Publications (42)
Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy
M. Beck, M. Klammer, S. Lang +4
Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor Nb…
Photoinduced absorption from localized intra-gap states
V. V. Kabanov, J. Demsar, D. Mihailovic
A model is developed for photoinduced absorption from localized states observed in femtosecond pump-probe experiments in high-Tc superconductors and other materials. The dynamics o…
Robust hybridization gap in a Kondo Insulator YbB probed by femtosecond optical spectroscopy
A. R. Pokharel, S. Y. Agustsson, V. V. Kabanov +4
In heavy fermions the relaxation dynamics of photoexcited carriers has been found to be governed by the low energy indirect gap, E, resulting from hybridization between local…
Time-Resolved Optical Studies of Quasiparticle Dynamics in High-Temperature Superconductors: Experiments and theory
D. Mihailovic, J. Demsar
Ultrafast time-resolved optical spectroscopy in high-temperature superconductors enables the direct real-time measurement of non-equilibrium quasiparticle recombination dynamics. I…
Non-thermal separation of electronic and structural orders in a persisting charge density wave
M. Porer, U. Leierseder, J. -M. Ménard +7
The simultaneous ordering of different degrees of freedom in complex materials undergoing spontaneous symmetry-breaking transitions often involves intricate couplings that have rem…
Quasiparticle relaxation dynamics in heavy fermion compounds
J. Demsar, R. D. Averitt, K. H. Ahn +5
We present the first femtosecond studies of electron-phonon (e-ph) thermalization in heavy fermion compounds. The e-ph thermalization time tau_{ep} increases below the Kondo temper…
Single particle and collective excitations in the one-dimensional charge density wave solid K0.3MoO3 probed in real time by femtosecond spectroscopy
J. Demsar, K. Biljakovic, D. Mihailovic
Ultrafast transient reflectivity changes caused by collective and single particle excitations in the quasi one-dimensional charge-density wave (CDW) semiconductor K0.3MoO3 are inve…
Ultrafast Polaron Dynamics in Layered and Perovskite Manganites: 2D and 3D Polarons
J. Lee, H. J. Lee, R. D. Averitt +8
We have studied the sub-picosecond quasiparticle dynamics in the perovskite manganite La0.7Ca0.3MnO3 and the layered manganite La1.4Sr1.6Mn2O7 using ultrafast optical spectroscopy.…
Ultrafast transient generation of spin-densitywave order in the normal state of BaFe2As2 driven by coherent lattice vibrations
K. W. Kim, A. Pashkin, H. Schäfer +7
The interplay among charge, spin and lattice degrees of freedom in solids gives rise to intriguing macroscopic quantum phenomena such as colossal magnetoresistance, multiferroicity…
Distinct charge and spin gaps in underdoped YBa2Cu3O7-x
D. Mihailovic, V. V. Kabanov, K. Zagar +1
A systamatic quantitative comparison of ''pseudogap'' values obtained from the analysis of charge and spin excitation spectroscopies in underdoped YBa2Cu3O7-x using a temperature-i…
Carrier relaxation dynamics in heavy fermion compounds
J. Demsar, L. A. Tracy, R. D. Averitt +3
The first femtosecond carrier relaxation dynamics studies in heavy fermion compounds are presented. The carrier relaxation time shows a dramatic hundred-fold increase below the Kon…
Carrier relaxation dynamics in intra-gap states: the case of the superconductor Y Ba_2 Cu_3O_7-delta and the charge-density-wave semiconductor K_0.3MoO_3
V. V. Kabanov, J. Demsar, D. Mihailovic
The unusual slow carrier relaxation dynamics - observed in femtosecond pump-probe experiments on high-temperature superconductors and recently also in a charge-density-wave system…
Kinetics of a superconductor excited with a femtosecond optical pulse
V. V. Kabanov, J. Demsar, D. Mihailovic
Superconducting state dynamics following excitation of a superconductor with a femtosecond optical pulse is studied in terms of a phenomenological Rothwarf and Taylor model. Analyt…
Quasiparticle relaxation dynamics in cuprates and lifetimes of low-energy states: Femtosecond data from underdoped to overdoped YBCO and mercury compounds
D. Mihailovic, J. Demsar, R. Hudej +3
We show that low-energy spectral features in the cuprates can be separated into different components by the measurement of the recombination dynamics of different low-energy excita…
Quasiparticle relaxation dynamics in superconductors with different gap structures: theory and experiments on YBa_{2}Cu_{3}O_{7-δ}
