Comparing the oscillation phase in optical pump-probe spectra to ultrafast x-ray diffraction in the metal-dielectric SrRuO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>/SrTiO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>superlattice

Bojahr, André; Schick, Daniel; Maerten, Lena; Herzog, Marc; Vrejoiu, Ionela; Schmising, Clemens von Korff; Milne, Christopher J.; Johnson, S. L.; Bargheer, Matias

doi:10.1103/physrevb.85.224302

Cited by 29 publications

(33 citation statements)

References 39 publications

(45 reference statements)

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“…[18][19][20][21] Consequently, we acquired information both on in-and out-of-plane structure dynamics utilizing this time-resolved version of reciprocal-space mapping. The temporal overlap of the optical pump and x-ray probe pulses was determined in an independent cross-correlation experiment [22] and was set to the delay 0 ps.…”

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confidence: 99%

Following Strain-Induced Mosaicity Changes of Ferroelectric Thin Films by Ultrafast Reciprocal Space Mapping

et al. 2013

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We investigate coherent phonon propagation in a thin film of ferroelectric PbZr0.2Ti0.8O3 (PZT) by ultrafast x-ray diffraction (UXRD) experiments, which are analyzed as time-resolved reciprocal space mapping (RSM) in order to observe the in-and out-of-plane structural dynamics simultaneously. The mosaic structure of the PZT leads to a coupling of the excited out-of-plane expansion to in-plane lattice dynamics on a picosecond timescale, which is not observed for out-of-plane compression.Oxides are attractive constituents of future nanoelectronic devices, because of their broad spectrum of outstanding physical properties, such as ferroelectricity and ferromagnetism, and owing to the progress made in the fabrication of high quality epitaxial heterostructures.[1] Epitaxial strain engineering and the careful choice of mechanical and electrical boundary conditions enable a direct influence on these functionalities.[2-6] Structural defects and nanoscale inhomogeneities, such as dislocations and domains, typically affect the properties of functional oxides and have been extensively studied by experiment and theory. [7,8] Ultrafast x-ray diffraction (UXRD) emerged as a powerful tool to observe lattice motion in real time [9][10][11] and has provided a deeper insight in the structure-property relations of functional oxides on ultrashort timescales. Recent femtosecond x-ray scattering experiments on ferroelectric oxides showed that electron screening induces an ultrafast piezoelectric response of the lattice [12] and that in turn the deformation leads to a change of the polarization.[13] However, these experiments were conducted on rather perfect epitaxial crystals. The influence of nano-domains has been considered in experiments on transient phases [14], but the role of static structural defects remained unexplored on such ultrafast timescale.Here we exemplify how ultrafast reciprocal space mapping (URSM) using a laser-based plasma x-ray source yields direct additional information on the reversible inplane structure dynamics in a ferroelectric perovskite PbZr 0.2 Ti 0.8 O 3 (PZT) film which is solely induced by the existence of dislocations typical of such materials. In particular, the width of the PZT Bragg reflection reports that tensile out of plane strain leads to drastically increased damping. The energy flows into in-plane strain which is evidenced by the in-plane component of the reciprocal space map. Our results indicate that in mismatched epitaxial films of oxide materials, with their high * daniel.schick@uni-potsdam.de • a-domains are embedded in the matrix of the c-axis grown tetragonal PZT film, as proved by the AFM topography image in b) as well. Misfit dislocations (MD) and threading dislocations (TD) formed at the SRO-PZT interface and across the PZT film, accounting for the lateral inhomogeneity on a sub-100 nm length scale.susceptibility to the formation of domains and dislocations, in-plane phenomena emerge on a hundred picosecond timescale. URSM yields the relevant information on lateral lattice dynamic...

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confidence: 99%

Following Strain-Induced Mosaicity Changes of Ferroelectric Thin Films by Ultrafast Reciprocal Space Mapping

et al. 2013

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“…We again chose the layer parameters according to Tables 1 and 2 and built a substrate composed of 5000 unit cells underneath. We assume an instantaneous heating and subsequent rapid expansion of the absorbing metal layers [24,25]. Since no anharmonic effects are included in the calculations the obtained results scale with the excitation fluence.…”

Section: Theorymentioning

confidence: 97%

Observing backfolded and unfolded acoustic phonons by broadband optical light scattering

2015

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“…3(b) suggest a delay between 200 and 700 fs, a more detailed analysis as a function of pump fluence has been presented in Ref. 83. A second stress component originates from magnetostriction, i.e., a change of the lattice dimensions of SRO upon reducing the magnetization by photoexcitation.…”

Section: A Real-space Atomic Motions and Vibrational Dynamicsmentioning

confidence: 99%

“…Femtosecond x-ray diffraction experiments have provided detailed insight into the dynamics of semiconductor 45 and perovskite SLs, [77][78][79][80][81][82][83][84][85] in the latter including ultrafast motions along different anharmonically coupled lattice coordinates. 79 Here, we present results for the ferromagnetic SRO/STO superlattice structure introduced in Fig.…”

Section: A Real-space Atomic Motions and Vibrational Dynamicsmentioning

confidence: 99%

Fitting coupled potential energy surfaces for large systems: Method and construction of a 3-state representation for phenol photodissociation in the full 33 internal degrees of freedom using multireference configuration interaction determined data

Zhu

Yarkony

2014

The Journal of Chemical Physics

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A recently reported algorithm for representing adiabatic states coupled by conical intersections using a quasi-diabatic state Hamiltonian in four and five atom systems is extended to treat nonadiabatic processes in considerably larger molecules. The method treats all internal degrees of freedom and uses electronic structure data from ab initio multireference configuration interaction wave functions with nuclear configuration selection based on quasi-classical surface hopping trajectories. The method is shown here to be able to treat ∼30 internal degrees of freedom including dissociative and large amplitude internal motion. Two procedures are introduced which are essential to the algorithm, a null space projector which removes basis functions from the fitting process until they are needed and a partial diagonalization technique which allows for automated, but accurate, treatment of the vicinity of extended seams of conical intersections of two or more states. These procedures are described in detail. The method is illustrated using the photodissociaton of phenol, C6H5OH(${\rm \tilde X}{}^{1} A^{\prime} $X̃1A′) + hv → C6H5OH($\tilde A{}^{1} A^{\prime} $Ã1A′, ${\rm \tilde B}{}^{\rm 1}{\rm A^{\prime \prime} }$B̃1A′′) → C6H5O(${\rm \tilde X}{}^2{\rm B}_1$X̃2B1, ${\rm \tilde A}{}^2{\rm B}_2$Ã2B2) + H as a test case. Ab initio electronic structure data for the 1,2,31A states of phenol, which are coupled by conical intersections, are obtained from multireference first order configuration interaction wave functions. The design of bases to simultaneously treat large amplitude motion and dissociation is described, as is the ability of the fitting procedure to smooth the irregularities in the electronic energies attributable to the orbital changes that are inherent to nonadiabatic processes.

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Comparing the oscillation phase in optical pump-probe spectra to ultrafast x-ray diffraction in the metal-dielectric SrRuO3/SrTiO3superlattice

Cited by 29 publications

References 39 publications

Following Strain-Induced Mosaicity Changes of Ferroelectric Thin Films by Ultrafast Reciprocal Space Mapping

Following Strain-Induced Mosaicity Changes of Ferroelectric Thin Films by Ultrafast Reciprocal Space Mapping

Observing backfolded and unfolded acoustic phonons by broadband optical light scattering

Fitting coupled potential energy surfaces for large systems: Method and construction of a 3-state representation for phenol photodissociation in the full 33 internal degrees of freedom using multireference configuration interaction determined data

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