Dynamics of screening in photodoped Mott insulators

Golež, Denis; Eckstein, Martin; Werner, Philipp

doi:10.1103/physrevb.92.195123

Cited by 48 publications

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“…In particular, there is a pronounced maximum at the Γ-point at ω ≈ U and dispersive bands with a minimal energy around the X-point. Immediately after the excitation the weight in the sub-gap region is increased in agreement with previous EDMFT results [36], see Fig. 4(e).…”

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confidence: 92%

“…3(d). In agreement with the previous EDMFT results, low energy screening channels appear as a consequence of photodoping [36]. The main difference in GW +EDMFT is that the imaginary part of W R (t, ω) changes sign as the system evolves into the population-inverted state.…”

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confidence: 90%

“…3(a). In agreement with the evolution of the kinetic energy, we observe a shift of the excited doublons toward higher energies, in contrast to previous DMFT and EDMFT studies [12,36,41] that consistently showed a relaxation of doublons to the lower edge of the upper Hubbard band. This GW +EDMFT evolution eventually results in a population inversion, as illustrated by the distribution function f (t, Fig.…”

supporting

confidence: 88%

“…Furthermore, the kinetic energy increases during the relaxation process, illustrated in Fig. 2(b), which is also intriguingly different from the behavior reported in previous photodoping studies [12,36,41].In order to gain further insight into this intermediate V regime we calculate the time and frequency-resolved spectral function of the system. After the pulse excitation of the system the spectral function A(t, ω) = − 1 π Im[G R (t, ω)] remains almost unchanged, while the occupied density of states…”

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confidence: 58%

“…In the present case, the relevant strength λ of the electron-boson coupling can be estimated from the density of states D(t, ω) of the bosonic modes in the auxiliary Anderson-Holstein impurity model (i.e., the boson-mediated density-density interaction interaction) as λ = dω |ImD(ω)|ω [23,36]. As shown in Fig.…”

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Nonequilibrium GW+EDMFT : Antiscreening and Inverted Populations from Nonlocal Correlations

et al. 2017

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We study the dynamics of screening in photo-doped Mott insulators with long-ranged interactions using a nonequilibrium implementation of the GW plus extended dynamical mean field theory (GW +EDMFT) formalism. Our study demonstrates that the complex interplay of the injected carriers with bosonic degrees of freedom (charge fluctuations) can result in long-lived transient states with properties that are distinctly different from those of thermal equilibrium states. Systems with strong nonlocal interactions are found to exhibit a self-sustained population inversion of the doublons and holes. This population inversion leads to low-energy antiscreening which can be detected in time-resolved electron-energy loss spectra. PACS numbers: 71.10.Fd,72.10.Di,05.70.Ln The development of time-resolved spectroscopic techniques provided important insights into the properties of complex materials [1][2][3][4][5], where charge, spin, orbital and lattice degrees of freedom are intertwined. A particularly exciting prospect is the nonequilibrium manipulation of material properties on electronic time scales, and the exploration of transient states that cannot be realized under equilibrium conditions. Prominent examples of this development are the laserinduced switching to a hidden state [6] in 1T-TaS 2 , and an apparent increase of the superconducting T c in phonon-driven cuprates and fulleride superconductors [7, 8].Essential for the understanding of such experiments and phenomena is the ability to simulate relevant model systems using techniques that capture correlation effects in highly nonthermal states. Of particular importance is a proper description of the time-dependent screening processes, which determine the interaction parameters in such model Hamiltonians. The photo-induced change of screening was considered, e.g., as the cause of the collapse of the band gap in VO 2 [9], or for an enhancement of excitonic order in Ta 2 NiSe 5 [10]. Moreover, screening originates from charge fluctuations, which, similar to other bosonic modes like phonons [11][12][13][14] or spin fluctuations [15,16], profoundly affect the relaxation pathway of the electronic distribution. As we will show in this paper, the fermionic dynamics and the bosonic screening modes are strongly coupled, so that their mutual interplay can lead to long-lived transient states which are entirely different from those characterizing equilibrium phases. These non-thermal states, with partially inverted populations, thus provide an intriguing pathway to novel light-induced properties.A promising formalism to address these questions in strongly correlated solids is the combination of the GW method and extended dynamical mean field theory (GW +EDMFT) [17,18]. Hedin's GW method [19,20] is a weak coupling approach in which the self-energy is approximated by the product of the Green's function G and the screened interaction W . It captures nonlocal physics resulting from charge fluctuations, like screening, plasmonic collective modes and charge density waves. It however f...

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