TY  - JOUR
A1  - Mattern, M.
A1  - Pudell, Jan-Etienne
A1  - Laskin, G.
A1  - von Reppert, A.
A1  - Bargheer, Matias
T1  - Analysis of the temperature- and fluence-dependent magnetic stress in laser-excited SrRuO3
JF  - Structural Dynamics
N2  - We use ultrafast x-ray diffraction to investigate the effect of expansive phononic and contractive magnetic stress driving the picosecond strain response of a metallic perovskite SrRuO3 thin film upon femtosecond laser excitation. We exemplify how the anisotropic bulk equilibrium thermal expansion can be used to predict the response of the thin film to ultrafast deposition of energy. It is key to consider that the laterally homogeneous laser excitation changes the strain response compared to the near-equilibrium thermal expansion because the balanced in-plane stresses suppress the Poisson stress on the picosecond timescale. We find a very large negative Grüneisen constant describing the large contractive stress imposed by a small amount of energy in the spin system. The temperature and fluence dependence of the strain response for a double-pulse excitation scheme demonstrates the saturation of the magnetic stress in the high-fluence regime.
KW  - Thin films
KW  - Thermodynamic properties
KW  - Bragg peak
KW  - Ultrafast X-ray diffraction
KW  - Thermal effects
KW  - Phonons
KW  - Magnetism
KW  - Lattice dynamics
KW  - Lasers
KW  - Perovskites
Y1  - 2020
U6  - https://doi.org/10.1063/4.0000072
SN  - 2329-7778
ER  - 
TY  - JOUR
A1  - Zeuschner, Steffen
A1  - Parpiiev, Tymur
A1  - Pezeril, Thomas
A1  - Hillion, Arnaud
A1  - Dumesnil, Karine
A1  - Anane, Abdelmadjid
A1  - Pudell, Jan-Etienne
A1  - Willig, Lisa
A1  - Rössle, Matthias
A1  - Herzog, Marc
A1  - von Reppert, Alexander
A1  - Bargheer, Matias
T1  - Tracking picosecond strain pulses in heterostructures that exhibit giant magnetostriction
JF  - Structural Dynamics
N2  - We combine ultrafast X-ray diffraction (UXRD) and time-resolved Magneto-Optical Kerr Effect (MOKE) measurements to monitor the strain pulses in laser-excited TbFe2/Nb heterostructures. Spatial separation of the Nb detection layer from the laser excitation region allows for a background-free characterization of the laser-generated strain pulses. We clearly observe symmetric bipolar strain pulses if the excited TbFe2 surface terminates the sample and a decomposition of the strain wavepacket into an asymmetric bipolar and a unipolar pulse, if a SiO2 glass capping layer covers the excited TbFe2 layer. The inverse magnetostriction of the temporally separated unipolar strain pulses in this sample leads to a MOKE signal that linearly depends on the strain pulse amplitude measured through UXRD. Linear chain model simulations accurately predict the timing and shape of UXRD and MOKE signals that are caused by the strain reflections from multiple interfaces in the heterostructure.
KW  - Heterostructures
KW  - Magnetooptical effects
KW  - Metal oxides
KW  - Crystal lattices
KW  - Transition metals
KW  - Magnetism
KW  - Ultrafast X-ray diffraction
KW  - Lasers
KW  - Bragg peak
KW  - Phonons
Y1  - 2019
U6  - https://doi.org/10.1063/1.5084140
SN  - 2329-7778
VL  - 6
IS  - 2
PB  - AIP Publishing LLC
CY  - Melville, NY
ER  -