Ultrafast Mott transition driven by nonlinear electron-phonon interaction

Grandi, Francesco; Li, Jiajun; Eckstein, Martin

doi:10.1103/physrevb.103.l041110

Cited by 16 publications

(8 citation statements)

References 41 publications

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“… 48 . Questions such as the consideration of additional electron–vibration interactions consistent with inversion symmetry 20 , 49 , which may aid in the stabilization of a transient superconducting state, as well as how the electron–phonon steady state exposed in this work manifests experimentally are also important open challenges and call for the development of new tools for the study of out-of-equilibrium nonlinear electron–phonon problems. An intriguing possibility is to use the information obtained here about the properties of the long-time state to motivate a variational ansatz in order to simulate the dynamics.…”

Section: Discussionmentioning

confidence: 99%

“…Optical, mode-specific excitation of atomic vibrations 3 serves as one broad class of out-of-equilibrium techniques that has been shown experimentally to lead to dramatic modifications in electronic behavior 4 – 6 , including the possible induction of a superconducting transition at a critical temperature larger than its equilibrium counterpart in K 3 C 60 7 , YBa 2 Cu 3 O 6.5 8 , and organic salts 9 . In general, optically accessible phonons are long-wavelength dipole-active modes, which typically do not couple linearly to the electron density, and therefore nonlinearities are expected to govern the dynamics in centrosymmetric systems 10 – 13 , stimulating many interesting theoretical proposals 13 – 20 . One particular mechanism 13 is based on the observation that since direct, local interaction between electrons and photo-excited phonons must depart from that of conventional linear Holstein 21 and Fröhlich 22 , 23 models, one must consider a quadratic coupling of driven phonons to the electron density.…”

Section: Introductionmentioning

confidence: 99%

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Phonon-induced disorder in dynamics of optically pumped metals from nonlinear electron-phonon coupling

et al. 2021

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The non-equilibrium dynamics of matter excited by light may produce electronic phases, such as laser-induced high-transition-temperature superconductivity, that do not exist in equilibrium. Here we simulate the dynamics of a metal driven at initial time by a spatially uniform pump that excites dipole-active vibrational modes which couple nonlinearly to electrons. We provide evidence for rapid loss of spatial coherence, leading to emergent effective disorder in the dynamics, which arises in a system unitarily evolving under a translation-invariant Hamiltonian, and dominates the electronic behavior as the system evolves towards a correlated electron-phonon long-time state, possibly explaining why transient superconductivity is not observed. Our framework provides a basis within which to understand correlation dynamics in current pump-probe experiments of vibrationally coupled electrons, highlight the importance of the evolution of phase coherence, and demonstrate that pumped electron-phonon systems provide a means of realizing dynamically induced disorder in translation-invariant systems.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phonon-induced disorder in dynamics of optically pumped metals from nonlinear electron-phonon coupling

et al. 2021

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“…In particular, the cavity is assumed to be completely lossless, and the other degrees of freedom in solids, such as phonons, are ignored. However, dissipation plays a crucial role in both solids and realistic cavities, and electron-phonon coupling is especially important in quantum materials close to a phase transition 85,86 . The questions can be phenomenologically addressed by coupling the effective models to external baths and solving them using Green's function methods, similar to the Floquet Green's function formalism 48,87 .…”

Section: Discussionmentioning

confidence: 99%

Effective theory of lattice electrons strongly coupled to quantum electromagnetic fields

Li,

Schamriß,

Eckstein

2021

Preprint

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Recent experiments have revealed the tantalizing possibility of fabricating lattice electronic systems strongly coupled to quantum fluctuations of electromagnetic fields, e.g., by means of geometry confinement from a cavity or artificial gauge fields in quantum simulators. In this work, we develop a high-frequency expansion to construct the effective models for lattice electrons strongly coupled to a continuum of off-resonant photon modes with arbitrary dispersion. The theory is nonperturbative in the light-matter coupling strength, and is therefore particularly suitable for the ultrastrong light-matter coupling regime. Using the effective models, we demonstrate how the dispersion and topology of the electronic energy bands can be tuned by the cavity. In particular, quasi-onedimensional physics can emerge in a two-dimensional square lattice due to a spatially anisotropic band renormalization, and a topologically nontrivial anomalous quantum Hall state can be induced in a honeycomb lattice when the cavity setup breaks time-reversal symmetry. We also demonstrate that the photon-mediated interaction induces an unconventional superconducting paired phase distinct from the pair-density-wave state discussed in models with truncated light-matter coupling. Finally, we study a realistic setup of a Fabry-Pérot cavity. Our work provides a systematic framework to explore the emergent phenomena due to strong light-matter coupling and points out new directions of engineering orders and topological states in solids.

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“…The SOC engineering of the order-parameter dynamics can be generalized to intertwined spin, orbital, and charge orders and may have crucial consequences on photoinduced hidden phases 57 . For this prospect, the effects of nonlocal fluctuations and electron-lattice coupling can be studied with newly developed methods, such as GW +DMFT 58,59 in the nonequilibrium regime 60 and an exact treatment of the phonon degree of freedom 61 .…”

Section: Discussionmentioning

confidence: 99%

Ultrafast dynamics in relativistic Mott insulators

Li¹,

Dasari²,

Eckstein³

2020

Preprint

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We study the photoinduced ultrafast dynamics in relativistic Mott insulators, i.e., Mott insulators with strong spin-orbit coupling. For this purpose, we consider a minimal one-band Hubbard model on lattices with square and triangular symmetries, as relevant for layered transition metal compounds such as Sr2IrO4. Depending on the lattice and the spin-orbit coupling, the systems have canted antiferromagnetic or 120 • order. They are excited by simulating a short laser pulse, and the dynamics is solved using nonequilibrium dynamical mean-field theory. The pulse generates hot carriers, which subsequently perturb the magnetic order due to the coupling between the collective order and photocarriers. We find that this dynamics, which is known form regular antiferromagnets, depends sensitively on the spatial structure of the spin-orbit coupling. On the triangular lattice, in particular, relaxation times are influenced by the spin-orbit coupling for the chiral 120 • order, while on the square lattice with canted antiferromagnetic order the spin-orbit induced canting angle remains unchanged after the excitation. Our study opens up new possibilities of controlling magnetism and exotic spin states on the ultrafast timescales.

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Ultrafast Mott transition driven by nonlinear electron-phonon interaction

Cited by 16 publications

References 41 publications

Phonon-induced disorder in dynamics of optically pumped metals from nonlinear electron-phonon coupling

Phonon-induced disorder in dynamics of optically pumped metals from nonlinear electron-phonon coupling

Effective theory of lattice electrons strongly coupled to quantum electromagnetic fields

Ultrafast dynamics in relativistic Mott insulators

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