Publications

2019
M. J. Rozenberg, Schneegans, O., and Stoliar, P., “An ultra-compact leaky-integrate-and-fire model for building spiking neural networks”, Scientific Reports, vol. 9, p. 11123, 2019. WebsiteAbstract
We introduce an ultra-compact electronic circuit that realizes the leaky-integrate-and-fire model of artificial neurons. Our circuit has only three active devices, two transistors and a silicon controlled rectifier (SCR). We demonstrate the implementation of biologically realistic features, such as spike-frequency adaptation, a refractory period and voltage modulation of spiking rate. All characteristic times can be controlled by the resistive parameters of the circuit. We built the circuit with out-of-the-shelf components and demonstrate that our ultra-compact neuron is a modular block that can be associated to build multi-layer deep neural networks. We also argue that our circuit has low power requirements, as it is normally off except during spike generation. Finally, we discuss the ultimate ultra-compact limit, which may be achieved by further replacing the SCR circuit with Mott materials.
2018
O. Najera, Civelli, M., Dobrosavljevic, V., and Rozenberg, M. J., “Multiple crossovers and coherent states in a Mott-Peierls insulator”, PHYSICAL REVIEW B, vol. 97, p. 045108, 2018.Abstract
We consider the dimer Hubbard model within dynamical mean-field theory to study the interplay and competition between Mott and Peierls physics. We describe the various metal-insulator transition lines of the phase diagram and the breakdown of the different solutions that occur along them. We focus on the specific issue of the debated Mott-Peierls insulator crossover and describe the systematic evolution of the electronic structure across the phase diagram. We found that at low intradimer hopping, the emerging local magnetic moments can unbind above a characteristic singlet temperature T{*}. Upon increasing the interdimer hopping, subtle changes occur in the electronic structure. Notably, we find Hubbard bands of a mix character with coherent and incoherent excitations. We argue that this statemight be relevant formaterials such as VO2 and its signaturesmay be observed in spectroscopic studies, and possibly through pump-probe experiments.