Polaron formation at impurity-endowed lattices.

In semiconducting materials, lattice deformities can play the role of localizing the charge carriers. Polarons are understood as attractive interactions between charge and lattice deformations that result in a single structure composed by a charged particle surrounded by a cloud of phonons. These composite quasi-particles are vital structures when it comes to charge transport mechanism in a wide range of semiconducting materials. In the present work, we investigated the drift of an electron and the subsequent polaron formation in impurity-endowed lattices in the framework of a one-dimensional tight-binding model. Primarily, we scrutinized electronic dynamics in lattices containing two sources of disorders: a barrier and a well. The dispersion of the gamma distribution gives an idea of the extension of the disorder region in the lattice. We studied the dynamics of an injected electron interacting with the lattice vibrations where we consider, for a given degree of disorder, different velocities of the incoming particle. Our results show that there are different kinds of propagation/localization for the electron according to the assumed initial velocity. Importantly, we obtained the critical values for the impurity strength to promote the quenching of Bloch oscillations and the localization of polarons.

Bloch Oscillations in Fibonacci lattices: polaron formation.

We investigated the dynamics of an electron subjected to a uniform electric field in the scope of a tight-binding electron-phonon interacting approach. We aimed at describing the transport in a one-dimensional lattice in which the on-site energies are distributed according to a Fibonacci sequence. Within this physical picture, we obtained a novel dynamical process with no counterpart in ordered lattices. Our findings showed that in low-disorder limit, the electron performs spatial Bloch oscillations, generating, in the turning points of its trajectory, composite quasi-particles-namely, polarons. When it comes to highly disordered systems, two strongly localized polarons are formed in the region where the oscillating charge is confined, thus propagating excitations that are present in the lattice.