arXiv subjects

Marcelo J. Rozenberg

Publications and source records attributed to Marcelo J. Rozenberg.

25 records · Page 2Linked to original sources

arXiv2004

Strong electron correlation effects in non-volatile electronic memory devices

We investigate hysteresis effects in a model for non-volatile memory devices. Two mechanisms are found to produce hysteresis effects qualitatively similar to those often experimentally observed in heterostructures of transition metal oxides. One of them is a novel switching effect based on a metal-insulator transition due to strong electron correlations at the dielectric/metal interface. The observed resistance switching phenomenon could be the experimental realisation of a novel type of strongly correlated electron device.

cond-mat.str-el↗

arXiv2004

Dynamical Mean Field Theory with the Density Matrix Renormalization Group

A new numerical method for the solution of the Dynamical Mean Field Theory's self-consistent equations is introduced. The method uses the Density Matrix Renormalization Group technique to solve the associated impurity problem. The new algorithm makes no a priori approximations and is only limited by the number of sites that can be considered. We obtain accurate estimates of the critical values of the metal-insulator transitions and provide evidence of substructure in the Hubbard bands of the correlated metal. With this algorithm, more complex models having a larger number of degrees of freedom can be considered and finite-size effects can be minimized.

cond-mat.str-el↗

arXiv1999

The Finite Temperature Mott Transition in the Hubbard Model in Infinite Dimensions

We study the second order finite temperature Mott transition point in the fully frustrated Hubbard model at half filling, within Dynamical Mean Field Theory. Using quantum Monte Carlo simulations we show the existence of a finite temperature second order critical point by explicitly demonstrating the existence of a divergent susceptibility as well as by finding coexistence in the low temperature phase. We determine the location of the finite temperature Mott critical point in the (U,T) plane. Our study verifies and quantifies a scenario for the Mott transition proposed in earlier studies (Reviews of Modern Physics 68, 13, 1996) of this problem.

cond-mat.str-el↗

arXiv1997

A scenario for the electronic state in the manganase perovskites: the orbital correlated metal

We argue that, at low temperatures and well into the ferromagnetic phase, the physics of the manganase perovskites may be characterized by a correlated metallic state near a metal insulator transition where the orbital degrees of freedom play a main role. This follows from the observation that a two-band degenerate Hubbard model under a strong magnetic field can be mapped onto a para-orbital single band model. We solve the model numerically using the quantum Monte Carlo technique within a dynamical mean field theory which is exact in the limit of large lattice connectivity. We argue that the proposed scenario may allow for the qualitative interpretation of a variety of experiments which were also observed in other (early) transition metal oxides.

cond-mat.str-el↗

arXiv1996

Integer filling metal insulator transitions in the degenerate Hubbard model

We obtain exact numerical solutions of the degenerate Hubbard model in the limit of large dimensions (or large lattice connectivity). Successive Mott-Hubbard metal insulator transitions at integer fillings occur at intermediate values of the interaction and low enough temperature in the paramagnetic phase. The results are relevant for transition metal oxides with partially filled narrow degenerate bands.

cond-mat.str-el↗

arXiv1995

Zero-temperature magnetism in the periodic Anderson model in the limit of large dimensions

We study the magnetism in the periodic Anderson model in the limit of large dimensions by mapping the lattice problem into an equivalent local impurity self-consistent model. Through a recently introduced algorithm based on the exact diagonalization of an effective cluster hamiltonian, we obtain solutions with and without magnetic order in the half-filled case. We find the exact AFM-PM phase boundary which is shown to be of $2^{nd}$ order and obeys $\frac{V^2}{U} \approx const.$ We calculate the local staggered moments and the density of states to gain insights on the behavior of the AFM state as it evolves from itinerant to a local-moment magnetic regime

cond-mat↗

arXiv1994

The Metal-Insulator Transition in the Hubbard Model at Zero Temperature II

We study the metal-to-insulator transition of the Hubbard model at zero temperatures in infinite dimensions. The coexistence of metallic and insulating solutions for a finite range of the interaction is established. It is shown that the metallic solution is lower in energy for any interaction in the coexistence region and that the transition is of second order.

cond-mat↗