Head of Group

Photo of Prof. Dr. Bärbel Rethfeld

Prof. Dr. Bärbel Rethfeld

Building 46, Room 470

Phone: +49 631 205 2385
Fax: +49 631 205 3903

E-Mail: rethfeld[at]physik.uni-kl.de

Curriculum Vitae

Secretary

Photo of Anna Mihanovic

Anna Mihanovic

Building 46, Room 458

Phone: +49 631 205 2692
Fax: +49 631 205 3903

E-Mail: mihanovi[at]rhrk.uni-kl.de

Researchers

Photo of Nils Brouwer

M. Sc. Sanjay Ashok

Building 46, Room 472

Phone: +49 631 205 4717
Fax: +49 631 205 3903

E-Mail: ashok[at]physik.uni-kl.de

Photo of Johan Briones

M. Sc. Johan Briones

Building 46, Room 473

Phone: +49 631 205 4714
Fax: +49 631 205 3903

E-Mail: briones[at]rhrk.uni-kl.de

Photo of Nils Brouwer

Dipl.-Phys. Nils Brouwer

Building 46, Room 472

Phone: +49 631 205 4717
Fax: +49 631 205 3903

E-Mail: brouwer[at]physik.uni-kl.de

Photo of Isabel Klett

Dipl.-Phys. Isabel Klett

Building 46, Room 472

Phone: +49 631 205 4717
Fax: +49 631 205 3903

E-Mail: klett[at]physik.uni-kl.de

Foto von Pascal Diougue Ndione

M. Sc. Pascal Diougué Ndione

Building 46, Room 472

Phone: +49 631 205 4717
Fax: +49 631 205 3903

E-Mail: ndione[at]rhrk.uni-kl.de

Photo of Sebastian Weber

Dipl.-Phys. Sebastian Weber

Building 46, Room 474

Phone: +49 631 205 3973
Fax: +49 631 205 3903

E-Mail: weber[at]physik.uni-kl.de

Master Student

Photo of Andreas Hauch

B. Ed. Andreas Hauch

Building 46, Room 473

Phone: +49 631 205 4714
Fax: +49 631 205 3903

E-Mail: hauch[at]rhrk.uni-kl.de

Student Research Assistants

Photo of Kai Klein

Kai Klein

Building 46, Room 472

Phone: +49 631 205 4717
Fax: +49 631 205 3903

E-Mail: klein[at]physik.uni-kl.de

Alumni

Dr. Anika Rämer Foto von Anika Rämer

PhD Thesis: Excitation and Relaxation Dynamics in Laser-Excited Semiconductors and Dielectrics

Dipl.-Phys. Oliver Brenk Foto von Oliver Brenk
Dr. Klaus Huthmacher Photo of Klaus Huthmacher

Current Position: Financial Engineer at EDG AG in Frankfurt.

PhD Thesis: A Monte Carlo simulation of electron dynamics in laser-excited liquid water

Dr. Vladimir Lipp Photo of Vladimir Lipp

Current Position: Postdoc at the Center of Free Electron Laser science at DESY in Hamburg.

PhD Thesis: Atomistic-continuum modeling of ultrafast laser-induced melting of silicon targets

Dipl.-Phys. Linda Thesing Photo of Linda Thesing

Current Position: Graduate student at the Center for Free-Electron Laser Science (CFEL), Deutsches Elektronen-Synchrotron DESY

Diploma Thesis: Transport Effects and Ultrafast Magnetization Dynamics in Laser-excited Metals

Dr. Dimitry Ivanov Photo of Dr. Dimitry Ivanov

Current position: Researcher at the University of Kassel

M. Ed. Nicole Haupt Photo of Nicole Haupt

Master Thesis: Development and testing of a module for school laboratory on “magnetism” for third- and fourth-graders

Dr. Benedikt Müller Photo of Dr. Benedikt Müller

Current Position: Employee at KSB in Frankenthal

PhD Thesis: Relaxation dynamics of spin-resolved electron distributions in laser-excited metals

Description: Exciting a ferromagnetic material with an ultrashort laser pulse leads to a demagnetization of the sample in less than one picosecond. The reason for this ultrafast demagnetization process is investigated in this work. A kinetic model is derived, which describes the collisions between electrons and phonons, as well as spin-flip processes of electrons.

In the first part of this work, the electron dynamics after an ultrashort laser excitation of different materials is investigated by numerical simulations. The electrons, which are driven out of thermal equilibrium, thermalize with each other and transfer energy to the lattice. In particular, the influence of the nonequilibrium electrons on these processes is investigated.

In order to extend this model to ferromagnetic materials, the spin-flip processes are treated by a spin-resolved Boltzmann equation. The results are compared to the experimental results and the driving force of ultrafast demagnetization is identified: It is shown, that the change of magnetization is determined by the equilibration of the nonequilibrium of the temperatures and chemical potentials of majority and minority electrons. Moreover, a shift of electron energy states leads to an important feedback effect in ultrafast magnetization dynamics.

