TY  - JOUR
A1  - Mattern, Maximilian
A1  - Pudell, Jan-Etienne
A1  - Dumesnil, Karine
A1  - von Reppert, Alexander
A1  - Bargheer, Matias
T1  - Towards shaping picosecond strain pulses via magnetostrictive transducers
JF  - Photoacoustics
N2  - Using time-resolved x-ray diffraction, we demonstrate the manipulation of the picosecond strain response of a metallic heterostructure consisting of a dysprosium (Dy) transducer and a niobium (Nb) detection layer by an external magnetic field. We utilize the first-order ferromagnetic–antiferromagnetic phase transition of the Dy layer, which provides an additional large contractive stress upon laser excitation compared to its zerofield response. This enhances the laser-induced contraction of the transducer and changes the shape of the picosecond strain pulses driven in Dy and detected within the buried Nb layer. Based on our experiment with rare-earth metals we discuss required properties for functional transducers, which may allow for novel field-control of the emitted picosecond strain pulses.
KW  - picosecond ultrasonics
KW  - magnetostriction
KW  - ultrafast x-ray diffraction
KW  - ultrafast photoacoustics
KW  - nanoscale heat transfer
KW  - negative thermal expansion
Y1  - 2023
U6  - https://doi.org/10.1016/j.pacs.2023.100463
SN  - 2213-5979
VL  - 30
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Koc, A.
A1  - Reinhardt, M.
A1  - von Reppert, Alexander
A1  - Rössle, Matthias
A1  - Leitenberger, Wolfram
A1  - Gleich, M.
A1  - Weinelt, M.
A1  - Zamponi, Flavio
A1  - Bargheer, Matias
T1  - Grueneisen-approach for the experimental determination of transient spin and phonon energies from ultrafast x-ray diffraction data: gadolinium
JF  - Journal of physics : Condensed matter
N2  - 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 simple Grueneisen approach, the strain is decomposed into two contributions proportional to the thermal energy of spin and phonon subsystems. Our analysis reveals that upon femtosecond laser excitation, phonons and spins can be driven out of thermal equilibrium for several nanoseconds.
KW  - ultrafast
KW  - x-ray diffraction
KW  - magnetostriction
KW  - nonequilibrium
KW  - spin
KW  - phonon
KW  - rare earth
Y1  - 2017
U6  - https://doi.org/10.1088/1361-648X/aa7187
SN  - 0953-8984
SN  - 1361-648X
VL  - 29
SP  - 5884
EP  - 5891
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -