Bärbel Rethfeld

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The extreme cooling rates in material processing can be achieved in a number of current and emerging femtosecond laser techniques capable of highly localized energy deposition. The mechanisms of rapid solidification of a nanoscale region of a metal film transiently melted by a localized photoexcitation are investigated in a large-scale atomistic simulation.(More)
Motivated by the recent controversy about the importance of spin-flip scattering for ultrafast demagnetization in ferromagnets, we study the spin-dependent electron dynamics based on a dynamical Elliott-Yafet mechanism. The key improvement to earlier approaches is the use of a modified Stoner model with a dynamic exchange splitting between majority and(More)
Laser ablation in an ambient gas is nowadays used in a growing number of applications, such as chemical analysis and pulsed laser deposition. Despite the many applications, the technique is still poorly understood. Therefore models describing the material evolution in time during short pulse laser irradiation can be helpful to unravel the puzzle and finally(More)
Ultrafast dynamical processes in solids may be triggered, studied and even manipulated with help of ultrashort laser pulses. Also for materials processing there is an enormous potential of ultrashort laser pulses. Thus, femtosecond laser–solid interaction is of significant interest to the fields of both basic research and industrial applications. Here, I(More)
Ion tracks formed in amorphous Ge by swift heavy-ion irradiation have been identified with experiment and modeling to yield unambiguous evidence of tracks in an amorphous semiconductor. Their underdense core and overdense shell result from quenched-in radially outward material flow. Following a solid-to-liquid phase transformation, the volume contraction(More)
The present study focuses on the role of mass removal mechanisms in ns-laser ablation. A copper sample is placed in argon, initially set at standard pressure and temperature. Calculations are performed for a 6 ns laser pulse with a wavelength of 532 nm and laser fluences up to 10 J/cm 2. The transient behavior in and above the copper target is described by(More)
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