Thermopower Calculated for the Hubbard Model of the Doped Mott Insulatorsby Tommy on 20/09/2012
Entropy, frustration and large thermopower of doped Mott insulators on the fcc lattice,
Louis-François Arsenault, B. Sriram Shastry, Patrick Sémon and A.-M. S. Tremblay,
Electronic frustration and strong correlations may lead to large Seebeck coefficients. To understand this physics on general grounds, we compute the thermopower of the one-band Hubbard model on the 3-dimensional fcc lattice over the whole range of fillings for intermediate and large interaction strength. Dynamical mean-field theory shows that when the density approaches half-filling, the fcc lattice at strong coupling exhibits a large low temperature Seebeck coefficient S. The largest effect occurs as one approaches n=1 from dopings where electronic frustration is maximized. The high-frequency limit of the thermopower and the Kelvin limit are both used to provide physical insight as well as practical tools to estimate the thermopower. The high-frequency limit gives a reliable estimate of the DC limit at low temperature when the metal becomes coherent. By contrast, the Kelvin approach is useful in the strongly interacting case at high temperature when transport is incoherent. The latter result shows that in doped Mott insulators at high temperature and strong coupling the thermopower can be understood on entropic grounds.
Optimal doping and entropic origin of giant thermopower in doped Mott insulators,
Louis-Francois Arsenault, B. Sriram Shastry, Patrick Semon and A.-M. S. Tremblay
We study the Seebeck coefficient of the Hubbard model on the 3-dimensional FCC lattice at various fillings and interaction strength using dynamical mean-field theory for the one-band Hubbard model. It is shown to exhibit a giant Seebeck coefficient at strong coupling that feeds off the electronic frustration of the FCC lattice. In addition, we find that there is an optimal doping. The high-frequency limit of the thermopower gives a reliable estimate of the DC limit at weak to intermediate couplings, while the Kelvin approach is useful in the strongly interacting case. The latter result show that in doped Mott insulators, the enhancement of the thermopower can be understood on entropic grounds for all temperatures.
Update : This previous paper has been withdrawn.
This paper has been withdrawn by the authors because the results were incorrect due to the use of an impurity solver that fails at large interaction strength and above half-filling. This led, first, to the development of a new impurity solver (arXiv:1202.5814 or Phys.Rev. B 86, 085133 (2012)) and, second, to a complete revision of the thermopower results with different conclusions. Therefore a new paper on thermopower was submitted (arXiv:1209.4349) and the present one withdrawn.