Ultrafast Momentum-Dependent Response of Electrons in Antiferromagnetic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>EuFe</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>As</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>Driven by Optical Excitation

Rettig, Laurenz; Cortés, R.; Thirupathaiah, S.; Gegenwart, P.; Jeevan, H. S.; Wolf, Martin; Fink, J.; Bovensiepen, Uwe

doi:10.1103/physrevlett.108.097002

Cited by 82 publications

(81 citation statements)

References 36 publications

(51 reference statements)

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“…The additional component is comparable or faster than the experimental temporal resolution of ∼ 200 fs and compatible with the fastest component measured by TR-ARPES 24 . The slower, previously-observed, shows, differently from TR-ARPES, a divergent-like relaxation time at the respective magneto-structural transition temperatures.…”

Section: -16supporting

confidence: 82%

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Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

et al. 2014

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We systematically investigate temperature-and spectrally-dependent optical reflectivity dynamics in AAs2Fe2, (A=Ba, Sr and Eu), iron-based superconductors parent spin-density-wave (SDW) compounds. Two different relaxation processes are identified. The behavior of the slower process, which is strongly sensitive to the magneto-structural transition, is analyzed in the framework of the relaxation-bottleneck model involving magnons. The results are compared to recent time resolved angular photoemission results (TR-ARPES) and possible alternative assignment of the slower relaxation to the magneto-structural order parameter relaxation is discussed.

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Section: -16supporting

confidence: 82%

“…Previously it was shown, 23,25 that in the SDW state a single ∼ 1 ps relaxation component dominates the nearinfrared narrow-band optical response, while TR-ARPES experiments 24 indicate at least two distinct relaxation processes, with the longest relaxation time similar to the one observed in the optical response.…”

Section: -16mentioning

confidence: 91%

Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

et al. 2014

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“…For the time scale of the relaxation of near-E F states, we compare the present decay constants with those from previous works. The present value ∼ 0.60 ps for 10 K is close to 0.8 ps for EuFe 2 As 2 [9], 0.38 ps for Ba122 [15] . Also, it is comparable with 0.6-0.8 ps for superconducting Ba 1−x K x Fe 2 As 2 [18] estimated from time-resolved reflectivity.…”

supporting

confidence: 80%

“…Mansart et al [8] reported oscillatory components overlaid on exponential decay in the transient reflectivity spectra of Ba(Fe 0.92 Co 0.08 ) 2 As 2 . TrARPES studies on Ba/EuFe 2 As 2 [9,10] found oscillations of the chemical potential of the electrons after the pump pulse. Time-resolved x-ray diffraction experiments [11,12] measured the oscillations in the intensity of the Bragg reflections from BaFe 2 As 2 (Ba122).…”

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confidence: 99%

Ultrafast melting of spin density wave order in BaFe2As2 observed by time- and angle-resolved photoemission spectroscopy with extreme-ultraviolet higher harmonic generation

et al. 2017

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Transient single-particle spectral function of BaFe 2 As 2 , a parent compound of iron-based superconductors, has been studied by time-and angle-resolved photoemission spectroscopy with an extreme-ultraviolet laser generated by higher harmonics from Ar gas, which enables us to investigate the dynamics in the entire Brillouin zone. We observed electronic modifications from the spin-density-wave (SDW) ordered state within ∼ 1 ps after the arrival of a 1.5 eV pump pulse. We observed optically excited electrons at the zone center above E F at 0.12 ps, and their rapid decay. After the fast decay of the optically excited electrons, a thermalized state appears and survives for a relatively long time. From the comparison with the density-functional theory band structure for the paramagnetic and SDW states, we interpret the experimental observations as the melting of the SDW. Exponential decay constants for the thermalized state to recover back to the SDW ground state are ∼ 0.60 ps both around the zone center and the zone corner. PACS numbers: 74.25.Jb, 75.30.Fv, 74.70.Xa,Ultrafast phenomena in condensed matter have been the subject of intense research. In order to investigate nonequilibrium transient states in solids, the pulsed photons are divided into pump and probe portions: the pump pulses excite the system and the probe pulses measure various physical quantities of the transient states after variable delay times. On the other hand, angle-resolved photoemission spectroscopy (ARPES) is a versatile tool to study the electronic structure of solids with momentum resolution. Combining these strengths, timeand angle-resolved photoemission spectroscopy (TrARPES) was realized shortly after the advent of laser-based ARPES. TrARPES technique has been utilized to study ultrafast dynamics of various materials including charge-density-wave materials [1, 2], cuprate superconductors [3], graphene [4,5], and topological insulators [6,7].The ultrafast dynamics of iron-based superconductors (FeSCs) has also been the focus of intense research. In particular, coherent A 1g phonon oscillations of the As atoms have been observed by various pump-probe experiments. Mansart et al. [8] reported oscillatory components overlaid on exponential decay in the transient reflectivity spectra of Ba(Fe 0.92 Co 0.08 ) 2 As 2 . TrARPES studies on Ba/EuFe 2 As 2 [9, 10] found oscillations of the chemical potential of the electrons after the pump pulse. Time-resolved x-ray diffraction experiments [11,12] measured the oscillations in the intensity of the Bragg reflections from BaFe 2 As 2 (Ba122). A natural question is how the electronic system is modified concomitantly with the lattice. Since the temperature scale of the pump beam (1.5 eV ∼ 17400 K) is much higher than T N , it may drive the electronic system to undergo a phase transition to the paramagnetic (PM) state. In equilibrium, the reconstruction of the band structure across the SDW transition has been clearly observed by ARPES by changing temperature [13]. Therefore, one expects that the phase tr...

