Nonthermal switching of charge order: Dynamical slowing down and optimal control

Schüler, Michael; Murakami, Yuta; Werner, Philipp

doi:10.1103/physrevb.97.155136

Cited by 12 publications

(9 citation statements)

References 75 publications

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“…Divergent slow dynamics also characterize the ultrafast suppression of the nematic electronic order in FeSe (Shimojima et al, 2019) and in iron pnictides (Patz et al, 2014). This seemingly universal behavior in out-of-equilibrium second-order phase 0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 1.0 0 transitions has been discussed in the time-dependent GL framework (Dolgirev et al, 2020), by stochastic Langevin equations describing the relevant subsystems (Sieberer et al, 2016), and by non-equilibrium Green's functions (Schüler et al, 2018).…”

Section: Out-of-equilibrium Critical Behaviormentioning

confidence: 97%

Colloquium: Nonthermal pathways to ultrafast control in quantum materials

Torre

Kennes²,

Claassen³

et al. 2021

Rev. Mod. Phys.

250

128

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We review recent progress in utilizing ultrafast light-matter interaction to control the macroscopic properties of quantum materials. Particular emphasis is placed on photoinduced phenomena that do not result from ultrafast heating effects but rather emerge from microscopic processes that are inherently nonthermal in nature. Many of these processes can be described as transient modifications to the free energy landscape resulting from the redistribution of quasiparticle populations, the dynamical modification of coupling strengths and the resonant driving of the crystal lattice. Other pathways result from the coherent dressing of a material's quantum states by the light field. We discuss a selection of recently discovered effects leveraging these mechanisms, as well as the technological advances that led to their discovery. A road map for how the field can harness these nonthermal pathways to create new functionalities is presented.

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Section: Out-of-equilibrium Critical Behaviormentioning

confidence: 97%

Colloquium: Nonthermal pathways to ultrafast control in quantum materials

Torre

Kennes²,

Claassen³

et al. 2021

Rev. Mod. Phys.

250

128

View full text Add to dashboard Cite

show abstract

“…In the present study, the nonequilibrium transition is between two long-lived nonthermal states with and without AFM order, and the (almost) diverging timescale is associated with the melting of the order, or the relaxation into the trapped AFM state [61]. The universal character of this type of dynamical phase transition is exemplified by its appearance in a broad range of systems, including superconductors [62][63][64][65], excitonic insulators [66], antiferromagnetic [12,61], ferromagnetic [11,60,67] and charge-ordered [13] systems. Fig.…”

Section: /T Cmentioning

confidence: 78%

Truncating the memory time in nonequilibrium dynamical mean field theory calculations

Schüler¹,

Eckstein²,

Werner³

2018

Phys. Rev. B

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The nonequilibrium Green's functions (NEGF) approach is a versatile theoretical tool, which allows to describe the electronic structure, spectroscopy and dynamics of strongly correlated systems. The applicability of this method is, however, limited by its considerable computational cost. Due to the treatment of the full two-time dependence of the NEGF the underlying equations of motion involve a long-lasting non-Markovian memory kernel that results in at least a 3 scaling in the number of time points . The system's memory time is, however, reduced in the presence of a thermalizing bath. In particular, dynamical mean-field theory (DMFT) -one of the most successful approaches to strongly correlated lattice systems -maps extended systems to an effective impurity coupled to a bath. In this work, we systematically investigate how the memory time can be truncated in nonequilibrium DMFT simulations of the Hubbard and Hubbard-Holstein model. We show that suitable truncation schemes, which substantially reduce the computational cost, result in excellent approximations to the full time evolution. This approach enables the propagation to longer times, making fundamental processes like prethermalization and the final stages of thermalization accessible to nonequilibrium DMFT.

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“…The bath introduces a suitable decay channel, and we identified separate decay timescales for the excitonic order parameter related to dephasing and thermalization. While we have concentrated on the EI system, we expect our findings to also be general for other symmetry-broken or ordered-phase systems, including, e.g., superconducting [9,11,12,108,109] or charge-density-wave order [110][111][112].…”

Section: Discussionmentioning

confidence: 69%

Comparing the generalized Kadanoff-Baym ansatz with the full Kadanoff-Baym equations for an excitonic insulator out of equilibrium

Tuovinen¹,

Golež²,

Eckstein³

et al. 2020

Phys. Rev. B

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We investigate out-of-equilibrium dynamics in an excitonic insulator (EI) with a finite-momentum pairing perturbed by a laser-pulse excitation and a sudden coupling to fermionic baths. The transient dynamics of the excitonic order parameter is resolved using the full nonequilibrium Green's function approach and the generalized Kadanoff-Baym ansatz (GKBA) within the second-order Born approximation. The comparison between the two approaches after a laser-pulse excitation shows a good agreement in the weak and the intermediate photodoping regime. In contrast, the laser-pulse dynamics resolved by the GKBA does not show a complete melting of the excitonic order after a strong excitation. Instead we observe persistent oscillations of the excitonic order parameter with a predominant frequency given by the renormalized equilibrium band gap. This anomalous behavior can be overcome within the GKBA formalism by coupling to an external bath, which leads to a transition of the EI system toward the normal state. We analyze the long-time evolution of the system and distinguish decay timescales related to dephasing and thermalization.

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Nonthermal switching of charge order: Dynamical slowing down and optimal control

Cited by 12 publications

References 75 publications

Colloquium: Nonthermal pathways to ultrafast control in quantum materials

Colloquium: Nonthermal pathways to ultrafast control in quantum materials

Truncating the memory time in nonequilibrium dynamical mean field theory calculations

Comparing the generalized Kadanoff-Baym ansatz with the full Kadanoff-Baym equations for an excitonic insulator out of equilibrium

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