Ultrafast evolution and transient phases of a prototype out-of-equilibrium Mott–Hubbard material

Lantz, Gabriel; Mansart, B.; Grieger, Daniel; Boschetto, D.; Nilforoushan, Niloufar; Papalazarou, E.; Moisan, Nicolas; Perfetti, L.; Jacques, Vincent; Bolloc’h, D. Le; Laulhé, Claire; Ravy, S.; Rueff, Jean‐Pascal; Glover, T. E.; Hertlein, M. P.; Hussain, Zahid; Song, Sanghoon; Chollet, Matthieu; Fabrizio, Michele; Marsi, M.

doi:10.1038/ncomms13917

Cited by 64 publications

(80 citation statements)

References 37 publications

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“…A full theoretical description of the dynamics would likely need to incorporate the electron hopping time, or transfer integral, as well as screening to fully capture the role of both energy shifts and bandwidth changes across the phase transition. The observation of a common nonthermal final state is similar to recent ultrafast pump-probe measurements on the insulating and metallic phases of the prototypical Mott-Hubbard transition in V 2 O 3 (48). Further elucidation will require more advanced theory, mapping screening and structural distortion effects onto the XUV spectrum--an exciting and tangible possibility.…”

Section: Discussionmentioning

confidence: 48%

Tracking the insulator-to-metal phase transition in VO ₂ with few-femtosecond extreme UV transient absorption spectroscopy

Jager

Ott

Kraus

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

132

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Coulomb correlations can manifest in exotic properties in solids, but how these properties can be accessed and ultimately manipulated in real time is not well understood. The insulator-to-metal phase transition in vanadium dioxide (VO 2 ) is a canonical example of such correlations. Here, few-femtosecond extreme UV transient absorption spectroscopy (FXTAS) at the vanadium M 2,3 edge is used to track the insulator-to-metal phase transition in VO 2 . This technique allows observation of the bulk material in real time, follows the photoexcitation process in both the insulating and metallic phases, probes the subsequent relaxation in the metallic phase, and measures the phasetransition dynamics in the insulating phase. An understanding of the VO 2 absorption spectrum in the extreme UV is developed using atomic cluster model calculations, revealing V 3+ /d 2 character of the vanadium center. We find that the insulator-to-metal phase transition occurs on a timescale of 26 ± 6 fs and leaves the system in a longlived excited state of the metallic phase, driven by a change in orbital occupation. Potential interpretations based on electronic screening effects and lattice dynamics are discussed. A Mott-Hubbard-type mechanism is favored, as the observed timescales and d 2 nature of the vanadium metal centers are inconsistent with a Peierls driving force. The findings provide a combined experimental and theoretical roadmap for using time-resolved extreme UV spectroscopy to investigate nonequilibrium dynamics in strongly correlated materials.he Coulomb interaction of charges in a solid depends sensitively on local screening, bonding structure, and orbital occupancy. These electronic correlation effects are known to manifest themselves in unusual properties, such as superconductivity, colossal magnetoresistance, and insulator-to-metal phase transitions (IMTs), which can be switched on or off via small perturbations. Understanding if and how these correlation-driven properties can be manipulated in real time will open the door to using these materials as ultrafast photonic switches and will establish the electronic speed limits for next-generation devices (1-3).Following the real-time dynamics of carrier interactions necessarily requires time-resolving the excitation and relaxation of electron correlations. Studies at longer timescales are complicated by simultaneous effects of structural distortion together with carrier screening and thermalization. In contrast, few-femtosecond extreme UV absorption spectroscopy (FXTAS) provides temporal resolution close to the Fourier limit for single-photon excitation with broadband visible light. It has the capability to separate electronic and structural effects on the basis of their intrinsic timescales and can isolate early-time electronic dynamics spectroscopically via atom-specific core-level electronic transitions (4, 5). Previous few-femtosecond and attosecond measurements of electron dynamics in solid-state systems have been restricted to simple band insulators or semiconductors and...