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“…Importantly, proper modeling used to analyze experimental findings should account for this behavior, especially when using strong driving fields or studying materials whose physics may manifest the effects of strong correlations. Optical reflectivity, [1][2][3][4][5] photoemission spectroscopy, [1, [6][7][8][9][10][11][12][13][14][15] and resonant x-ray scattering [16][17][18] are equilibrium methods which in the time domain are ideally suited to studying dynamics of novel ordered phases or collective excitations. [2-6, 8-10, 12-18] On sufficiently short time scales, the initial recovery in these systems following an ultrafast pump pulse should be dominated by electron-electron scattering which on its own can drive the system into a new steady-state.…”

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confidence: 99%

Electron-Mediated Relaxation Following Ultrafast Pumping of Strongly Correlated Materials: Model Evidence of a Correlation-Tuned Crossover between Thermal and Nonthermal States

et al. 2013

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We examine electron-electron mediated relaxation following excitation of a correlated system by an ultrafast electric field pump pulse. The results reveal a dichotomy in the temporal evolution as one tunes through a Mott metal-to-insulator transition: in the metallic regime relaxation can be characterized by evolution toward a steady-state electronic distribution well described by Fermi-Dirac statistics with an increased effective temperature; however, in the insulating regime this quasithermal paradigm breaks down with relaxation toward a nonthermal state with a more complicated electronic distribution that does not vary monotonically as a function of energy. We characterize the behavior by studying changes in the energy, photoemission response, and electronic distribution as functions of time. Qualitatively these results should be observable on short enough time scales that the electrons behave like an isolated system not in contact with additional degrees of freedom which can act as a thermal bath. Importantly, proper modeling used to analyze experimental findings should account for this behavior, especially when using strong driving fields or studying materials whose physics may manifest the effects of strong correlations. -6, 8-10, 12-18] On sufficiently short time scales, the initial recovery in these systems following an ultrafast pump pulse should be dominated by electron-electron scattering which on its own can drive the system into a new steady-state. Conventional analysis has been based on a quasithermal paradigm ("hot electron" or multi-temperature models); [19,20] however, there have been few tests of the validity of its underlying assumptions as a function of the strength of electronic correlations, [21] in particular as one tunes between the two regimes of a metal-to-insulator transition (MIT). [22] The MIT driven by electronic correlations usually is accompanied by a number of interesting ordering phenomena among the spin, charge, and orbital degrees of freedom in a material. An understanding of the key physics which leads to these emergent phases is often at the heart of pump-probe experiments in condensed matter systems, including high-T c cuprate superconductors, [23] nickelates, manganites, ruthenates, vanadates, [22] and even organic materials. [24][25][26] A number of experimental parameters can be used to tune across the MIT including doping and chemical substitution, pressure, and applied fields. What can be learned about the underlying physics leading to these phases as a function of these key parameters requires an understanding of the proper paradigm in which to ask the relevant questions and conduct analysis of experimental data. This is in addition to what can be learned by tuning the interaction parameters of model systems simulated in fermionic or bosonic cold atom mixtures and performing the experimental equivalent of time-resolved, pump-probe measurements. [27][28][29] In this Letter we discuss the evolution of an electronic system described in equilibrium by a simple Hamiltoni...

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Ultrafast Momentum-Dependent Response of Electrons in AntiferromagneticEuFe2As2Driven by Optical Excitation

Cited by 82 publications

References 36 publications

Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

Ultrafast melting of spin density wave order in BaFe2As2 observed by time- and angle-resolved photoemission spectroscopy with extreme-ultraviolet higher harmonic generation

Electron-Mediated Relaxation Following Ultrafast Pumping of Strongly Correlated Materials: Model Evidence of a Correlation-Tuned Crossover between Thermal and Nonthermal States

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