arXiv subjects

Kunal Mozumdar

Publications and source records attributed to Kunal Mozumdar.

3 recordsLinked to original sources

arXiv2025

Electron transport in disordered insulating lattice under nonlinear electric field

Transport in disordered systems often occurs via the variable range hopping (VRH) in the dilute carrier density limit, where electrons hop between randomly distributed localized levels. We study the nonequilibrium transport by a uniform DC electric field on a one-dimensional insulating tight-binding chain with the on-site disorder, using a disordered-lattice calculation and the coherent potential approximation. We develop a theory of electric-field-assisted variable range hopping as a mechanism for nonlinear transport in a disordered chain. Our disordered-lattice calculations of the electron propagation distance and the electron mobility determine the range of the variable range hopping as $\Delta < W \lesssim 2\Delta$ in the gap $\Delta$. We further propose a nonlinear scaling of the conductivity by an electric field by extending Mott's variable range hopping. The nonlinear conductivity of an electronic lattice model follows the scaling law $\sigma(E) \propto \exp[-(E_0/E)^{\nu}]$ with the exponent $\nu = 1/3$ in one dimension for the VRH. We also discuss the experimental relevance of temperature-dependent nonlinear current-voltage relation.

cond-mat.dis-nn↗

arXiv2025

Spectral properties of disordered insulating lattice under nonlinear electric field

Quenched disorder in a solid state system can result in Anderson localization, where electrons are exponentially localized and the system behaves like an insulator. By solving exactly a disordered electronic lattice model out of equilibrium, we investigate the effect of a DC electric field on Anderson localization in an open system, and provide a minimal platform to study disorder-nonequilibrium interplay in electronic lattice systems. We perform steady-state Keldysh Green's function calculations on an infinite lattice with a finite-range of disorder-active region that are coupled to fermion reservoirs. Our solutions out of a fully electronic model verify Mott's temperature scaling of the variable-range-hopping transport and the Lifshitz tail, well-corroborated by the coherent-potential approximation. We further reveal that a nonequilibrium electronic lattice creates a statistical evolution that shows a counterintuitive shift of the distribution edge in the opposite direction of the band edge. The rich evolution of non-thermal statistics highlights the importance of an explicit band structure and the impurity correlations in strong nonequilibrium theories.

cond-mat.dis-nn↗

arXiv2018

Frequency locking and travelling burst sequences in community structured network of inhibitory neurons with differing time-scales

We report the emergent dynamics of a community structured modular network of chaotic Hindmarsh-Rose (HR) neurons with inhibitory synapses. We find the inhibitory coupling between the neuronal modules lead to complete synchronization of neurons in a module, and also pushes modules into interesting sequences of travelling burst patterns. When dynamical time-scales vary for neurons in different modules, hence breaking the symmetry among them, we see specific sequences of travelling burst patterns that are characteristic of the time-scale mismatch and coupling strengths. Thus for a modular network with two time-scales, the neuronal communities enter into synchronized frequency locked clusters with the bursting sequences having recurring patterns. Our study provides a complete characterization of the spatio-temporal regularity in terms of frequency locking for temporal order and burst sequence patterns for spatial order in the collective dynamics of the neuronal clusters. Our results have significance in the process of information coding in terms of frequency of firing dynamics among neurons and in selective communication based on the sequences of bursts.

nlin.CD↗