My research encompasses the use of ultrashort (10^-15sec) nonlinear laser, x-ray and electron spectroscopies to probe various aspects of condensed matter systems. Key questions being addressed are the speed limits, as determined by the laws of physics, for the switching of magnetic and electronic states relevant for instance in information technology materials. Of particular interest is to observe, understand and ultimately control the emergence of novel non-equilibrium and possibly metastable states that have no equivalent in thermal equilibrium but are instrumental for determining the material’s function. The prime example is the observation of a transient ferromagnetic state occurring during all-optical magnetic switching of ferrimagnets. However, such metastable states may also be revealed during insulator-metal transitions in strongly correlated electron materials and are relevant for ultrafast charge separation in photovoltaics. The use of femtosecond soft x-ray pulses from free electron laser sources and EUV pulses from high-harmonic laser sources offers the advantage to simultaneously access ultra-small nanoscale dimensions and ultra-short timescales. Very recently I became interested in and am discovering the joys and pitfalls of using relativistic electron pulses for structural dynamics in a wide range of materials. I closely collaborate with external research groups and industry to gain access to materials relevant to information technology and other applications.
A list of my publications is available at
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