Subgap pumping of antiferromagnetic Mott insulators: photoexcitation mechanisms and applications

TL;DR

This paper investigates how strong ac electric fields induce photoexcitation in a 2D Mott insulator modeled by the Hubbard model, revealing new regimes beyond traditional theories and exploring experimental detection methods.

Contribution

It introduces two new photoexcitation regimes beyond the Keldysh paradigm and analyzes the real-time feedback of the Mott gap renormalization on carrier generation.

Findings

Identification of two new photoexcitation regimes

Real-time modulation of carrier generation by Mott gap renormalization

Analysis of quasiparticle momentum distribution post-drive

Abstract

We study the behavior of the 2D repulsive Hubbard model on a square lattice at half filling, under strong driving with ac electric fields, by employing a time-dependent Gaussian variational approach. Within the same theoretical framework, we analytically obtain the conventional Keldysh crossover between multiphoton and tunneling photoexcitation mechanisms, as well as two new regimes beyond the Keldysh paradigm. We discuss how dynamical renormalization of the Mott-Hubbard gap feeds back into the photoexcitation process, modulating the carrier generation rate in real time. The momentum distribution of quasiparticle excitations immediately after the drive is calculated, and shown to contain valuable information about the generation mechanism. Finally, we discuss experimental probing of the pump-induced nonequilibrium electronic state.