Quantum magnetism and strongly correlated electrons in low dimensions

Enrico Arrigoni

Yury Anatolievich Krotov

S. Caprara, Anders Rosengren

The infinite-size version of the density-matrix renormalization-group approach in real space is applied to the Kondo lattice model in one dimension, providing a more accurate determination of the zero-temperature magnetic properties for electron densities n ⩽ 0.5. The paramagnetic state of the free model evolves into a state with ferromagnetic correlations, by increasing the strength of the Kondo coupling, in agreement with previous numerical results. The change in the magnetic properties is produced by the competition between the RKKY mechanism, which favours the paramagnetic state in the weak-coupling region, and the Kondo screening, which leads to the formation of tightly bound singlets in the strong-coupling region, enforcing ferromagnetic correlations in the system.

Assa Auerbach, F. Berruto, Luca Capriotti

Rishabh Kishore, A K Mishra

The infinite U Hubbard model, which excludes double occupancy of electrons on a lattice site, can be considered as an exactly solvable non-interacting orthofermion model. We obtained several thermodynamic and transport properties like specific heat, entropy, magnetization, magnetic susceptibility and thermoelectric power for the non-interacting orthofermions. It is found that in one dimension our results coincides with that of known exact results. In case of thermoelectric power, we have also obtained the generalized Heikes formula in high temperature limits and Stafford results at low temperatures. Since the non-interacting orthofermion model is exactly solvable in any dimension, our results can be used as a guide to ascertain the accuracy of the approximations, used to solve the finite U Hubbard model, frequently employed for the study of the strongly correlated electron systems.

Thierry Giamarchi