With the results of the spin-resolved Boltzmann equation, a macroscopic model is derived, which describes the spin dynamics in laser excited ferromagnets. Within this model, a magnetic phase diagram is presented, which describes the slowing down of magnetization dynamics for certain laser excitation strengths.

M. Ed. Katharina Eberhard Photo of Katharina Eberhard

Current Position: Teacher at Wilhelm-von-Humbold-Gymnasium Ludwigshafen

Master Thesis: Optics and magnetism for elementary school students - development and testing of student experiments

Dr. David Autrique Photo of Dr. David Autrique

PhD Thesis: Multiphase modelling of a ns-laser-irradiated copper sample

Dr. Orkhan Osmani Photo of Dr. Orkhan Osmani

PhD Thesis: Irradiation effects of swift heavy ions in matter

Description: The main research field is the Irradiation effects of swift heavy ions, i.e. ions with energies of more than 100 MeV and masses of more than 12 proton masses, in insulators and semiconductors. In particular, the creation of structural modifications of the target due to the swift heavy ion irradiation. Such swift heavy ions predominantly dissipate their energy by exciting the electronic system of the target which then heat the lattice system via electron-phonon interactions. The main focus of my studies are, the approach from a non-thermal to a thermal distribution as well as the transport properties of the excited electrons. Furthermore, statistical properties of swift heavy ions in matter, like charge exchange processes, the mean energy loss and the straggling are studied.

Dr. Nikita Medvedev Photo of Dr. Nikita Medvedev

Current Position: Scientist at Institute of Physics ASCR in Prague, Czech Republic.

PhD Thesis: Excitation and relaxation of the electronic subsystem in solids after high energy deposition

Description: Modeling of ultrafast material modifications after femto-second VUV-XUV irradiation with Monte-Carlo modeling, ab-initio Molecular Dynamics, Boltzmann transport equations, and a hybrid model of all of these approaches.

Patrick Heil Photo of Patrick Heil

Current position: Teacher at Bertha-von-Suttner IGS Kaiserslautern

Thesis: Entwicklung, Erprobung und Evaluation zweier Lehr-Lern-Einheiten zur Förderung des physikalischen Verständnisses in der Primarstufe

Guests

Dr. Dirk Gericke Foto von Dr. Dirk Gericke

October - December 2015

Current Position: Associate Professor (Reader) at Centre for Fusion, Space and Astrophysics, University of Warwick

Rory Baggott Foto von Rory Baggott

October - December 2015

Current Position: Ph. D. Student at Centre for Fusion, Space and Astrophysics, University of Warwick

Dr. Jeremy R. Gulley Photo of Dr. Jeremy Gulley

April - June 2012

Current Position: Assistant Professor of Physics at the Department of Biology & Physics, Kennesaw State University

PhD Thesis: Simulation of ultrashort pulse propagation and plasma generation in nonlinear media

Description: Dr. Gulley's research is centered on intense-ultrashort laser-pulse propagation through dielectrics. The physics of high-power laser-pulse propagation is strongly influenced by nonlinear optical effects. Of particular importance is the Kerr effect which, at high laser intensities, can change an ordinarily transparent material into an effective lens and significantly modify the pulse spectrum. Pulse propagation is further driven by the competing processes of diffraction, dispersion, ionization, and laser-plasma interactions. To predict this behavior it is necessary to simultaneously model both the pulse propagation as well as the material dynamics on the femtosecond time scale. Gulley's research focuses on developing new models of ultrashort pulse propagation, ultrafast laser-material interaction, and simulating these processes for experimentally-measured laser fields. In particular, he is developing new models to reconcile the equations governing ultrafast laser-material interactions with those of pulse-propagation to account for the multi-chromatic nature of ultrashort pulses.

Dr. Jan Vorberger Photo of Dr. Jan Vorberger

January - March 2012

Current Position: Researcher at Helmholtz Zentrum Dresden Rossendorf

PhD Thesis: Gleichgewichtseigenschaften dichter Plasmen

Description: Plasma physics with special interest in dense plasmas and warm dense matter. Equilibrium and nonequilibrium properties of these systems as they may be relevant for the basic understanding of matter under extreme conditions, for stars, giant gas planets, and (inertial) fusion devices.

In particular, I am interested in structural properties of warm dense matter in connection to modern x-ray scattering techniques. Furthermore, I'm working on theory of the equation of state and phase transition properties of, e.g., hydrogen, helium, or mixtures. In addition, I'm involved in work concerning temperature relaxation and energy transfer in two temperature plasmas.

Theoretical tools employed in these undertakings are the quantum statistical theory of Green's function (GF), classical statistical theory (HNC), Monte Carlo (MC) and molecular dynamics (MD), quantum simulation techniques such as density functional theory (DFT), and hybrid technologies like DFT-MD or GF-DFT.