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Section: Discussionmentioning

confidence: 48%

Tracking the insulator-to-metal phase transition in VO ₂ with few-femtosecond extreme UV transient absorption spectroscopy

Jager

Ott

Kraus

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

132

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“…We shall use Y 1 (ω) as first estimate of the error one can do by replacing the internal vector potential with the external one in the minimal coupling scheme (5).…”

Section: Discussionmentioning

confidence: 99%

Misuse of the minimal coupling to the electromagnetic field in quantum many-body systems

2020

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Consistency with the Maxwell equations determines how matter must be coupled to the electromagnetic field (EMF) within the minimal coupling scheme. Specifically, if the Hamiltonian includes just a short-range repulsion among the conduction electrons, as is commonly the case for models of correlated metals, those electrons must be coupled to the full internal EMF, whose longitudinal and transverse components are self-consistently related to the electron charge and current densities through Gauss's and circuital laws, respectively. Since such self-consistency relation is hard to implement when modelling the non-equilibrium dynamics caused by the EMF, as in pump-probe experiments, it is common to replace in model calculations the internal EMF by the external one.Here we show that such replacement may be extremely dangerous, especially when the frequency of the external EMF is below the intra-band plasma edge.

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“…In particular, time-resolved measurements in different energy ranges have contributed to the understanding of insulator-to-metal transitions (IMTs) in vanadium dioxide (VO 2 ) and vanadium sesquioxide (V 2 O 3 ) as a function of temperature, pressure and doping [7][8][9][10][11][12][13][14][15] . These measurements have also shed light onto the nature of the different insulating phases in both systems 8,[16][17][18] , and onto the electron-phonon coupling driven acoustic response in V 2 O 3 8,9 .…”

Section: Introductionmentioning

confidence: 99%

Ultrafast electron-lattice coupling dynamics in VO2 and V2O3 thin films

et al. 2017

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Ultrafast optical pump -optical probe and optical pump -terahertz probe spectroscopy were performed on vanadium dioxide (VO 2 ) and vanadium sesquioxide (V 2 O 3 ) thin films over a wide temperature range. A comparison of the experimental data from these two different techniques and two different vanadium oxides, in particular a comparison of the spectral weight oscillations generated by the photoinduced longitudinal acoustic modulation, reveals the strong electron-phonon coupling that exists in both materials. The low energy Drude response of V 2 O 3 appears more amenable than VO 2 to ultrafast strain control. Additionally, our results provide a measurement of the temperature dependence of the sound velocity in both systems, revealing a four-to fivefold increase in VO 2 and a three-to fivefold increase in V 2 O 3 across the insulator-to-metal phase transition. Our data also confirm observations of strong damping and phonon anharmonicity in the metallic phase of VO 2 , and suggest that a similar phenomenon might be at play in the metallic phase of V 2 O 3 . More generally, our simple table-top approach provides relevant and detailed information about dynamical lattice properties of vanadium oxides, paving the way to similar studies in other complex materials.2

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Ultrafast evolution and transient phases of a prototype out-of-equilibrium Mott–Hubbard material

Cited by 64 publications

References 37 publications

Tracking the insulator-to-metal phase transition in VO ₂ with few-femtosecond extreme UV transient absorption spectroscopy

Tracking the insulator-to-metal phase transition in VO ₂ with few-femtosecond extreme UV transient absorption spectroscopy

Misuse of the minimal coupling to the electromagnetic field in quantum many-body systems

Ultrafast electron-lattice coupling dynamics in VO2 and V2O3 thin films

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Ultrafast evolution and transient phases of a prototype out-of-equilibrium Mott–Hubbard material

Cited by 64 publications

References 37 publications

Tracking the insulator-to-metal phase transition in VO 2 with few-femtosecond extreme UV transient absorption spectroscopy

Tracking the insulator-to-metal phase transition in VO 2 with few-femtosecond extreme UV transient absorption spectroscopy

Misuse of the minimal coupling to the electromagnetic field in quantum many-body systems

Ultrafast electron-lattice coupling dynamics in VO2 and V2O3 thin films

Contact Info

Product

Resources

About

Tracking the insulator-to-metal phase transition in VO ₂ with few-femtosecond extreme UV transient absorption spectroscopy

Tracking the insulator-to-metal phase transition in VO ₂ with few-femtosecond extreme UV transient absorption spectroscopy