H.A. Dürr (Helmholtz Zentrum Berlin, BESSY)
Ultrafast charge, orbital and spin dynamics in complex materials
The interplay between electronic, spin and lattice degrees of freedom often determines the function of complex materials such as ferromagnets, high TC superconductors, colossal magnetoresistive and multiferroic oxides. Charge and orbital ordering phenomena can lead to metal-insulator transitions with temperature or chemical doping. These phenomena can ideally be studied using soft x-rays which probe directly the valence orbitals responsible for electronic and spin order. Time resolved optical pump – x-ray probe studies offer the exciting prospect of observing the flow of energy and angular momentum in real time. Here I will concentrate on ferromagnetic materials where x-ray dichroism is a unique probe of the spin order while x-ray resonant scattering provides direct access to orbital and charge order. Examples of ultrafast laser induced demagnetization of Gd and laser induced melting of charge order in magnetite will be described.