V. V. Kabanov, J. Demsar, B. Podobnik +1
Photoexcited quasiparticle relaxation dynamics are investigated in a superconductor as a function of doping and temperature using ultrafast time-re…
Femtosecond quasiparticle relaxation dynamics and probe polarization anisotropy in YBa2Cu4O8
D. Dvorsek, V. V. Kabanov, J. Demsar +2
Femtosecond pump probe experiments are reported on quasiparticle relaxation and recombination in YBa2Cu4O8 as a function of temperature and polarization. The data show a 2-componen…
Optical control of vibrational coherence triggered by an ultrafast phase transition
M. J. Neugebauer, T. Huber, M. Savoini +13
Femtosecond time-resolved x-ray diffraction is employed to study the dynamics of the periodic lattice distortion (PLD) associated with the charge-density-wave (CDW) in K0.3MoO3. Us…
Ultrafast real-time spectroscopy of low dimensional charge density wave compounds
J. Demsar, D. Mihailovic, V. V. Kabanov +1
We present a femtosecond time-resolved optical spectroscopy (TRS) as an experimental tool to probe the changes in the low energy electronic density of states as a result of short a…
Ultrafast quasiparticle relaxation dynamics in normal metals and heavy fermion materials
K. H. Ahn, M. J. Graf, S. A. Trugman +4
We present a detailed theoretical study of the ultrafast quasiparticle relaxation dynamics observed in normal metals and heavy fermion materials with femtosecond time-resolved opti…
Photoinduced melting of superconductivity in the high-Tc superconductor La2-xSrxCuO4 probed by time-resolved optical and THz techniques
M. Beyer, M. Beck, D. Städter +6
Dynamics of depletion and recovery of superconducting state in La2-xSrxCuO_4 thin films is investigated utilizing optical pump-probe and optical pump - THz probe techniques as a fu…
Dynamics of photoinduced Charge Density Wave-metal phase transition in K0.3MoO3
A. Tomeljak, H. Schäfer, D. Städter +3
We present first systematic studies of the photoinduced phase transition from the ground charge density wave (CDW) state to the normal metallic (M) state in the prototype quasi-1D…
Femtosecond Quasiparticle and Phonon Dynamics in Superconducting YBa2Cu3O7 Studied by Wideband Terahertz Spectroscopy
A. Pashkin, M. Porer, M. Beyer +10
We measure the anisotropic mid-infrared response of electrons and phonons in bulk YBa2Cu3O7 after femtosecond photoexcitation. A line shape analysis of specific lattice modes revea…
Evidence for crossover from a Bose-Einstein condensate to a BCS-like superconductor with doping in YBa2Cu3O(7-x) from quasiparticle relaxation dynamics experiments
J. Demsar, B. Podobnik, J. Evetts +2
Time resolved measurements of quasiparticle (QP) relaxation dynamics on the femtosecond timescale are reported as a function of temperature and doping in YBa2Cu3O(7-x) for (0.48 <…
Hot electron relaxation in a heavy fermion system with tuned doping
J. Demsar, V. V. Kabanov, A. S. Alexandrov +4
Femtosecond time-resolved optical spectroscopy was used to systematically study photoexcited carrier relaxation dynamics in the intermediate-valence heavy fermion system Yb1-xLuxAl…
Morphology Effectively Controls Singlet-Triplet Exciton Relaxation and Charge Transport in Organic Semiconductors
V. K. Thorsmølle, R. D. Averitt, J. Demsar +7
We present a comparative study of ultrafast photo-conversion dynamics in tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical pump-probe spectroscopy. Photo…
Divergence of the quasiparticle lifetime with doping and evidence for pre-formed pairs below T* in YBa_2Cu3$O_{7-δ}
D. Mihailovic, B. Podobnik, J. Demsar +2
We report new time-resolved data of quasiparticle relaxation and Cooper pair recombination dynamics in YBa_2Cu_3O_{7-δ}, measured as a function of temperature and doping δusing f…
Chirality in the Kagome Metal CsVSb
H. J. Elmers, O. Tkach, Y. Lytvynenko +22
Using x-ray photoelectron diffraction (XPD) and angle-resolved photoemission spectroscopy, we study photoemission intensity changes related to changes in the geometric and electron…
Control of the asymmetric band structure in Mn2Au by a ferromagnetic driver layer
Y. Lytvynenko, O. Fedchenko, S. V. Chernov +15
Hard X-ray angle-resolved photoemission spectroscopy reveals the momentum-resolved band structure in an epitaxial Mn2Au(001) film capped by a 2 nm thick ferromagnetic Permalloy lay…
Femtosecond data storage, processing and search using collective excitations of a macroscopic quantum state
D. Mihailovic, D. Dvorsek, V. V. Kabanov +3
