the same order of magnitude as the experimental result [A. Bentien, S. Johnsen, G.K.H. Madsen, B.B. Iversen, F. Steglich, Europhys. Lett. 80, 17008 (2007)]. We also show that those temperature region presents an intermediate valence behavior, characterized by a moderate increase of the Sommerfeld’s γ coefficient.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2012