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We investigate the 2D ferromagnetic Kondo lattice model for manganites with classical corespins at Hunds rule coupling J_H=6, with antiferromagnetic superexchange 0.03 < J < 0.05. We employ canonical and grand canonical unbiased Monte Carlo simulations and find paramagnetism, weak ferromagnetism and the Flux phase, depending on doping and on J. The observed single particle spectrum in the flux phase differs from the idealized infinite lattice case, but agrees well with an idealized finite lattice case with thermal fluctuations.
Kondo insulators are emerging as a simplified setting to study both magnetic and metal-to-insulator quantum phase transitions. Here, we study a half-filled Kondo lattice model defined on a magnetically frustrated Shastry-Sutherland geometry. We deter
The effect of next-nearest-neighbor hopping $t_{2}$ on the ground-state phase diagram of the one-dimensional Kondo lattice is studied with density-matrix renormalization-group techniques and by comparing with the phase diagram of the classical-spin v
We carry out a detailed numerical study of the three-band Hubbard model in the underdoped region both in the hole- as well as in the electron-doped case by means of the variational cluster approach. Both the phase diagram and the low-energy single-pa
The paramagnetic phase diagram of the Hubbard model with nearest-neighbor (NN) and next-nearest-neighbor (NNN) hopping on the Bethe lattice is computed at half-filling and in the weakly doped regime using the self-energy functional approach for dynam
The magnetic ground state phase diagram of the ferromagnetic Kondo-lattice model is constructed by calculating internal energies of all possible bipartite magnetic configurations of the simple cubic lattice explicitly. This is done in one dimension (