arXiv subjects

Miguel M. Oliveira

Publications and source records attributed to Miguel M. Oliveira.

3 recordsLinked to original sources

arXiv2024

Voltage-Driven Breakdown of Electronic Order

The non-thermal breakdown of a Mott insulator has been a topic of great theoretical and experimental interest with technological relevance. Recent experiments have found a sharp non-equilibrium insulator-to-metal transition that is accompanied by hysteresis, a negative differential conductance and lattice deformations. However, a thorough understanding of the underlying breakdown mechanism is still lacking. Here, we examine a scenario in which the breakdown is induced by chemical pressure in a paradigmatic model of interacting spinless fermions on a chain coupled to metallic reservoirs (leads). For the Markovian regime, at infinite bias, we qualitatively reproduce several established results. Beyond infinite bias, we find a rich phase diagram where the nature of the breakdown depends on the coupling strength as the bias voltage is tuned up, yielding different current-carrying non-equilibrium phases. For weak to intermediate coupling, we find a conducting CDW phase with a bias-dependent ordering wave vector. At large interaction strength, the breakdown connects the system to a charge-separated insulating phase. We find instances of hysteretic behavior, sharp current onset and negative differential conductance. Our results can help to shed light on recent experimental findings that address current-induced Mott breakdown.

cond-mat.str-el↗

arXiv2023

Efficient quantum information probes of non-equilibrium quantum criticality

Quantum information-based approaches, in particular the fidelity, have been flexible probes for phase boundaries of quantum matter. A major hurdle to a more widespread application of fidelity and other quantum information measures to strongly correlated quantum materials is the inaccessibility of the fidelity susceptibility to most state-of-the-art numerical methods. This is particularly apparent away from equilibrium where, at present, no general critical theory is available and many standard techniques fail. Motivated by the usefulness of quantum information based measures we show that a widely accessible quantity, the single-particle affinity, is able to serve as a versatile instrument to identify phase transitions beyond Landau's paradigm. We demonstrate that it not only is able to signal previously identified non-equilibrium phase transitions but also has the potential to detect hitherto unknown phases in models of quantum matter far from equilibrium.

cond-mat.str-el↗

arXiv2019

Classical and quantum liquids induced by quantum fluctuations

Geometrically frustrated interactions may render classical ground-states macroscopically degenerate. The connection between classical and quantum liquids and how the degeneracy is affected by quantum fluctuations is, however, less well understood. We study a simple model of coupled quantum and classical degrees of freedom, the so-called Falicov-Kimball model, on a triangular lattice and away from half-filling. For weak interactions the phase diagram features a charge disordered state down to zero temperature. We provide compelling evidence that this phase is a liquid and show that it is divided by a crossover line that terminates in a quantum critical point. Our results offer a new vantage point to address how quantum liquids can emerge from their classical counterparts.

cond-mat.str-el↗