Employing the momentum-sensitivity of time- and angle-resolved photoemission spectroscopy we demonstrate the analysis of ultrafast single- and many-particle dynamics in antiferromagnetic EuFe_{2}As_{2}. Their separation is based on a temperature-dependent difference of photo-excited hole and electron relaxation times probing the single particle band and the antiferromagnetic gap, respectively. Reformation of the antiferromagnetic state occurs at 800 fs, which is four times slower compared to electron-phonon equilibration due to a smaller spin-dependent relaxation phase space.
The original publication is available by link DOI:
10.1103/PhysRevLett.108.097002