An ultrafast paralell data processor is described in which amplitude mode excitations of a charge density wave (CDW) are used to encode data on the surface of a 1-T TaS_2 crystal.…
Orbital magnetization in the Nb-substituted Kagome metal CsVSb
H. J. Elmers, O. Tkach, Y. Lytvynenko +12
This study uses angle-resolved photoemission spectroscopy to examine the low-temperature electronic structure of Cs(VNb)Sb, demonstrating that partially s…
The superconducting gap Î_{c}, the pseudogap Î_{p} and pair fluctuations above Tc in overdoped YCaBaCuO from femtosecond time-domain spectroscopy
J. Demsar, B. Podobnik, V. V. Kabanov +2
The low-energy electronic excitation spectrum and gap structure in optimally doped and overdoped Y_{1-x}Ca_{x}Ba_{2}Cu_{3}O_{7-δ} single crystals are investigated by real-time mea…
A study of photoexcited carrier relaxation in YBa_2Cu_3O_(7-d) by picosecond resonant Raman spectroscopy
T. Mertelj, J. Demsar, B. Podobnik +2
The temperature dependence of the energy relaxation of photoexcited (PE) carriers is used as a probe of the electronic structure of YBa_2Cu_3O_(7-d) in the insulating d~0.8 and met…
Ultrafast dynamics of charge density waves in 4Hb-TaSe2 probed by femtosecond electron diffraction
N. Erasmus, M. Eichberger, K. Haupt +6
The dynamics of the photoinduced commensurate to incommensurate charge density wave (CDW) phase transition in 4Hb-TaSe2 are investigated by femtosecond electron diffraction. In the…
Quasiparticle dynamics and gap structure in Hg1223 investigated with femtosecond spectroscopy
J. Demsar, R. Hudej, J. Karpinski +2
Measurements of the temperature dependence of the quasiparticle (QP) dynamics in Hg1223 with femtosecond time-resolved optical spectroscopy are reported. From the temperature depen…
Néel Spin Orbit Torque driven antiferromagnetic resonance in MnAu probed by time-domain THz spectroscopy
N. Bhattacharjee, A. A. Sapozhnik, S. Yu. Bodnar +11
We observe the excitation of collective modes in the THz range driven by the recently discovered Néel spin-orbit torques (NSOT) in the metallic antiferromagnet MnAu. Tempera…
Femtosecond "snapshots "of gap-forming charge-density-wave correlations in quasi-two-dimensional dichalcogenides 1T-TaS2 and 2H-TaSe2
J. Demsar, L. Forro, H. Berger +1
Time-resolved optical spectroscopy of collective and single-particle excitations of 1T-TaS2 and 2H-TaSe2 reveals the presence of a large gap in the excitation spectrum on the femto…
Melting the Superconducting State in the Electron Doped Cuprate PrCeCuO with Intense near-infrared and Terahertz Pulses
M. Beck, M. Klammer, I. Rousseau +8
We studied the superconducting (SC) state depletion process in an electron doped cuprate PrCeCuO by pumping with near-infrared (NIR) and narrow-band THz…
Quasiparticle relaxation dynamics in Hg-1223 studied by femtosecond time-resolved optical spectroscopy
J. Demsar, R. Hudej, J. Karpinski +2
Following recent progress in understanding the relaxation dynamics of photoexcited carriers in materials exhibiting a small gap in the low-energy excitation spectrum we have perfor…
Pair-breaking and superconducting state recovery dynamics in MgB2
J. Demsar, R. D. Averitt, A. J. Taylor +5
We present studies of the photoexcited quasiparticle dynamics in MgB2 where, using femtosecond optical techniques, Cooper pair breaking dynamics (PBD) have been temporally resolved…
Low-energy electronic structure in Y1-xCaxBa2Cu3O7-y comparison of t ime-resolved optical spectroscopy, NMR, neutron and tunneling data
J. Demsar, K. Zagar, V. V. Kabanov +1
Time-resolved optical measurements give information on the quasiparticle relaxation dynamics in YBCO, from which the evolution of the gap with doping and temperature can be systema…
Controlled vaporization of the superconducting condensate in cuprate superconductors sheds light on the pairing boson
P. Kusar, V. V. Kabanov, S. Sugai +3
We use ultrashort intense laser pulses to study superconducting state vaporization dynamics in La(2-x)Sr(x)CuO4 (x=0.1 and 0.15) on the femtosecond timescale. We find that the ener…
Disentanglement of the electronic and lattice parts of the order parameter in a 1D Charge Density Wave system probed by femtosecond spectroscopy
H. Schäfer, V. V. Kabanov, M. Beyer +2
We report on the high resolution studies of the temperature (T) dependence of the q=0 phonon spectrum in the quasi one-dimensional charge density wave (CDW) compound K0.3MoO3 utili…