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We study the propagation of a density wave in a magnetically trapped Bose-Einstein condensate at finite temperatures. The thermal cloud is in the hydrodynamic regime and the system is therefore described by the two-fluid model. A…

Quantum Gases · Physics 2015-05-14 R. Meppelink , S. B. Koller , P. van der Straten

The dynamics of thermal and non-thermal lattice deformation of nanometer thick polycrystalline aluminum film has been studied by means of femtosecond (fs) time-resolved electron diffraction. We utilized two different pump wavelengths: 800…

Materials Science · Physics 2017-09-13 Runze Li , Pengfei Zhu , Jie Chen , Jianming Cao , Peter M. Rentzepis , Jie Zhang

This letter calculates the contribution of electron-phonon interaction to thermoelectric effects in graphene. One considers the case of free standing graphene taking into account interaction with intrinsic acoustic phonons. The temperatures…

Mesoscale and Nanoscale Physics · Physics 2015-08-18 S. V. Koniakhin , E. D. Eidelman

Femtosecond core-level transient absorption spectroscopy is utilized to investigate photoinduced dynamics of the charge density wave in 1T-TiSe2 at the Ti M2,3 edge (30-50 eV). Photoexcited carriers and phonons are found to primarily induce…

Materials Science · Physics 2022-11-08 Tobias Heinrich , Hung-Tzu Chang , Sergey Zayko , Kai Rossnagel , Murat Sivis , Claus Ropers

We study gadolinium thin films as a model system for ferromagnets with negative thermal expansion. Ultrashort laser pulses heat up the electronic subsystem and we follow the transient strain via ultrafast X-ray diffraction. In terms of a…

Strongly Correlated Electrons · Physics 2017-06-28 A. Koc , M. Reinhardt , A. von Reppert , M. Roessle , W. Leitenberger , M. Gleich , M. Weinelt , F. Zamponi , M. Bargheer

The transient acoustic response of a free-standing, polycrystalline thin Au film upon femtosecond optical excitation has been studied by time-resolved Debye-Scherrer X-ray diffraction using ultrashort Cu K$_{\alpha}$ X-ray pulses from a…

Mesoscale and Nanoscale Physics · Physics 2019-12-11 W. Lu , M. Nicoul , U. Shymanovich , F. Brinks , M. Afshari , A. Tarasevitch , D. von der Linde , K. Sokolowski-Tinten

We theoretically analyze the Bragg spectroscopic interferometer of two spatially separated atomic Bose-Einstein condensates that was experimentally realized by Saba et al. [Science 2005 v307 p1945] by continuously monitoring the relative…

Quantum Gases · Physics 2012-08-03 M. D. Lee , S. Rist , J. Ruostekoski

Semiconductor materials are the foundation of modern electronics, and their functionality is dictated by the interactions between fundamental excitations occurring on (sub-)picosecond timescales. Using time-resolved Raman spectroscopy and…

In Peierls-distorted materials, photoexcitation leads to a strongly coupled transient response between structural and electronic degrees of freedom, always measured independently of each other. Here we use transient reflectivity in the…

We compute the transient dynamics of phonons in contact with high energy "hot" charge carriers in 12 polar and non-polar semiconductors, using a first-principles Boltzmann transport framework. For most materials, we find that the decay in…

Mesoscale and Nanoscale Physics · Physics 2017-10-03 Sridhar Sadasivam , Maria K. Y. Chan , Pierre Darancet

We performed the experimental and theoretical study of the heating and damaging of ruthenium thin films induced by femtosecond laser irradiation. Results of an optical pump-probe thermoreflectance experiment with rotating sample allowing to…

We investigate the transient photoexcited lattice dynamics in a layered perovskite Mott insulator Sr2IrO4 by femtosecond X-ray diffraction using a laser plasma-based X-ray source. Ultrafast structural dynamics of Sr2IrO4 thin films are…

Atomic and Molecular Clusters · Physics 2017-04-26 Bing-Bing Zhang , Jian Liu , Xu Wei , Da-Rui Sun , Quan-Jie Jia , Yuelin Li , Ye Tao

The first order standard perturbation theory combined with ab initio projector augmented wave operator challenges the realization of the standard Sternheimer equation with linear computational efficiency. This efficiency motivates us to…

Materials Science · Physics 2018-10-05 Sushant Kumar Behera , Pritam Deb

We present a first-principles method for the calculation of the temperature-dependent relaxation of symmetry-breaking atomic driving forces in photoexcited systems. We calculate the phonon-assisted decay of the photoexcited force on the…

The femtosecond evolution of the electronic temperature of laser-excited gold nanoparticles is measured, by means of ultrafast time-resolved photoemission spectroscopy induced by extreme-ultraviolet radiation pulses. The temperature of the…

This review discusses picosecond ultrasonics experiments using ultrashort hard x-ray probe pulses to extract the transient strain response of laser-excited nanoscopic structures from Bragg-peak shifts. This method provides direct,…

We propose an embedding of standard active particle models in terms of two-temperature processes. One temperature refers to an ambient thermal bath, and the other temperature effectively describes ``hot spots,'' i.e., systems with few…

Statistical Mechanics · Physics 2024-01-23 Faezeh Khodabandehlou , Christian Maes

We perform ultrafast pump-probe measurements on a nanometer-thick crystalline Bi-doped yttrium iron garnet film with perpendicular magnetic anisotropy. Tuning the photon energy of the pump laser pulses above and below the material's…

Mesoscale and Nanoscale Physics · Physics 2021-08-18 Lucile Soumah , Davide Bossini , Abdelmadjid Anane , Stefano Bonetti

We have shown that it is possible to model accurately optical phenomena in intense laser fields by taking into account the intensity distribution over the laser beam. We developed a theoretical model that divided an intense laser beam into…

Atomic Physics · Physics 2016-03-09 Marcis Auzinsh , Andris Berzins , Ruvin Ferber , Florian Gahbauer , Uldis Kalnins

Building on a recently improved understanding of the problem of heat flow in general relativity, we develop a hydrodynamical model for coupled finite temperature superfluids. The formalism is designed with the dynamics of the outer core of…

General Relativity and Quantum Cosmology · Physics 2015-06-12 N. Andersson , C. Krueger , G. L. Comer , L. Samuelsson