arXiv subjects

I. Gonzalez

Publications and source records attributed to I. Gonzalez.

7 recordsLinked to original sources

arXiv2012

Nonmesonic Hyperon Weak Decay Spectra in $^{12}_Λ$C}

We study the nonmesonic weak decay (NMWD) $ΛN \to nN$ of the ${}^{12}_Λ C$ hypernucleus induced by the nucleon $N=n,p$ with transition rate $Γ_N$. The nuclear process is described by the interplay of two models; one describing the NMWD of hyperon $Λ$ in the nuclear environment, and the other taking into account the Final State Interaction (FSI) of the two outgoing nucleons with the residual nucleus. The first one is done in the framework of the Independent-Particle Shell-Model (IPSM), with the decay dynamics represented by the exchange of $π+ η+ K+ρ+ω+K^*$ mesons with usual parametrization. For the second one is used a time dependent multicollisional intranuclear cascade schema (implemented in the CRISP code - Collaboration Rio-São Paulo). The results obtained for inclusive and exclusive kinetic energy spectra, and the angular correlation are compared with recent data from KEK and FINUDA experiments. The calculated ratio $(Γ_n / Γ_p)^{\partial{\tiny FSI}}$, between the numbers of emitted back-to-back $nn$ and $np$ pairs, is in good agreement with the experimental data.

nucl-th↗

arXiv2010

Non-equilibrium electronic transport in a one-dimensional Mott insulator

We calculate the non-equilibrium electronic transport properties of a one-dimensional interacting chain at half filling, coupled to non-interacting leads. The interacting chain is initially in a Mott insulator state that is driven out of equilibrium by applying a strong bias voltage between the leads. For bias voltages above a certain threshold we observe the breakdown of the Mott insulator state and the establishment of a steady-state electronic current through the system. Based on extensive time-dependent density matrix renormalization group simulations, we show that this steady-state current always has the same functional dependence on voltage, independent of the microscopic details of the model and relate the value of the threshold to the Lieb-Wu gap. We frame our results in terms of the Landau-Zener dielectric breakdown picture. Finally, we also discuss the real-time evolution of the current, and characterize the current-carrying state resulting from the breakdown of the Mott insulator by computing the double occupancy, the spin structure factor, and the entanglement entropy.

cond-mat.str-el↗

arXiv2008

Excitons in the One-Dimensional Hubbard Model: a Real-Time Study

We study the real-time dynamics of a pair hole/doubly-occupied-site, namely a holon and a doublon, in a 1D Hubbard insulator with on-site and nearest-neighbor Coulomb repulsion. Our analysis shows that the pair is long-lived and the expected decay mechanism to underlying spin excitations is actually inefficient. For a nonzero inter-site Coulomb repulsion, we observe that part of the wave-function remains in a bound state. Our study also provides insight on the holon-doublon propagation in real space. Due to the one-dimensional nature of the problem, these particles move in opposite directions even in the absence of an applied electric field. The potential relevance of our results to solar cell applications is discussed.

cond-mat.str-el↗

arXiv2008

Charge transfer in heterostructures of strongly correlated materials

In this manuscript, recent theoretical investigations by the authors in the area of oxide multilayers are briefly reviewed. The calculations were carried out using model Hamiltonians and a variety of non-perturbative techniques. Moreover, new results are also included here. They correspond to the generation of a metallic state by mixing insulators in a multilayer geometry, using the Hubbard and Double Exchange models. For the latter, the resulting metallic state is also ferromagnetic. This illustrates how electron or hole doping via transfer of charge in multilayers can lead to the study of phase diagrams of transition metal oxides in the clean limit. Currently, these phase diagrams are much affected by the disordering standard chemical doping procedure, which introduces quenched disorder in the material.

cond-mat.str-el↗

arXiv2003

Stabilization of magnetic polarons in antiferromagnetic semiconductors by extended spin distortions

We study the problem of a magnetic polaron in an antiferromagnetic semiconductor (ferron). We obtain an analytical solution for the distortion produced in the magnetic structure of the d-spins due to the presence of a charge carrier bound to an impurity. The region in which the charge carrier is trapped is of the order of the lattice constant (small ferron) but the distortion of the magnetic structure extends over much larger distance. It is shown that the presence of this distortion makes the ferron more stable, and introduces a new length scale in the problem.

cond-mat.str-el↗

arXiv2002

On the absence of conduction electrons in the antiferromagnetic part of the phase-separated states in magnetic semiconductors

We have calculated the energies of the phase-separated states for degenerate antiferromagnetic semiconductors including the possibility of the existence of conduction electrons in the antiferromagnetic part of the phase-separated states. It is demonstrated that, at T=0, the minimum energy corresponds to a droplet phase with absence of electrons in the antiferromagnetic part.

cond-mat.str-el↗

arXiv2002

Phase diagram as a function of temperature and magnetic field for magnetic semiconductors

Using an extension of the Nagaev model of phase separation (E.L. Nagaev, and A.I. Podel'shchikov, Sov. Phys. JETP, 71 (1990) 1108), we calculate the phase diagram for degenerate antiferromagnetic semiconductors in the T-H plane for different current carrier densities. Both, wide-band semiconductors and 'double-exchange' materials, are investigated.

cond-mat.str-el↗