Nonequilibrium gap collapse near a first-order Mott transition

Abstract

We study the non-equilibrium dynamics of a simple model for V2O3 that consists of a quarterfilled Hubbard model for two orbitals that are split by a weak crystal field. Peculiarities of this model are: (1) a Mott insulator whose gap corresponds to transferring an electron from the occupied lower orbital to the empty upper one, rather than from the lower to the upper Hubbard sub-bands; (2) a Mott transition generically of first order even at zero temperature. We simulate by means of time-dependent Gutzwiller approximation the evolution within the insulating phase of an initial state endowed by a non-equilibrium population of electrons in the upper orbital and holes in the lower one. We find that the excess population may lead, above a threshold, to a gap-collapse and drive the insulator into the metastable metallic phase within the coexistence region around the Mott transition. This result foresees a non-thermal pathway to revert a Mott insulator into a metal. Even though this physical scenario is uncovered in a very specific toy-model, we argue it might apply to other Mott insulating materials that share similar features.

Field-Driven Mott Gap Collapse and Resistive Switch in Correlated Insulators

“…In turn, this property might also be the rationale of the abrupt gap collapse at the resistive transition, which reflects the very nature of the gap [29]. In our Mott insulator model the gap separates two bands of different orbital character, i.e.…”

“…We realize this situation including extra degrees of freedom to the Hubbard model [28,29], and we choose an orbital degree of freedom which is ubiquituously relevant in actual Mott insulating materials and increases the coexistence region with respect to the single-orbital model. In particular we consider the simplest modelling of a Mott insulator with a d-d gap [30], which we study in a slab geometry and in the presence of a constant electric field, i.e.…”

Time-dependent many-variable variational Monte Carlo method for nonequilibrium strongly correlated electron systems

“…Originally, the TDVP was applied in the field of quantum chemistry 34,35 . Recently, a similar principle has been applied to the matrix product state for quantum spin models 24,36 , the bosonic Jastrow-type wave function for the Bose-Hubbard model 21,22 and the Gutzwiller approximation for strongly correlated electron systems [37][38][39] . Although exact time evolution is unitary, and thus, the norm ψ α |ψ α is conserved, it is not necessary conserved in TDVP [Eq.…”

Dynamics of photodoped charge transfer insulators

“…3). It originates from the static Hartree-Fock attraction and is determined by the change in the local orbital occupancy [44,60,61]. The contribution of this effect to the shrinking gap is indicated in Fig.…”