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Strongly correlated thermoelectrics

Thermoelectrics with strongly correlated electrons often exhibit huge and anomalous thermoelectric power S(T) below 150 K, which makes them attractive for cooling devices. Thus, it is important to understand the observed features, which often appear very complicated. We shall explain the behavior of S(T) in intermetallic compounds with Ce, Yb or Eu ions in very simple terms, using Kondo scattering on the magnetic states with internal structure[1]. The internal structure might be due to the crystal field splitting of 4f states in Ce and Yb or to the Hund?s rule coupling in Eu or U compounds. The thermoelectric response of correlated systems close to metal-insulator transition will be discussed as well [2]. However, ZT of bulk systems with rare earth ions is never very impressive, due to large overall thermal conductivity, and it is not clear if strong correlations in bulk intermetallics can lead to useful devices. This might change in multilayers with correlated metals sandwiched between normal metals[3]. A particularly interesting behavior is expected when correlated layer is close to the metal- insulator boundary. We shall also discuss briefly our attempts to calculate the non-linear charge and heat currents of correlated systems [4]. [1] V. Zlatić, and R. Monnier, Phys. Rev. B71 (2005) 165109 ; V. Zlatić et al, cond-mat/ 0512288 (2005) ; V. Zlatić et al, Physica B 378?380 (2006) 661. [2] J. Freericks and V. Zlatić, Rev. Mod. Phys. B75 (2003) 1333. [3] J. Freericks, V. Zlatić and A. Shvaika, (2006) submitted for publication. [4] J. Freericks, V. Turkowski and V. Zlatić, (2006) submitted for publication.

Strongly correlated thermoelectrics

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