Fluence dependent femtosecond quasi-particle and Eu^{2+} -spin   relaxation dynamics in EuFe_{2}(As,P)_{2}
  We investigated temperature and fluence dependent dynamics of the time resolved optical reflectivity in undoped spin-density-wave (SDW) and doped superconducting (SC) EuFe$_{2}$(As,P)$_{2}$ with emphasis on the ordered Eu$^{2+}$-spin temperature region. The data indicate that the SDW order coexists at low temperature with the SC and Eu$^{2+}$-ferromagnetic order. Increasing the excitation fluence leads to a thermal suppression of the Eu$^{2+}$-spin order due to the crystal-lattice heating while the SDW order is suppressed nonthermally at a higher fluence. 
A. Pogrebna (1), T. Mertelj (1,2), G. Cao (3), Z. A. Xu (3), D.   Mihailovic (1,2) ((1) Complex Matter Dept., Jozef Stefan I...
cond-mat.supr-con